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Prospective Evaluation of Zirconia Posterior Fixed Partial Dentures: 7-Year Clinical Results
Abstract
PURPOSE:
The clinical performance of three- and four-unit fixed partial dentures (FPDs) with frameworks made of yttria partially stabilized zirconia was determined after a mean observational period of 84 months.
MATERIALS AND METHODS:
Seventy-five patients were treated with 99 posterior FPDs. Fifty-one specimens were veneered with an experimental ceramic suitable for titanium and zirconia frameworks; 48 restorations were veneered with a commercially available low-fusing ceramic optimized for zirconia frameworks. All restorations were luted with zinc-phosphate cement. Statistical analysis was performed according to Kaplan-Meier; potential risk factors were analyzed using the Cox regression analysis.
RESULTS:
Nineteen restorations failed completely: 12 due to technical complications, 6 due to biologic complications, and 1 for unknown reasons. The overall survival rate after 84 months was 83.4%. Thirty-two events required clinical intervention for restoration maintenance, resulting in a time-dependent success rate of 57.9% after 84 months. Nineteen dropouts occurred during the follow-up time. None of the evaluated factors showed an association with survival or success of the restorations.
CONCLUSIONS:
After a mean observational period of 7 years, the survival and success rates of zirconia-based posterior FPDs were inferior to those published for metal-ceramic FPDs. The majority of failures were caused by technical complications (material fractures). The main reasons for clinical intervention to maintain function were fractures of the veneering ceramic and decementations.
... Pelaez et al. [14] suggested a 100% survival rate for PFM in the posterior region, and Hey et al. [18] suggested an 88% survival rate for PFM in the anterior and posterior regions. Researchers [19][20][21][22][24][25][26][27][28] proposed an 88-95% survival rate for the all-ceramic posterior region, while Sola-Ruiz et al. [23] proposed an 89% survival rate for the all-ceramic anterior region. ...
... The duration of this review was selected from January 2012 because, at the same time, Anusavice [6] gave standardised criteria for the success, survival, and failure of any FPD prosthesis. From Table 1, it is clear that the most commonly seen failure in PFM tooth-supported prostheses was veneer chipping [16][17][18][19][21][22][23][24][25][26], which led to the exposure of the metallic substructure. Catastrophic fractures occur very rarely. ...
... The most frequently occurring biological failures were periodontal pocket formation and gingival swelling [25][26]28]. Secondary caries was seen in a few cases as well [17,19,21,25]. The survival of PFM prosthesis was seen to be the lowest (88%) when it was studied in patients with bruxism as a para-functional habit. ...
The prosthesis must have good survival despite being functional for at least 5-10 years. This makes sure that the replacement of missing teeth does not become a repeated expense. Of 579 identified articles, 15 met the inclusion criteria for systematic review. Missing teeth replacement materials are divided into two groups: porcelain fused to metal and all ceramics. Data related to survival rates as well as the most common mode of
failure is observed from both groups. It was observed that porcelain fused to metal prostheses had an approximately 99.5% survival rate and an approximately 92% survival rate for all-ceramic tooth-supported prostheses after five years of insertion. Porcelain-fused-to-metal (PFM) prostheses had a better survival rate after five years of insertion as compared to all-ceramic prostheses. Porcelain fused to metal should be the treatment of choice for dentists and patients when missing teeth need to be fixed.
... For multiple restorations, 29 studies evaluated two-retainer FPDs [16, 44, 47, 49, 52-55, 59, 62, 63, 65, 66, 71-78, 80, 82, 84, 85, 87, 89, 92, 93]. Of these, 8 studies did not report on the connector dimensions [47,52,54,55,63,73,75,76]. The other 21 studies reported connectors with areas between 6 and 16 mm 2 [16,44,49,53,59,62,65,66,71,72,74,77,78,80,82,84,85,87,89,92,93]. Three studies evaluated cantilevered FPDs [56,61,81], one did not report the dimensions of the connector [81] and the other two studies used connectors with areas ranging from 5 to 12 mm 2 [56,61]. ...
... Regarding the treatment of the internal surface of the zirconia for cementation, 13 studies performed sandblasting with aluminum oxide, followed or not by cleaning with alcohol or ultrasonic bath [50,55,56,62,66,70,71,78,81,82,84,90,94], one study performed sandblasting with aluminum oxide followed by silane application [58], three studies performed sandblasting with CoJet (silicatization) [51,59,87], four studies only reported cleaning of the surface with alcohol [49,52,63,88], one study reported that no surface treatment was performed [85], and 30 studies did not report this information [16, 44-48, 53, 54, 57, 60, 61, 64, 65, 67-69, 72-77, 79, 80, 83, 86, 89, 91-93]. Fifteen studies reported cementation of the restorations with resin cement [49-52, 54-56, 58, 66, 71, 81, 82, 85, 87, 92], 11 with selfadhesive resin cement [44,48,59,61,65,67,75,76,80,86,88], and one used both conventional and self-adhesive resin cement [69]. ...
... Fifteen studies reported cementation of the restorations with resin cement [49-52, 54-56, 58, 66, 71, 81, 82, 85, 87, 92], 11 with selfadhesive resin cement [44,48,59,61,65,67,75,76,80,86,88], and one used both conventional and self-adhesive resin cement [69]. Thirteen studies used conventional glass ionomer cement to lute the restorations [16, 45, 46, 57, 60, 62-64, 72, 83, 84, 89, 94], six used resin-modified glass ionomer cement [47,53,70,77,79,90], two used zinc phosphate cement [78,93], two used zinc phosphate and resin cement [74,91], and two studies did not report the luting agent used [68,73]. ...
Objectives
This systematic review was performed to determine the main cause of technical failure of tooth-supported zirconia crowns and fixed partial dentures (FPDs), categorizing them as fracture/chipping or loss of retention/decementation.
Materials and methods
Electronic and manual searches were performed for randomized clinical trials, prospective clinical trials, and prospective cohort studies that reported the technical failure rates of zirconia restorations. The Cochrane Collaboration risk-of-bias tool and Newcastle–Ottawa scale were used to assess the quality of the studies.
Results
Fifty-two studies were included and most of them had unclear risk of bias. Considering all reported fractures/chipping, for veneered crowns with 1 to 3 years of follow-up, the relative risk (RR) of fracture in relation to loss or retention was 3.95 (95% CI 1.18–13.23; p = 0.03). For 4 to 6 years of follow-up, the RR was 5.44 (95% CI 1.41–20.92; p = 0.01). For veneered FPDs with 1 to 3 years of follow-up, the RR was 5.98 (95% CI 2.31–15.01; p = 0.0002). For 4 to 6 years of follow-up, the RR was 3.70 (95% CI 1.63–8.41; p = 0.002). For 7 years or more of follow-up, the RR was 3.45 (95% CI 1.84–6.46; p = 0.0001). When only framework fractures were considered, there were no significant differences for the RR in all follow-up periods (p > 0.05).
Conclusions
Higher RR for fracture/chipping in relation to decementation for veneered zirconia crowns and FPDs at all follow-up times. For framework fractures, no difference was observed between the risk of failure of the restoration due to fracture or decementation.
Clinical relevance
Zirconia crowns and FPDs showed relatively high success and survival rates. However, considering the technical failures, there is approximately four times higher chance of fracture/chipping than loss of retention for both single and multi-unit tooth-supported veneered zirconia restorations.
... The majority of the studies (6) were prospective (42.9%) [39,40,42,44,48,50], followed by 5 randomized controlled clinical trials (35.7%) [37,38,[45][46][47] and, lastly, 3 studies (21.4%) with a retrospective longitudinal design [41,43,49] (Figure 3). The majority of the studies for all-ceramic FPDs had a prospective and retrospective design, and one was a randomized clinical control trial (RCT). ...
... Most of the studies evaluated densely sintered zirconia (49%), followed by metalceramic (25%), reinforced glass-ceramic (21%), and glass-infiltrated alumina (5%) (Figure 4). The systems that were used and evaluated in the included studies were: Procera (Nobel Biocare, Gothenburg, Sweden), Cercon (Dentsply Friadent, Mannheim, Germany), Lava (Pre-Sintered) (3M ESPE, Seefeld, Germany), DC-Zircon (HIP) [41], CAM systems, manually fabricated frameworks making mock-ups and FPDs produced by milling Cercon brain (DeguDent, Hanau, Germany) sintered densely for 6 h at 1350 • C [42], presintered Cercon Zirconia, Everest, Lava (3M ESPE, Seefeld, Germany), IPS e.max ZirCAD, Wol-Ceram (Alumina) (Wol-Dent, Bad Soberheim, Germany), IPS e.max ZirPress (Ivoclar Vivadent Ellwangen, Germany) [37], Denzir HIPed Y-TZP (Detronic AB skellefteå) [43], Cercon-Ceram (Dentsply Friadent, Mannheim, Germany [45], abutments digitized with InEos scanner (Dentsply Sirona, York, PA, USA), VITA VM 13 (VITA Zahnfabrik, Bad Säckingen, Germany) [47], Lava Ultimate (3M, Seefeld, Germany) [48], and IPS e.max lithium disilicate CAD-CAM (Ivoclar Vivadent Ellwangen, Germany) [49]. Metal-ceramic restorations were fabricated in laboratories cooperating with the universities or private practices by means of the lost-wax technique or simple wax mock-ups with base-metal and high-noble framework materials. ...
... In this respect, Sulaiman et al. observed a low failure rate for lithium disilicate FPDs in a follow-up period of up to 7.5 years, which is in accordance with our results [57]. Koenig et al. [41] reported that the occurrence of framework fracture was always localized at the junction between the connector and the pontic FPD and depended on the following parameters: the number of elements, the nature of antagonists, and the type of support, which showed high significance apart from these complications. To sum up, most of the reported technical complications were chipping, with a few cases of replacement. ...
The metal-ceramic fixed partial prosthesis is the golden standard for posterior tooth restorations. Following the demands of patients and clinicians for metal-free restorations, all-ceramic materials were developed as they offer an adequate alternative with better optical qualities and good mechanical properties. This study aims to carry out a bibliographic review to assess the survival rate and the biological and technical complications of all-ceramic and metal-ceramic fixed partial dentures. An electronic search for articles in the English language literature was performed using PubMed (MEDLINE). This literature review focused on research studies between 2010 and 2020 that performed clinical studies on tooth-supported fixed partial dentures with a mean follow-up of at least 3 years. All the studies, which analyzed the survival and complications of tooth-supported fixed partial dentures, were included. Thus, 14 studies reporting on 756 all-ceramic and 160 metal-ceramic fixed partial dentures met the inclusion criteria. A comparative analysis was carried out based on all the data existing in the studies included in this review. The metal-ceramic fixed partial dentures showed survival rates of 95% to 100% at 3-, 5-, and 10-year follow-up periods. Zirconia fixed partial dentures were reported to have survival rates of 81% to 100% at 3-, 5-, 9-, 10-year follow-up evaluations. The reinforced glass-ceramic fixed partial dentures showed survival rates of 70% to 93.35% at 5 years, while the alumina FPDs showed a survival rate of 68% at 3 years follow-up. The incidence of caries and loss of vitality were reported as higher for all-ceramic prostheses as compared to the metal-ceramic ones. A significant framework fracture was reported for glass-infiltrated alumina fixed partial dentures in comparison to metal-ceramic fixed partial dentures. All-ceramic and metal-ceramic restorations showed similar survival rates after 3 years, although all-ceramic restorations have problems with technical complications such as chipping, which can lead to framework fractures over time.
... Also, for coloring ceramics, the method of adding metal oxides to the original ceramic powder can be used. According to published clinical studies, the destruction rate of the zirconium dioxide scaffolds is low, ranging from 0 % to 4.8 % [16][17][18][19][20]. Moreover, fractures were reported in only two out of six studies [16,21]. ...
... Nevertheless, despite high scaffold survival rates, zirconium dioxide-based reconstructions often occur in the presence of biological or technical problems [16][17][18][19][20][21]. The most common technical problem is the chipping or fracture of veneering ceramics [16][17][18][19][20][21]. ...
... Nevertheless, despite high scaffold survival rates, zirconium dioxide-based reconstructions often occur in the presence of biological or technical problems [16][17][18][19][20][21]. The most common technical problem is the chipping or fracture of veneering ceramics [16][17][18][19][20][21]. This technical difficulty has been reported in most studies with a frequency of 8 % to 25 % [16,19,20]. ...
This descriptive review presents current knowledge about the bioengineering use of a zirconium dioxide, the advantages and disadvantages of the material, and the prospects for research in this direction. The work reflects the success of the practical application of the zirconium dioxide as a material for dental structures and biological implants. Such practical characteristics, such as color-stability, chemical stability, good aesthetics, biocompatibility and durability, allowed to actively use the zirconium dioxide as a material for producing various dental structures. In comparison with other ceramics, the presence of high-performance of strength and fracture toughness of the zirconium dioxide enables the use of this material as an alternative material for the reconstructions in the readings with considerable loads. High hardness determines the zirconium dioxide as an excellent material for articular prostheses, because of its hardness, provides a low level of wear and excellent biocompatibility. However, along with positive characteristics, a widespread practical problem of using the zirconium dioxide in dentistry is a chip or fracture of veneering ceramics. It has also been reported that there is a shortage of orthopedic implants such as hydrothermal stability. The solution of such problems is indicated and the use of composite materials based on the zirconium dioxide, which allows to solve a similar problem, as well as to increase the service life and reliability of orthopedic implants by providing a higher fracture toughness and mechanical strength. The existence of such composite materials based on the zirconium dioxide provides a significant increase in the wear resistance of orthopedic implants, which is essential for successful prosthetics
... Rinke et al [12] studied the clinical outcomes of posterior CAM-fabricated zirconia FDPs after a mean observational period of 7 years and reported survival probability of 83% and success probability (no clinical intervention needed to maintain the restoration in situ) of 57.9 %. They claimed the survival and success rates of zirconia FDPs were decreased with increasing observational periods (94% for 4 years and 83% for 7 years [12,13]. ...
... Rinke et al [12] studied the clinical outcomes of posterior CAM-fabricated zirconia FDPs after a mean observational period of 7 years and reported survival probability of 83% and success probability (no clinical intervention needed to maintain the restoration in situ) of 57.9 %. They claimed the survival and success rates of zirconia FDPs were decreased with increasing observational periods (94% for 4 years and 83% for 7 years [12,13]. and the technical failures as the majority of total failures. ...
... The patient's general satisfaction in both groups was high (9.1±0.7 for metal ceramic and Rinke et al [12] showed the increasing annual failure rate of zirconia tooth-supported FDPs from 1.5% within 1-4 years to 3.3% within 5-7 years. They found that the success rate of these restorations after 7 years (57.9%) are inferior to metal ceramic FDPs after 10 years (89.2%) ...
Objectives
The implant-supported restorations can be made of all-ceramic materials. The purpose of this study was to compare five year clinical outcomes of zirconia-based and metal ceramic implant-supported fixed dental prostheses (FDPs)
Methods
In this study, 114 posterior implant-supported FDPs including zirconia-based (52) or metal ceramic (62) restorations were made for 114 patients with a mean age of 59 ± 8.4 year and evaluated in a 5 year follow up. The modified California Dental
Association (CDA) guidelines were used to assess the quality of the restorations. The soft tissue status was evaluated using gingival and plaque indices, probing depth and bleeding on probing. Additionally, the bone loss around implants was assessed by parallel priapical radiographs. The visual analogue scale was used regarding patients’ satisfaction. The data analysis were performed by Kaplan-Meier, log ranked test, cox regression, Mann-Whitney U and student’s t-test. (α = 0.05)
Results
Five year Kaplan-Meier survival rate of the zirconia-based and metal ceramic FDPs were 98.1% and 100% respectively with no significant difference (P = 0.12). The success rates were 81.6% for zirconia-based and 81.0% for metal ceramic restorations (P = 0.85). The CDA rating of both studied groups was not significantly different except the marginal gap which was better in zirconia-based FDPs (P < 0.001). Fracture of veneering ceramics occurred in 2.7% of metal ceramic and 6.4% of zirconia-based FDPs, which were not considered as failure. Soft tissue status was not affected by the type of restorations except for plaque index which was more favorable for zirconia-based FDPs (P < 0.001). No significant difference was found between marginal bone loss of the two groups (P = 0.30 mesial, P = 0.46 distal).
Conclusions
Zirconia-based and metal ceramic FDPs showed similar promising clinical performance in the 5-year follow-up.
Clinical significance
Zirconia-based implant-supported FDPs might be a successful restorative method with acceptable survival rate and patient's satisfaction.
... In line with Rinke et al., the authors considered that the high marginal precision offered by the latest generations of CAD-CAM technologies allows clinicians to perform better [22]; therefore, deep chamfer margin preparation was chosen because it is simpler than a 90° shoulder or juxta-gingival chamfer, is more aesthetic and gives restoration a correct geometry that reduces occlusal stress [23][24][25][26]. ...
... In line with Rinke et al., the authors considered that the high marginal precision offered by the latest generations of CAD-CAM technologies allows clinicians to perform better [22]; therefore, deep chamfer margin preparation was chosen because it is simpler than a 90 • shoulder or juxta-gingival chamfer, is more aesthetic and gives restoration a correct geometry that reduces occlusal stress [23][24][25][26]. ...
The conventional metal–ceramic is still considered the gold standard in fixed prosthetics especially in terms of longevity. Among alternative materials used, Monolithic Zirconia has shown the capability to reconcile excellent biomechanical properties with acceptable aesthetic performance and to overcome several inconveniences related to veneer restorations. This study aims to clinically evaluate Monolithic Zirconia prosthetic crowns on natural abutments in the posterior sectors, performed by final-year dental medicine students (undoubtedly with less experience in the management of such material) by the standardized California Dental Association score system evaluation, to better understand the viability of Monolithic Zirconia. This prospective study was carried out at the Dental School of the University of Bari “Aldo Moro”, Italy. Prosthetic rehabilitation included single crowns or a short pontic prosthesis with maximum one intermediate. Final-year dental students performed tooth reduction under the supervision of three expert tutors. The California Dental Association systematics (based on color, surface, anatomical shape, and marginal integrity) were adopted to evaluate the prosthetic maintenance status over time. Annual follow-up visits were re-evaluated by the same parameters each year. Univariate logistic regression analysis was performed to evaluate outcomes and the Kaplan–Meier plot to report survival. The sample consists of 40 crowns performed on 31 patients, 15 males (48.4%) and 16 females (51.6%) with an average age of 59.3 years. The clinical cases subjected to experimental study were found to be “Excellent” (1a/2a/3a/4a) in 34 cases (85%), “Acceptable” in 4 cases (10%), and “To be re-done” in 2 cases (failures) (5%). Our conclusive data support the predictability of Monolithic Zirconia restorations on natural posterior abutments at a long-term follow-up of five years, even when performed by less-experienced clinicians.
... Despite zirconia being a tough material, there have been occasional functional fractures, with chipping in about 6.25% of cases [4]. In some cases, when the fracture of zirconia is exposed to the zirconia framework [4], emergency repairs can be made with zirconia primer, adhesive agent, and resin composite [5,6]. ...
... Despite zirconia being a tough material, there have been occasional functional fractures, with chipping in about 6.25% of cases [4]. In some cases, when the fracture of zirconia is exposed to the zirconia framework [4], emergency repairs can be made with zirconia primer, adhesive agent, and resin composite [5,6]. A surface treatment protocol should be performed before the repair with resin composite. ...
Occasional chipping can still occur with zirconia material despite its high strength. Emergency repairs can be accomplished using zirconia primer, adhesive agent, and resin composite when the fracture of zirconia exposes the zirconia framework. Phosphate-containing primers play an important role in zirconia surface treatment. The objective of this investigation was to evaluate the effect of multiple applications of phosphate-containing primer on shear bond strength between zirconia and resin composite. In this case, 78 zirconia discs were sandblasted by alumina particles; the zirconia was then randomized into six groups for single application and multiple applications of phosphate-containing primer according follows; group 1: no application, group 2: one application, group 3: two applications, group 4: three applications, group 5: four applications, and group 6: five applications. Adhesive was applied on the zirconia surface and the resin composite was bonded. Shear bond strength was assessed using a universal testing machine. The de-bonded surface was examined using a stereomicroscope. The shear bond strengths were statistically analyzed with one-way ANOVA and Bonferroni. Group 1 had the lowest shear bond strength with a significant difference compared to groups 2–6, whereas group 4 had the highest shear bond strength, with no significant difference compared to groups 5–6. The failure mode revealed 100% adhesive failure in all groups. In conclusion, to maximize shear bond strength at zirconia and resin composite interfaces, sandblasted zirconia surfaces should be treated with three applications of phosphate-containing primer prior to the adhesive agent.
... 18 The adhesive cementation should be performed whenever possible, as it generates higher bond and fatigue strength than conventional luting, which is related to a higher failure rate by retention loss. 11,19,20 Resin cements have better mechanical and optical properties, and higher resistance to abrasion and to hydrolysis, 21 despite their higher technical sensitivity and lower moisture tolerance. The introduction of functional monomers has improved the resin cement bond strength to zirconia, 13 but the effect of using different methacryloyloxy-decyl-dihydrogenphosphate (MDP)-containing cement systems in the fatigue behavior of cemented monolithic zirconia is still unclear. ...
... Longterm clinical data on monolithic zirconia treatments are still scarce 5 ; however, clinical studies with zirconiabased restorations have shown that fracture and retention loss are their main reasons for failure. [6][7][8][9][10][11] When considering the factor "retention loss" for all-ceramic restorations, one of the aggravating characteristics is their internal relief. Unlike metalceramics, which have a certain primary friction to the dental substrate when cemented, all-ceramic crowns are not able to withstand such tension without damage. ...
This study investigated the fatigue failure load of simplified monolithic yttria partially stabilized zirconia polycrystal restorations cemented to a dentin-like substrate using different luting systems. Disc-shaped ceramic (Zenostar T, 10 mm Ø × 0.7 mm thick) and dentin-like substrate (10 mm Ø × 2.8 mm thick) were produced and randomly allocated into eight groups, without or with thermocycling (TC=5–55°C/12,000×): “cement” (RelyX Luting 2 – glass ionomer cement [Ion], [Ion/TC]; RelyX U200 – self-adhesive resin cement [Self], [Self/TC]; Single Bond Universal+RelyX Ultimate – MDP-containing adhesive + resin cement [MDPAD + RC], [MDP-AD + RC/TC]; ED Primer II+Panavia F 2.0 – Primer + MDP-containing resin cement [PR + MDP-RC], [PR + MDP-RC/TC])). Each luting system was used as recommended by the manufacturer. Staircase methodology (20 Hz; 250,000 cycles) was applied for obtaining the fatigue failure loads. Fractographic characteristics were also assessed. At baseline, the Ion group presented the lowest fatigue load, although it was statistically similar to the Self group. The resin-based cement systems presented the highest fatigue performance, with the Ion group being only statistically equal to the Self group. Thermocycling influenced the groups differently. After aging, the MDP-AD + RC presented the highest mean, followed by the PR + MDP-RC and Self groups, while the Ion group had the lowest mean. Fractographic analysis depicted all failures as radial cracks starting at the zirconia intaglio surface. The luting system with MDP-containing adhesive applied prior to the resin cement presented the highest fatigue failure load after aging, presenting the best predictability of stable performance. Despite this, monolithic zirconia presents high load-bearing capability regardless of the luting agent.
... It has been demonstrated that chipping mostly occurred in premolars and molars, in connectors of mandibular posterior FDPs, and in second molars of FDPs. 25,33,34 In addition, it has been reported that chipping occurred in nonload-bearing sites, such as the lingual side of FDPs [25][26][27][28][29][30][31][32][33][34][35] and the mesiolingual cusps of mandibular second molars. [25][26][27][28][29][30][31][32][33][34][35][36] In the present investigation, zirconia FDPs recorded relatively high mean failure load values (842. ...
... 25,33,34 In addition, it has been reported that chipping occurred in nonload-bearing sites, such as the lingual side of FDPs [25][26][27][28][29][30][31][32][33][34][35] and the mesiolingual cusps of mandibular second molars. [25][26][27][28][29][30][31][32][33][34][35][36] In the present investigation, zirconia FDPs recorded relatively high mean failure load values (842. .375 ...
Objective The purpose of this study was to evaluate the influence of the connector area on the chipping rate of the VM9 veneering ceramic in a 4-unit yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) framework, using a novel sonographic technique.
Materials and Methods The framework was designed as a 4-unit fixed dental prostheses (FDP) with two abutment teeth at the first mandibular premolar and second mandibular molar. The cross-sectional area of the connector was 7.5, 8, or 9 mm2. The prepared teeth were scanned using CAD/CAM technology, and five frameworks were prepared for each design, making a total of 15. The frameworks were divided according to the veneering ceramics: Y-TZP FDPs using Vita VM9 (12 frameworks), and porcelain fused to metal (PFM) FDPs using Vita VM13 (3 frameworks). The specimens were statically loaded until failure. To capture the initiation of the failure within the specimens, a novel sonographic technique, designed for this research, combining acoustic emission and visual monitoring during live load bearing tests, was used to determine the failure load value. Failed frameworks were inspected using a microscope, and failure patterns were identified. One-way ANOVA and Tukey HSD tests were applied for statistical analysis of the results (p-value ≤ 0.05).
Results Despite the fact that the chipping strength is proportional to the cross-sectional area of the connector, the effect of the cross-sectional area on chipping load revealed no statistically significant differences, while PFMs showed superior chipping strength relative to the zirconia frameworks regardless of the connector's size. A high rate of catastrophic fracture occurred while loading the specimens.
Conclusion The effect of the cross-sectional area on chipping load revealed no statistically significant differences in Y-TZP frameworks. The novel sonographic technique may be a potential method to study the behavior of dental ceramics, including chipping and fracture.
... The second common reason for failure was chipping. Eight publications showed either chipping or cracks of the ceramic, requiring replacement of the restoration [31,38,44,50]. This accounts for 10/52 (19.2%) of all observed failure cases. ...
... Loss of retention as another type of complication leading to either failure or repair without replacement of the FDP was addressed by six studies [30][31][32]35,44,50] and occurred in 22/603 (3.65%) of all cases, not considering drop-outs. Five of these studies reported the cementation material and used adhesive [41,44] or conventional [30,32,40] methods. ...
Although CAD/CAM ceramics present a promising alternative to metal-ceramic fixed dental prostheses, little is known about their mid- and long-term clinical performance. This systematic review aims to estimate the survival and success rates and describes the underlying complication characteristics for CAD/CAM tooth-supported zirconia- and lithium disilicate-based fixed dental prostheses (FDPs). We systematically searched MEDLINE and Web of Science to find relevant prospective studies with a follow-up of at least one year. We estimated pooled 1-, 5-, and 10-year survival and success rates by combining the collected data in a Poisson regression model. Descriptive statistics were conducted to evaluate the distribution of failures and complications in the included studies. Risk of bias for the included studies was assessed with an adapted checklist for single-arm trials. Pooled estimated 1-, 5-, and 10-year survival rates ranged from 93.80% to 94.66%, 89.67% to 91.1%, and 79.33% to 82.20%, respectively. The corresponding success rates excluding failures, but including any other types of intervention were 94.53% to 96.77%, 90.89% to 94.62%, and 81.78% to 89.25%. Secondary caries was the most frequent cause of failure, followed by chipping of the veneering. The most common cause of complication excluding failures but requiring intervention was chipping of the veneering. Risk of bias was generally acceptable for the included studies, with seven studies associated with low risk of bias, eight studies with a moderate risk of bias, and three studies with serious risk of bias. The current meta-analysis on CAD/CAM-supported FDPs revealed satisfying survival and success rates for up to 10 years of exposure. More prospective studies focusing on long-term performance are needed to strengthen the evidence currently available in the literature.
... The second common reason for failure was chipping. Eight publications showed either chipping or cracks of the ceramic, requiring replacement of the restoration [37,47,49,51,58]. This accounts for 10/52 (19.2%) of all observed failure cases. ...
... Loss of retention as another type of complication leading to either failure or repair without replacement of the FDP was addressed by six studies [49,51,52,58,62,65] and occurred in 22/603 (3.65%) of all cases not considering drop-outs. Five of these studies reported the cementation material and used adhesive [40,49] or conventional [29,39,65] methods. ...
Although CAD/CAM ceramics present a promising alternative to metal-ceramic fixed dental prostheses, little is known about their mid- and long-term clinical performance. This system- atic review aims to estimate the survival and success rates and describes the underlying complica- tion characteristics for CAD/CAM tooth-supported fixed dental prostheses (FDPs). We systemati- cally searched MEDLINE and Web of Science to find relevant prospective studies with a follow-up of at least one year. We estimated pooled 1-, 5- and 10-year survival and success rates by combining the collected data in a Poisson regression model. Descriptive statistics were conducted to evaluate the distribution of failures and complications in the included studies. Risk of bias for the included studies was assessed with an adapted checklist for single-arm trials. Pooled estimated 1-, 5-, and 10- year survival rates ranged from 93.80% to 94.66%, 89.67% to 91.1%, and 79.33% to 82.20%, respec- tively. The corresponding success rates, excluding failures but including any other types of inter- vention, were 94.53% to 96.77%, 90.89% to 94.62%, and 81.78% to 89.25%. Secondary caries was the most frequent cause of failure, followed by chipping of the veneering. The most common cause of complication, excluding failures but requiring intervention, was chipping of the veneering. Risk of bias was generally acceptable for the included studies, with 7 studies associated with low risk of bias, 8 studies with a moderate risk of bias, and 3 studies with serious risk of bias. The current meta- analysis on CAD/CAM supported FDPs revealed satisfying survival and success rates for up to 10 years of exposure. More prospective studies focusing on long-term performance are needed to strengthen the evidence currently available in the literature.
... These studies were performed on the buccal surface (side) of the prosthesis where chipping is most commonly observed ( de Lima et al., 2015 ;Rinke et al., 2013 ;Roediger et al., 2010 ) where the radius of curvature is at least an order of magnitude greater than the thickness of the coping. Therefore, the spherical/cylindrical form can be well approximated by that of an equibiaxially stressed plate at this position ( Young et al., 2002 ). ...
... It should be highlighted that the modelling outlined below is based on approximating the YPSZ-porcelain coping as an equibiaxially stressed plate, as previously exploited to great success in existing models within the literature ( Allahkarami et al., 2010 ;Ni et al., 2013 ;Olevsky et al., 2013 ;Swain et al., 2019 ). This approximation exploits the fact that the radius of curvature of the coping is at least an order of magnitude higher than its thickness on the buccal and lingual surfaces (sides) of the prosthesis, where porcelain chipping is primarily observed ( de Lima et al., 2015 ;Rinke et al, 2013 ;Roediger et al., 2010 ). By making use of this approach, the stress variation within the plane can be written as a function of a single positional descriptor ( x). ...
The exceptional strength and appealing aesthetics of porcelain veneered yttria partially stabilised zirconia (YPSZ) dental prostheses, has led to the widespread adoption of these materials. However, near-interface chipping of the porcelain remains the primary failure mode. Advanced experimental techniques have recently revealed significant variations in residual stress and YPSZ phase distribution at the YPSZ–porcelain interface. Therefore, in order to improve existing understanding and effectively optimise the production of these devices, an enhanced model of the YPSZ coping that includes these newly discovered phenomena is presented in this study.
Macroscale stresses are shown to arise through the uneven temperatures within the coping during the sintering process and the coefficient of thermal expansion mismatch with the porcelain during veneering. In contrast, microscale stresses are driven by the YPSZ phase transformation and the associated volumetric expansion. The eigenstrain approach proposed here was found to demonstrate a good match between the phase variation determined experimentally, and the corresponding residual stress distribution showed an effective comparison with the empirical measurements. The proposed technique is a straightforward but powerful method for simulating this dominant mechanical behaviour, with significant potential to combine the resulting expressions into existing models. These enhanced simulations are the only viable approach for the precise, reliable and systematic optimisation of prosthesis production parameters that are needed to significantly reduce prosthesis failure rates.
... Initial reports on zirconia restorations indicated a higher incidence of loss of retention, reaching up to 14% (1,31,67). Laboratory examinations of early generations of computer aided manufacturing (CAM) systems revealed that zirconia restorations exhibited suboptimal internal fit and marginal accuracy compared to PFM restorations (68)(69)(70). This discrepancy resulted in thicker cement layers (71), which compromise clinical longevity as they are prone to stress development, increasing the risk of rupture within the cement layer. ...
In recent decades, progress has been made in preventive dentistry. However, a significant part of the population still needs dental restorations. Dental ceramics, especially zirconia, are increasingly used as restorative materials. The advantages of using a metal-free restorative material are primarily due to their aesthetics and biocompatibility. Clinical reports on zirconia restorations indicate reliable results and that patients are generally satisfied with them. Nevertheless, they are not entirely free from complications, with loss of retention being a commonly reported problem. This issue may be attributed to the cement systems used to retain zirconia to the tooth, which can be technique sensitive.
This doctoral thesis comprises four studies with the overall aim of evaluating factors that can affect the adhesion between zirconia and the tooth surface, thereby enhancing the longevity of zirconia-based restorations. Study I was a laboratory study where the surface structure and bond strength of an adhesive cement to different types of zirconia were evaluated after various surface pretreatments. The mechanical method, alumina particle air abrasion, resulted in a rougher surface and increased bond strength between zirconia and cement compared to other surface pretreatments, regardless of the type of zirconia. In Study II, a systematic review and meta-analysis were conducted to analyse how the type of cement affects the survival of tooth-supported single crowns made of zirconia in posterior dentitions. The meta-analysis demonstrated excellent survival rates for these restorations over a three-year period. Few complications occurred, and there was no significant difference between the various types of cement, such as resin cement, glass ionomer cement, and resinmodified glass ionomer cement. Study III is a three-year follow-up of a randomized clinical trial where general practitioners performed three types of all-ceramic posterior tooth-supported single crowns. The results showed comparable survival rates between lithium disilicate glass ceramic and zirconia crowns. Additionally, there were few complications, and both patients and dentists were satisfied with the crowns. Study IV was an experimental laboratory investigation where products from two different adhesive cement systems were combined to evaluate their effect on the bond strength between zirconia and the tooth surface. The results indicated that combined products from different systems influenced bond strength both positively and negatively. To achieve optimal results, it is crucial to use products from the same cement system and follow the manufacturer’s instructions. In summary, achieving durable adhesion to zirconia involves using an MDPbased cement in combination with an air-abraded zirconia surface. Clinically, zirconia posterior tooth-supported single crowns exhibit excellent survival rates in the short-term, regardless of whether the cement system is resin, glass ionomer, or resin-modified glass ionomer cement.
... Buna göre yazarlar geleneksel siman kullanımının yeniden değerlendirilmesini tavsiye etmişlerdir. 33,34 Tek kron restorasyonlarda diş preparasyonunda ortalama 26 dereceden fazla preparasyon açısı önerilmiştir. 35 Bu nedenle, günlük uygulamada gerekli preparasyon uygulamalarının mümkün olup olmadığı tartışmalıdır ve geçmiş deneyimlere göre adeziv simantasyon daha yararlı görünmektedir. ...
Tam seramik restorasyonlar yıllardır diş hekimleri tarafından güvenle tercih edilen restorasyon çeşitlerindendir. Ancak hastaların seans sayısı ve süresinin kısalması ile birlikte artan estetik beklentisi, diş hekimliğinde dijital teknoloji kullanımının önemini artırmıştır. Güncel klinik uygulamalarda dijital diş hekimliğinin kullanımıyla birlikte, monolitik tam seramik restorasyonlara yönelim her geçen gün hızlanmaktadır. Bu talebe karşılık, üretici firmalar da içeriği ve özellikleri geliştirilmiş yeni materyalleri dental markete sunmaktadır. Özellikle yüksek estetik ve aynı zamanda mekanik dayanıklılığa sahip materyaller geliştirilmeye devam etmektedir. Zirkonya restorasyonlar yıllardır yüksek kırılma dayanım ve biyouyumluluk özellikleri nedeniyle tercih edilse de porselen-zirkonya bağlantısının zayıf olması (potansiyel chipping riski) ve nispeten düşük estetik (translusensi ve ışık geçirgenliği) özellikleri nedeniyle geliştirilmeye en açık restorasyon materyallerindendir. Zirkonyanın bu dezavantajlarını ortadan kaldırmak ve avantajlarından faydalanabilmek amacıyla üreticiler, zirkonyanın içyapısında değişiklikler yaparak monolitik kullanıma uygun hale getirmişlerdir. Ancak güncel kullanımda çok çeşitli monolitik zirkonya blokların bulunması, klinisyenin uygun materyal seçiminde zorluklar oluşturmaktadır. Bu derlemenin amacı klinisyenlere rehber olacak şekilde güncel monolitik zirkonya materyalinin sınıflandırmasını yapmaktır.
... Unfortunately, this is not the case with other complications, such as framework fractures, which mostly require prosthesis replacement. Some studies have reported that an increase in FDP length increases the risk of framework fractures [35,50]. ...
Backgrounds
Long-span dental bridges may cause excessive load on abutment teeth and the periodontal area, which may lead to bridge fractures or periodontal problems. However, some reports have revealed that short- and long-span bridges can provide a similar prognosis. This clinical study aimed to investigate the technical complications associated with fixed dental prostheses (FDPs) of different span lengths.
Methods
All patients with previously cemented FDPs were clinically examined during their follow-up visits. Several data related to FDPs were registered, such as design, material type, location, and type of complication. The main clinical factors analyzed were technical complications. Life table survival analyses were performed to calculate the cumulative survival rate of FDPs when technical complications were detected.
Results
The study examined 229 patients with a total number of 258 prostheses and an average of 98 months of follow-up. Seventy-four prostheses suffered from technical complications, and the most common complication was ceramic fracture or chipping (n = 66), while loss of retention occurred in 11 prostheses. The long-term evaluation of long-span prostheses revealed a significantly higher technical complication rate compared to short-span prostheses (P = ,003). The cumulative survival rate for short-span FDPs was 91% in year 5, 68% in year 10, and 34% in year 15. For long-span FDPs, the cumulative survival rate was 85% in year 5, 50% in year 10, and 18% in year 15.
Conclusion
Long-span prostheses (5 units or more) can be associated with a higher technical complication rate compared to short-span prostheses after long-term evaluation.
... The incidence of pulp necrosis was 3.27% when the compound material was used, but lower when reversible hydrocolloid material was used (1.19%). Thirteen studies used a single type of elastomeric impression material (polyether or polyvinyl siloxane) [21,23,26,27,32,33,36,38,44,47,48,51,52]. The incidence of pulp necrosis was higher when the impression was taken using polyether (4.02%) than where polyvinyl siloxane was used (3.17%). ...
Background
Restoring vital teeth with indirect restorations may threaten dental pulp integrity. However, the incidence of and influential factors on pulp necrosis and periapical pathosis in such teeth are still unknown. Therefore, this systematic review and meta-analysis aimed to investigate the incidence of and influential factors on pulp necrosis and periapical pathosis of vital teeth following indirect restorations.
Methods
The search was conducted in five databases, using MEDLINE via PubMed, Web of Science, EMBASE, CINAHL, and Cochrane Library. Eligible clinical trials and cohort studies were included. The risk of bias was assessed using Joanna Briggs Institute’s critical appraisal tool and Newcastle–Ottawa Scale. The overall incidences of pulp necrosis and periapical pathosis following indirect restorations were calculated using a random effects model. Subgroup meta-analyses were also performed to determine the potential influencing factors for pulp necrosis and periapical pathosis. The certainty of the evidence was assessed using the GRADE tool.
Results
A total of 5,814 studies were identified, of which 37 were included in the meta-analysis. The overall incidences of pulp necrosis and periapical pathosis following indirect restorations were determined to be 5.02% and 3.63%, respectively. All studies were assessed as having a moderate-low risk of bias. The incidence of pulp necrosis following indirect restorations increased when the pulp status was objectively assessed (thermal/electrical testing). The presence of pre-operative caries or restorations, treatment of anterior teeth, temporization for more than two weeks, and cementation with eugenol-free temporary cement, all increased this incidence. Final impression with polyether and permanent cementation with glass ionomer cement both increased the incidence of pulp necrosis. Longer follow-up periods (> 10 years) and treatment provided by undergraduate students or general practitioners were also factors that increased this incidence. On the other hand, the incidence of periapical pathosis increased when teeth were restored with fixed partial dentures, the bone level was < 35%, and the follow-up was > 10 years. The certainty of the evidence overall was assessed as low.
Conclusions
Although the incidences of pulp necrosis and periapical pathosis following indirect restorations remain low, many factors affect these incidences that should thus be considered when planning indirect restorations on vital teeth.
Database registration
PROSPERO (CRD42020218378).
... Although HIP nano zirconia exhibited lower strength than conventional 3 mole% zirconia, its strength is equivalent to conventional 4 mole% zirconia, which is suggested as an option for the fabrication of up to 3-unit posterior fixed bridges [36][37][38][39][40][41][42][43]. Despite this mechanical equivalence, there is little rationale for its use unless it could exhibit significantly better aesthetics monolithically or superior bond strength. ...
To investigate the flexural strength of hot isostatically pressed nano 3 mol% yttria partially stabilised zirconia and conventionally sintered micro 3 mole% yttria partially stabilised zirconia. Methods: A total of 40 bar-shaped (2 mm × 4 mm × 16 mm) specimens were prepared from hot isostatically pressed nano 3 mol% yttria partially stabilised zirconia (CeramaZirc Nano HIP, Precision Ceramics) and conventionally sintered micro 3 mole% yttria partially stabilised zirconia (CeramaZirc, Precision Ceramics). Two groups were prepared for each material (n = 10), with one serving as ‘control’ and the other being cyclically loaded using a chewing simulator (7 kg; 250 k cycles): SEM imaging was also undertaken on selected specimens. Flexural strength until fracture was recorded (ISO 6872). Paired and unpaired t-tests were chosen to compare mean outcomes between the four groups (p < 0.05). Results: Significant statistical difference was only found between the means of control specimens. CeramaZirc Nano HIP had the highest mean value (1048.9 MPa), whilst the lowest was seen for CeramaZirc after loading (770 MPa). Values for both materials were higher without loading than after loading. Values after cyclical loading showed large SD values (276.2–331.8) in comparison to ‘control’ (66.5–100.3). SEM imaging after cyclical loading revealed a smoother and less destructed surface of CeramaZirc Nano HIP compared to CeramaZirc. Significance: HIP nano zirconia exhibited inferior strength, surface polishability and behaviour to loading. Therefore, further investigation on the behaviour of such materials should be conducted before recommending for clinical use.
... In vitro studies have shown lower resistance when YSZs are cemented under non-adhesive strategies (Anami et al., 2016;Campos et al., 2017;Fraga et al., 2018). This fact corroborated by the significant retention loss rate of restorations of this material in the clinic when conventional zinc-phosphate cement was used (Rinke et al., 2013). ...
This study aims to characterize the effect of shading techniques on the fatigue behavior of a 4YSZ ceramic (4 mol% yttrium stabilized zirconia) adhesively bonded to a dentin analogue (fiber-reinforced epoxy resin). 4YSZ ceramic discs (IPS e.max ZirCAD, Ø = 10mm and 1 mm of thickness) were allocated according to the factor ‘shading technique’ into 4 groups: Brush– unshaded ceramic disc (IPS e.max ZirCAD BL) pigmented at the pre-sintered stage with pigment solution applied manually using a round liner brush; Immersion– unshaded ceramic disc pigmented through immersion in the solution for 1 second on only one side of the ceramic disc; Manufacturer– specimens already shaded by the manufacturer (IPS e.max ZirCAD MT A2 – Manufacturer group); Control– a control condition with absence of pigment (i.e. non-pigmented specimens). The specimens were sintered and a spectrophotometer (SP60, EX- Rite) was used to ensure that the same perceived color (i.e. pigment saturation) was achieved in the different shading strategies (Manufacturer, Brush or Immersion groups). To do so, the color differences (ΔE00) were calculated using the CIEDE 2000 equation; and an ΔE00 of up to 1.77 was considered as an acceptability threshold. Dentin analogue discs were obtained (Ø = 10 mm and 2.5 mm of thickness) and randomly allocated into pairs with the 4YSZ ceramic discs. Next, the pairs were adhesively bonded using a resin cement (Multilink N). The bonded assemblies (n = 15) were tested for fatigue using the step-stress test method (frequency of 20 Hz; 10,000 cycles per step, initial load 200 N; step-size of 100 N, up to 700 N; and after, step-size of 50 N, until specimen failure/fracture or radial cracks). Fatigue failure load (FFL) and number of cycles for failure (CFF) were recorded for statistical analysis. Fractographic features were accessed, and complementary roughness, topography, grain size and phase content analyses were performed. No statistical differences were observed in the fatigue behavior among the non-shaded condition (Control group – 880 N) and the shaded specimens (Manufacturer – 887 N, Brush – 820 N, and Immersion – 850 N groups; p > 0.05). However, the use of a brush shading technique induced slightly inferior fatigue mechanical behavior of the restorative set compared to the specimens already shaded by the manufacturer (p = 0.027). No differences in Weibull modulus were observed among the tested groups. The specimens pigmented by the brush technique demonstrated a rougher surface, with statistically higher Rz values, in addition to a larger grain size in comparison to all other conditions (p< 0.05). No m-phase content was identified (only t and c phases were detected). Thus, the shading techniques used to provide a Vita classic A2 shade does not negatively affect the mechanical fatigue properties of a bonded 4YSZ ceramic. However, the brush technique has detrimental effect on the fatigue behavior compared to when the ceramic was already provided in a shaded format by its manufacturer.
... These concerns were addressed by veneering the outer surface of the zirconia framework with feldspar-based ceramics, which is similar in appearance to natural teeth (Baldissara et al., 2010;Guazzato et al., 2005). However, cases of delaminating and chipping affecting the veneering porcelain have been reported for the molar area owing to the restrictions it poses on abutment cutting and high masticatory force (Rinke et al., 2013;Sailer et al., 2006Sailer et al., , 2007. Furthermore, there is a possibility that the accumulation of internal stress in the veneering porcelain firing cycles influences the marginal fit of the zirconia framework (Dittmer et al., 2009). ...
Layered-type zirconia disks, which offer color gradation from enamel to cervical shade, have been employed in recent years to replicate the shades of natural teeth. The layered structure is effective at replicating colors and has helped popularize monolithic zirconia restorations. However, the sintering shrinkage of zirconia is very large; thus, controlling the sintering distortion is very important. Thus, the objective of this study was to determine the influence exerted by the layered structure of the zirconia disk and the vertical milling area on the sintering distortion. An experimental fixed partial denture (FPD) was designed based on a 4-unit monolithic zirconia FPD. A single-composition (SC)-type disk with no shade and a single-composition-layered (SCL)-type disk with shade gradation were selected for this study. In particular, three milling areas, the top end of the disk (area I), vertical center (area II), and bottom end of the disk (area III), were investigated. Moreover, the sintering distortions generated by the experimental FPDs were measured. Results showed that sintering distortion in 4-unit monolithic zirconia FPDs occurred in all SC and SCL areas. Additionally, the sintering distortions were affected by the layered structure of the zirconia disks, the degree of which depended on the milling area (area I > area II > area III). Thus, when fabricating dental prosthesis using SCL zirconia disks, the milling area must be selected considering both the color adjustment and sintering distortion.
... The fracture of the veneering porcelain layer can be categorized from grade 1, for small reparable chippings, to a grade 3, for larger fractures that demand restoration replacement (Heintze and Rousson, 2010). Although clinical studies have shown that grades 1 and 2 (minor chippings) are more frequent than grade 3 (major chippings) (Rinke et al., 2013a(Rinke et al., , 2013bSailer et al., 2018;Sola-Ruiz et al., 2015;Teichmann et al., 2018), all types of fractures should be carefully addressed by researchers and clinicians to avoid subsequent bulk fracture of the remaining restoration. Chipping of the veneering layer applied over zirconia frameworks is influenced by the elastic and thermal properties of the veneering material that generates undesirable tensile stresses (Jikihara et al., 2019;Meira et al., 2013). ...
Objectives
To evaluate the edge chipping resistance (ReA) and the fracture toughness (KC) of 3Y-TZP bilayers produced with the following materials/processing combinations: fluorapatite glass-ceramic applied on zirconia using the traditional layering and hot-pressing (press-on) techniques; feldspathic porcelain using rapid layer technology (RLT); and lithium disilicate glass-ceramic using CAD-on method. The influence of the cooling rate (slow and fast) was analyzed for layering and hot-pressing.
Methods
Bilayer bars (25x4x2 mm) were made following manufacturers' instructions. The edge chipping test was performed in an universal testing machine, using a coupled Vickers indenter. ReA was calculated dividing the critical load at fracture by the edge distance. Fracture toughness was calculated by a regression fit with a fixed slope of 1.5 correlating the critical chipping load regarding edge distance and also with indentation fracture (IF) method. Data were statistically analyzed using ANOVA and Tukey's test (α = 5%).
Results
ReA and KC was significantly higher for the CAD-on bilayers. RLT showed intermediate ReA means, and layering and hot-pressing techniques showed the lowest ReA values. For both processing methods there was no effect of the cooling protocol on the ReA and fracture toughness.
Conclusions
There is a significant effect of the material/processing association on the edge chipping resistance and fracture toughness of the bilayers. There was no effect of the cooling protocol on the edge chipping resistance and fracture toughness for the specimens processed by both the layering and hot-pressing techniques.
... Larsson et al. (Larsson et al., 2006) bezeichneten die dichte Sinterung der Oxidkeramiken als Ursache für eine sehr starke Opazität, wo hingegen Silikatkeramiken transluzenter sind. Die Silikatkeramik gilt besonders im Frontzahnbereich als Mittel der Wahl, da sie sich an die Umgebungsfarbe adaptieren kann ("Chamäleon-Effekt") und lichtleitend sowie plaqueabweisend ist (Rinke, 2011 (Parma, 1960 ...
Versorgungen aus Keramik haben sich durch ihre überlegene Ästhetik, zweckmäßige Funktion sowie hohe Biokompatibilität und geringe Plaqueakkumulation durchgesetzt. Die Qualität von keramischem Zahnersatz wurde durch den inzwischen beinahe standardmäßigen Einsatz von computergestützter Fertigungstechnik maßgeblich gesteigert. Durch die Weiterentwicklung der Technik wurde außerdem die Herstellung hochfester und komplexer Metallkeramiken wie Zirkonoxidkeramik möglich. Sie weisen eine Biegefestigkeit von 900 bis 1200 MPa auf und sind deshalb als mehrspannige Vollkeramikrestauration für den Seitenzahnbereich oder für ganze Prothesengerüste freigegeben. Für gefräste Lithiumdisilikatkronen zeigten verschiedene klinische Studien eine zufriedenstellende Überlebensrate von 98 - 100% nach einem Beobachtungszeitraum von 2- 3 Jahren. Der größte Teil der Misserfolge war Frakturen geschuldet. Im Gegensatz zu monolithischen Lithiumdisilikatkeramiken unterscheiden sich polykristalline Metallkeramiken ästhetisch stark von der Lichtdurchlässigkeit natürlicher Zähne, weshalb für Einzelzahnkronen meist nur Gerüste aus Metallkeramiken hergestellt werden, die abschließend mit ästhetischen Glaskeramiken verblendet werden. So können die Vorteile aus Festigkeit und Ästhetik optimal miteinander kombiniert werden. Die größte Komplikation bei keramisch verblendeten Restaurationen mit Zirkonoxidgerüst sind Chipping-Frakturen. Dies betrifft vor allem die nicht-monolithischen Vollkeramiken. Ziel unserer Studie war es, 3-4- gliedrige Seitenzahnbrücken und Kronen aus mit Feldspatkeramik verblendetem Zirkonoxid in ihrem in-vivo Verhalten mit CAD/CAM gefertigten Lithiumdisilikatkronen zu vergleichen und ihre Abrasion über eine längere Zeit zu untersuchen.
... One aspect that should be considered in the case of a fixed denture could be the length of the reconstruction. Studies have shown a higher fracture rate as the length of the denture prosthesis increase [20][21][22][23]. ...
Introduction: Edentation is a major emergency and has an echo over the entire stomatognathic system. The treatment of partial edentation has undergone major changes in the last decades for multiple causes, including increasing the level of dental, medical education, introducing new techniques, methods, and materials, increasing the duration of retention of teeth on the arch.
Aim of the study: The aim of this study is to determine the degree of satisfaction of patients with a fixed prosthetic denture, to highlight the importance of communication between doctor and patient with repercussions on the results of prosthetic treatment, and evaluate the degree of awareness of oral health and oral hygiene practices.
Material and Method: For this study it was used a self-designed questionnaire, which explored both clinical and non-clinical dental services. The questionnaire consisted of three parts: first part (A) includes socio-demographic indices, part two (B) includes questions related to the doctor-patient relationship, and in the third part (C) the questionnaire asks questions regarding the general satisfaction of the patients with reference to the prosthetic tratament. The questionnaire also includes the material (s) from which the prosthetic denture is performed and the area of the edentation.
Results: The present study was performed on a batch of 117 people, 48 female, and 69 males between the ages of 21 and 60. Our results show that the majority of patients present metallic-ceramic dentures, located in most cases in the lateral area, and the majority of patients are satisfied with the prosthetic tratament. There were no patients complaining about the result of the tratament. Pacients are delighted by their relationship with medical staff.
Conclusions: The most important finding of this study states that a large proportion of patients showed a lack of knowledge regarding oral hygiene measures and the importance of maintaining a fixed prosthetic denture using a dental abutment. Also, the majority of the doctors did not pay attention to the post-treatment instructions regarding the maintenance of a fixed prosthetic denture.
... 21 Pelaez ve arkadaşları, 22 3 üyeli Lava restorasyonların 4 yıllık klinik takiplerini yaptıkları çalışmalarında, 20 restorasyonun hiçbirinde altyapı kırığı gözlenmediği, 2'sinde üstyapı kırığı gözlendiğini belirtmişlerdir. Rinke ve arkadaşları, 23 3-4 üyeli Cercon restorasyonların 7 yıllık klinik takibini yaptıkları çalışmalarında, 97 restorasyonun beşinde alt yapı kırığı, 23'ünde ise üstyapı kırığı gözlemlemişlerdir. Sulaiman ve arkadaşları24 2016 yılında yaptıkları çalışmada 5 yıllık klinik takip ile monolitik zirkonya restorasyonların başarısızlıklarını değerlendirmişlerdir. Toplam 39827 monolitik zirkonya restorasyon kaydı incelenmiş olup bunların 3731 tanesi anterior bölgede (1952 tek kron; 1799 köprü restorasyon); 36096 tanesi posterior bölgede (29808 tek kron; 6288 köprü restorasyon) bulunmaktadır. ...
... From this point of view, we observed that the absence of surface treatment (or the hypothesized use of a non-adhesive cementation protocol) when aging occurs (temperature changes and storage inducing dimensional expansion/contraction, residual stresses, damages at the interfacial zone, and luting agent hydrolysis) can strongly influence the mechanical fatigue performance of the set (FSZ restorations luted onto dentin analog), which confirms that surface treatments of the intaglio surface of FSZ restorations and adhesive cementation (using resin cement) is mandatory for stable fatigue behavior. Existing in vivo observations also confirm this assumption, as the use of conventional cement for zirconia ceramic cementation was related to an increased rate of retention loss (Rinke et al., 2013). Moreover, in vitro studies have demonstrated significantly lower fatigue resistance when YSZ restorations are cemented with non-adhesive approaches (Anami et al., 2016;Campos et al., 2017;Fraga et al., 2018;Guilardi et al., 2019). ...
This study evaluated the distinct conditioning effect of the intaglio surface of bonded fully-stabilized zirconia (FSZ) simplified restorations on the mechanical fatigue behavior of the set prior to and after aging. Ceramic disc shaped specimens (Ø= 10 mm and 1 mm thick) were randomly allocated into 14 groups considering: “surface treatments” (Ctrl: no-treatment; PM: universal primer; GLZ: low-fusing porcelain glaze; SNF: 5 nm SiO2 nanofilm deposition; AlOx: air-abrasion with aluminum oxide; SiC: air-abrasion with silica-coated aluminum oxide; 7%Si: air-abrasion with 7% silica-coated aluminum oxide); and “aging” (baseline: 24 h at 37 °C in water; or aged: 90 days at 37 °C in water + 12,000 thermal cycles). The discs were treated, luted with resin cement onto the dentin analog, subjected to aging or not, and then tested under a step-stress fatigue test at 20 Hz, 10,000 cycles/step, step-size of 100N starting at 200N, and proceeding until failure detection. Fractographic, topographic, surface roughness, contact angle, and atomic force microscopy analyzes were performed. The surface treatments at baseline led to statistically similar fatigue failure loads (953N–1313N), except for GLZ (1313N), which was significantly higher than 7%Si (953 N). Meanwhile, Ctrl had 40% pre-test failures (debonding) after aging, and therefore the worst fatigue performance (notable decrease in fatigue results), while all the other groups presented superior and statistically similar fatigue behavior (973–1271N). In fact, when considering baseline Vs aging conditions, stable fatigue results could only be noted when using surface treatments. In conclusion, internal surface treatments of FSZ ceramic restorations are mandatory for fatigue behavior stability after aging the restorative set, while non-treatment induced unstable results.
... Accordingly, the authors recommended to critically reassess the use of this type of cement. 31,32 Preparations for single crowns presented an average preparation angle of more than 26 degrees. 33 Therefore, it seems to be debatable if it is possible to respect the given preparation guidelines in everyday practice. ...
For several years, there has been a clear trend in the dental market towards monolithic tooth-colored restorations. In this context, further developments, particularly in the field of zirconia ceramics, have led to considerable improvement in the materials' optical properties. Modern zirconia materials can be divided into several cohorts, differing from each other with respect to their optical and mechanical properties. The knowledge about indications and limitations of each zirconia cohort is essential for a correct clinical application. Clinical long-term experience for the zirconia of the newest generations is still scarce and only in-vitro data are available. Despite all advancements, clinical long-term success remains closely linked to the specific indications, preparation, material selection, knowledge, and experience of the dental practitioner and dental technician, as well as an adequate luting mode and occlusal concept. Due to the high innovation rate within materials and CAD/CAM technology in general, clinicians and dental technicians need to be well informed in order to be able to work successfully with the various options.
... While 3mol% yttria stabilized zirconia polycrystal (3Y-TZP) is inferior as an aesthetic perspective, research has confirmed that it satisfies the demand as core material for ceramic restorations. The sound application and success rates of 3Y-TZP have been satisfactorily proven [4][5][6], with the survival rate of zirconia FDPs being similar to that of metal ceramics [7][8][9][10]. However, the successful outcome of FDPs depends on the material properties as well as the luting protocol. ...
Objective
The purpose of this study was to analyze the impact of plasma treatment and (universal adhesives) UAs on the bonding properties of zirconia.
Material and methods
Zirconia specimens (N = 744; n = 186/pretreatment) were prepared, highly polished, and pretreated: (i) plasma (oxygen plasma, 10s, 5 mm), (ii) airborne-particle abrasion (alumina, 50 μm, 0.05 MPa, 5 s, 10 mm), (iii) airborne-particle abrasion + plasma, and (iv) without pretreatment (highly polished surface). Surface roughness (Ra) and surface free energy (SFE) were measured (n = 6/pretreatment). Tensile bond strength (TBS) specimens (n = 180/pretreatment) were further divided (n = 18/conditioning): Clearfil Ceramic Primer (PCG), All-Bond Universal (ABU), Adhese Universal (AU), Clearfil Universal Bond (CUB), G-Premio Bond (GPB), Futurabond U (FBU), iBond Universal (IBU), One Coat 7 Universal (OCU), Scotchbond Universal (SBU), and no conditioning. PCG was luted with Panavia F2.0 and the remaining groups with DuoCem. After storage in distilled water (24 h; 37 °C) and thermocycling (5000×; 5 °C/55 °C), TBS was measured and fracture types (FTs) were determined. Data were analyzed using univariate ANOVA with a partial eta square (ƞP²), the Kruskal–Wallis H, the Mann–Whitney U, and the Chi² test (P < .05).
Results
Plasma treatment resulted in an increase of SFE but had no impact on Ra. Airborne-particle abrasion resulted in the highest Ra and a higher TBS when compared with plasma and non-treatment. SBU and AU obtained a higher TBS when compared with PCG. OCU, FBU, ABU, IBU, and GPB indicated comparable TBS to PCG. CUB revealed the lowest TBS.
Conclusions
Plasma treatment cannot substitute airborne-particle abrasion when bonding zirconia but MDP-containing adhesives are essential for successful clinical outcomes.
Clinical relevance
Airborne-particle abrasion with a low pressure (0.05 MPa) in combination with UAs promotes the clinical success of adhesively bonded zirconia restorations.
... Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) has been widely used as a material for prostheses owing to its biocompatibility and excellent mechanical properties. 1 Zirconia prostheses have shown a wide range of survival rate (81 -100%) in 5-year observation, which was reported to be associated with mechanical complications such as veneer chipping and loss of retention. [2][3][4] Loss of retention occurs more frequently in Y-TZP than in porcelain-fused metal prostheses. 5 Ortorp et al. 3 monitored monolithic zirconia prostheses for 5 years and insisted that loss of retention accounted for the highest percentage of total complications (30%). ...
PURPOSE
The effect of silica-based glass-ceramic liners on the tensile bond strength between zirconia and resin-based luting agent was evaluated and compared with the effect of 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing primers.
MATERIALS AND METHODS
Titanium abutments and zirconia crowns (n = 60) were fabricated, and the adhesive surfaces of the specimens were treated by airborne-particle abrasion. The specimens were divided into 5 groups based on surface treatment: a control group, 2 primer groups (MP: Monobond Plus; ZP: Z Prime Plus), and 2 liner groups (PL: P-containing Liner; PFL: P-free Liner). All specimens were cemented with self-adhesive resin-based luting agent. After 24-hour water storage and thermocycling (5,000 cycles, 5℃/55℃), the tensile bond strength was measured using a universal testing machine. Failure mode analysis and elemental analysis on the bonding interface were performed. The data were analyzed using Kruskal-Wallis test, Dunn's post hoc test, and Fisher's exact test.
RESULTS
The liner groups and primer groups showed significantly higher tensile bond strengths than that of the control group (P<.05). PFL showed a significantly higher tensile bond strength than the primer groups (P<.05). The percentage of mixed failure was higher in the primer groups than in the control group (P<.001), and all the specimens showed mixed failure in the liner groups (P<.001). A chemical reaction area was observed at the bonding interface between zirconia and liner.
CONCLUSION
The application of liner significantly increased the tensile bond strength between zirconia and resin-based luting agent. PFL was more effective than MDP-containing primers in improving the tensile bond strength with the resin-based luting agent.
... 41 Furthermore, clinical complications, eg, debonding and framework fracture, seem to occur more frequently in Y-TZP prostheses bonded with zinc phosphate than with composite cements. 20,43 ...
Purpose:
To evaluate the effect of different luting strategies on the fatigue failure load (FFL) and stress distribution of Y-TZP disks luted to epoxy resin substrate.
Materials and methods:
Y-TZP disks (diameter = 10 mm; thickness = 0.7 mm) were assigned to five groups according to the luting strategy (n = 15): CC: no zirconia surface treatment, composite cement; G_CC: application of a thin glaze layer on zirconia followed by hydrofluoric acid etching and silanization, composite cement; Al_CC: air abrasion of the zirconia surface with 125-µm Al2O3 particles, composite cement; Si_CC: tribochemical silica coating (30-µm SiO2 particles), composite cement; ZP: air abrasion of the zirconia surface with 125-µm Al2O3 particles, zinc-phosphate cement. The disks were luted to the epoxy resin substrate. The FFL was evaluated by the step-test method. The load was applied in stages of 10,000 cycles, starting with 600 N, followed by increments of 200 N. Samples were loaded until fracture or to a maximum of 100,000 cycles. FFL data were submitted to Kaplan-Meier (α = 0.05) and Weibull analyses. Conditions simulating a strong and a weak bond between Y-TZP and epoxy resin were evaluated in the finite element analysis (FEA).
Results:
Luting strategy influenced the FFL (p < 0.001) and the stress distribution of Y-TZP disks. Al_CC (2227 ± 149 N) and Si_CC (2133 ± 235 N) showed the highest FFL values, followed by CC (1800 ± 293 N) and G_CC (1280 ± 147 N), while ZP showed the lowest FFL value (680 ± 101 N). The highest Weibull modulus occurred in Al_CC (18.2). A strong bond reduced the tensile stress concentration in the Y-TZP luting surface, while a weak bond between Y-TZP and the epoxy resin favored the concentration of tensile stresses.
Conclusion:
Air abrasion with aluminum oxide and silica-coated alumina particles improves the FFL of bonded Y-TZP. Zinc-phosphate cement should be used very carefully in the cementation of zirconia restorations, since it results in lower values of FFL than composite cements.
... The published porcelain veneering fracture rate in clinical studies varies from 0% to 39% [22,49]. Eleven clinical studies report about framework fracture from 1% to 17.6% [24,29,[33][34][35][36][37]40,42,44,49]. Loss of retention was documented in only three clinical studies [26,33,46]. ...
Zirconia fixed prosthetic dentures are extensively used for replacing missing teeth. The primary objective of this systematic review was to gather and present the results of all in vitro studies and clinical trials conducted on zirconia fixed prosthetic dentures. This review concentrated exclusively on bilayered zirconia and monolithic fixed prosthetic dentures. As such this paper can act as a guideline for more comparable future experimental work on zirconia ceramics. Future studies must use a more systematic approach such as the uniform use of abutment material, material for simulating periodontal support, data about fracture strength before and after fatigue, number of cycles, information about position and size of the indenter. The new digital techniques with long-term follow-up are desirable in further clinical studies.
Purpose
To compare the failure rates and the prevalence of technical complications between full-coverage tooth-supported monolithic zirconia (MZ) and porcelain-veneered zirconia (PVZ) fixed dental prosthesis, based on a systematic literature review.
Methods
An electronic search was performed in three databases, supplemented by hand searching. Several statistical methods were used.
Results
Seventy-four publications reported 6370 restorations (4264 PVZ; 2106 MZ; 8200 abutment teeth; 3549 patients), followed up until 152 months. A total of 216 prostheses failed, and survival was statistically significant different between groups. PVZ had higher occurrence of complications than MZ; the difference was especially greater for either minor or major chipping. The difference in prevalence of either minor or major chipping was statistically significant for PVZ prostheses between cementation with glass ionomer and adhesive resin cement (higher), adhesive resin and resin-modified glass ionomer cement (RMGIC, higher), and between RMGIC (higher) and glass ionomer cement. For MZ the difference was significant only for minor chipping between RMGIC (higher) and adhesive resin cement. Abutment teeth to PVZ prostheses more often lost vitality. Decementation was not observed with RMGIC. Air abrasion did not seem to clinically decrease the decementation risk. The 5-year difference in the occurrence of minor or major chipping between MZ and PVZ prostheses was statistically significant, but nor for catastrophic fracture.
Conclusion
Tooth-supported PVZ prostheses present higher failure and complication rates than MZ prosthesis. The difference in complications is striking when it comes to chipping.
Clinical relevance
Awareness of the outcome differences between different types of zirconia prostheses is important for clinical practice.
Statement of problem
Completely veneered zirconia ceramic (ZC) fixed partial dentures (FPDs) have been reported to have a higher incidence of ceramic chipping than the standard metal-ceramic FPDs. However, data from comparative long-term studies are sparse.
Purpose
The purpose of this retrospective study was to compare the long-term survival, chipping-free survival, and success of ceramic-veneered high noble metal alloy (HN), base metal alloy (cobalt-chromium alloy) (CC), and ZC FPDs and to isolate risk factors for the incidence of failure, veneer chipping, and overall complications.
Material and methods
Data from 289 study participants (58.7% women; mean age, 57.97 ±11.51 years) provided with a total of 400 FPDs comprising 197 (49.3%) HN FPDs, 121 (30.3%) CC FPDs, and 82 (20.5%) ZC FPDs fabricated from presintered 3 mol% yttria-stabilized zirconia (mean time of service, 6.85 ±3.25 years) were evaluated. Of these, 278 (69.5%) FPDs were provided by dentists and 122 (30.5%) by dental students. Five- and 10-year survival, chipping-free survival, and success rates were calculated using the Kaplan–Meier method and compared with the log-rank test. Risk factors were assessed using Cox regression analysis. The study was exploratory, so all P values were considered exploratory and descriptive.
Results
The 5- and 10-year survival rates were 94.7% and 77.8% for HN, 93.7% and 81.2% for CC, and 92.9% and 53.3% for ZC FPDs, respectively, indicating no clear difference in survival among the framework materials. The 5- and 10-year chipping-free rates were 94.1% and 82.8% for HN, 96.1% and 78.9% for CC, and 82.6% and 62.2% for ZC FPDs, respectively, indicating a difference between HN and ZC, and CC and ZC restorations. The 5- and 10-year success rates were 83.7% and 55.3% for HN, 86.5% and 51.4% for CC, and 68.9% and 30.2% for ZC FPDs, respectively, indicating a difference between HN and ZC, and CC and ZC restorations. The Cox regression model indicated framework material as an influencing risk factor for success, and this influence persisted when chipping was investigated. Compared with zirconia, the use of a metal alloy reduced the risk of chipping or the occurrence of complications by up to one-third.
Conclusions
All FPDs showed high 5-year survival rates and acceptable 10-year survival rates with no strong differences among the materials. Higher success and chipping-free rates were observed for both HN and CC restorations compared with ZC restorations. Metal frameworks had a lower risk for complications or veneer chipping than zirconia frameworks.
Objectives:To evaluate of the effectiveness of rehabilitation in patients following mandibulectomy and free fibula flap reconstruction with further endosteal implants. Materials and Metods: The patient cohort consisted of 27 patients years (14 males and 13 females) with lower jaw defects due to resection for tumors, were reconstructed with fibula-free flaps in a 6-year period (2015-2020). All patients underwent a thorough clinical laboratory, radiological examination according to a generally accepted scheme. Patients were evaluated by preoperative and postoperative outcome using computed tomography scan evaluation. The surgical procedure included: Segmentar resection of the lower jaw, reconstruction with fibula free flap. The implants were evaluated with measures of Resonance Frequency Analysis (RFA) during the follow-up periods using Osstell Mentor at time of implant placement, after 3 months. The mean RFA recordings of all 134 implants were 65 ISQ at implant placement respectively 73 ISQ after 3 months. After 4-6 months of healing, 152 dental implants were placed in non-irradiated fibular bone. Dental prosthetic rehabilitation was performed after 3-4 months of submerged healing. Patients had received implant-bridge and hybrid denture that provided ideal facial balance and occlusion. Results:Postoperative clinical and radiographic controls were made regularly, the criteria for implant success were assessed.With dynamic observation, clinical and radiological indices were stable, of the 152 implants installed, 2 failed to osseointegrate and 5 after years of loading (peri-implantitis). Success rate of implants 5 years after was 96.1%. Conclusion:The reconstruction of the lower jaw defects after ablation of tumors with fibular flaps is a reliable method with good long-term results. In all 27 patients, fibula flaps provided adequate bone stock for implant placement. Implants placed in the reconstructed areas were demonstrated to integrate normally. The results showed that implant treatment is effective to improve patients‘ masticatory efficiency and an acceptable quality of life to the patient
Purpose: To evaluate the survival of implants, the success of prosthetics of implant-supported reconstructions based on monolithic zirconium dioxide, functioning up to 5 years. Materials and Methods: In this study 87 patients were participated referred in need of full arch implant-supported reconstructions in maxilla, mandible or both. All patients underwent a thorough clinical examination according to a generally accepted scheme. After the diagnostic workup was completed, a treatment plan was developed by using a cone beam computed tomography and software system. Using surgical guides 46 patients' dental implants were installed. Postoperative clinical and radiological monitoring was regularly conducted, and criteria for thesuccess of implantation and success of prosthetics of implant-supported reconstructions were evaluated 642 implants (6 to 8 dental implants in the edentulous arches) were installed for monolithic zirconia full arch reconstructions.prosthodontic treatment was performed 3 to 6 months after implants healing time. Digitaltechnologies were included in the work flow with the laboratory scanning of the master casts andCAD/CAM manufacturing software. The monolithic zirconia block were milled using CAD/CAM software according to the manufacturer‘s specifications and then a monolithic zirconia restorations sintering. Outcome measures were: Implant success; prosthesis success; complications and marginal bone levels. Results: No intra-operative or immediate post-operative complications were noted. During a 3-year observation fracture of the monolithic zirconia or any other mechanical complications of prostheses, no registered, screws fractured in 3 prosthesis was observed over the 3-year study period. Conclusion: Our studies have shown good aesthetic, functional and mechanical properties of monolithic zirconia restorations and fewer complications
Due to the increasing demand from patients and dentists for highly aesthetic and strong, metal-free restorations there has been a rapid increase in research into dental CAD CAM technique and zirconia based restorations over the last decade. Such new technology has the potential to take the place of conventional techniques and materials for fabricating indirect dental restorations in the future.
In this PhD thesis, five laboratory studies were designed to investigate zirconia bridges constructed using dental CAD CAM. The studies concentrated on:
1. Ideal force applied by dentists for cementing zirconia bridges and the impact on seating.
2. The effect of firing cycles and zirconia thickness on the fit of zirconia bridges.
3. The effect of span length on the fit of three and four unit all zirconia bridges.
4. The effect of veneering on the strength of three unit zirconia bridges.
5. The fit of three unit all zirconia bridges produced by digital and conventional techniques.
For these laboratory studies an ideal three unit (and four unit for study 3) fixed-fixed all ceramic bridge preparation was carried out on two plastic teeth and all SLA models and zirconia based bridges were made using the Lava COS and Lava™ CAD CAM system (3M, ESPE).
In addition to the laboratory studies, a clinical audit was carried out to assess satisfaction (dentist, dental technician and patient) with zirconia based restorations (through a series of questionnaires) made and fitted at Dundee Dental Hospital and School. In addition, as part of this audit a simple cost analysis was carried out to explore the differences in cost between zirconia based restorations and high fusing gold alloy based metal ceramic restorations.
Four of the studies (studies 1, 2, 3 and 5) investigated the internal and marginal fit of the zirconia based restorations under differing laboratory and clinical procedures and conditions. It was found that the seating force used to cement a zirconia based bridge had no impact upon fit (Study 1). Whilst the thickness of zirconia (all-zirconia bridge and un-veneered zirconia framework) did not affect the fit of the restoration, veneering the framework did lead to a statistically significant deterioration in fit (Study 2). Although leading to a poorer fit veneering did have a positive effect in strengthening the zirconia framework, but neither un-veneered nor veneered frameworks were as strong as monolithic/all zirconia bridges (Study 4). Despite the high shrinkage during post milling sintering and the potential for greater distortion on longer span bridges, the longer span bridges investigated in Study 3 did not impact upon fit. In study 1, 2, 3 and 4 the Lava COS intra-oral scanner was used to create a digital impression of the tooth preparations and study 5 confirmed that the fit of bridges made from these impressions were better than those made using conventional addition cured silicone putty and wash impressions (Study 5). The results of the questionnaires used in the audit revealed high satisfaction rates with all stake holders and the cost analysis showed that producing zirconia based restorations can be five to six times cheaper than conventional gold based restorations.
Despite the variations in fit which were found in Studies 2 and 5, all bridges produced were within what would be regarded as clinically acceptable and comparable to those produced with more traditional techniques.
Background:
Evaluation of the different causes listed in literature for the rate of success of Zirconia based restorations.
Material and methods:
With the help of PRISMA guidelines , this Systematic review was carried out. For a time span of 18 years that is from 2003 to 2020, articles were searched using three electronic data bases which are PubMed , Cochrane Library and Sciencedirect. The selected 27 articles which included the in vivo as well as the in vitro studies presented the performance of zirconia-based prosthetic restorations. The studies also stated the commonest reason for failure which ultimately depicted the rate of success of the fixed dental prosthesis. Due to heterogeneity of gathered information , meta analysis could not be carried out.
Results:
Failure of bond between veneer material and zirconia sub-structure could be related to the cause of fracture of veneering porcelain hypothetically.
Conclusions:
Mechanical connection and building up of compressive strength due to thermal contraction at the time of cooling after sintering process is the reason for the bond developed amongst the two materials. Key words:Zirconia based restorations, zirconia failure cause.
Background
Nowadays, the esthetics demand is continuously increasing; therefore, metal-free materials are widely used, like a zirconia-based ceramic, which is conveniently fabricated via computer-aided design and computer-aided manufacturing (CAD/CAM) system for restorations from single to full mouth rehabilitation.
Objective
This study evaluated the effect of pre-curing pressure on the shear bond strength of zirconia to the resin cement.
Methods
A total of sixty-three sandblasted cylindrical zirconia mounted in autopolymerizing resin were randomly assigned to three groups; Group 1: no treatment (control), Group 2: negative pressure, and Group 3: positive pressure to resin cement after resin cement application and resin composite columns bonded to zirconia. Thirty-three of the samples were stored in distilled water at 37 °C for 24 hr before the shear bond strength test for thirty samples and three samples were cross-sectionally cut for interfacial observation with FESEM. Another thirty samples were thermocycled for 5,000 cycles in distilled water at 5°C to 55 °C before testing. The shear bond strength and failure mode were evaluated. Examination of the bonding interface was also done.
Results
The results were analyzed using two-way ANOVA. The means of shear bond strength of non-thermocycle of the control group were 8.01 ±1.74 MPa, 9.10 ±1.90 MPa, and 9.14 ±2.58 MPa, whereas that of thermocycle group were 5.71 ±0.84 MPa, 5.53 ±0.68 MPa, and 5.68 ±0.77 MPa in zero pressure group, negative pressure group, and positive pressure group, respectively. It showed no statistically significant differences in shear bond strength in all pressure groups (p > 0.05). The pre-curing pressure did not influence the shear bond strength of the zirconia and resin cement.
Conclusion
There was no difference in the shear bond strength between the pressure groups and the no treatment control group. The positive and negative pressure did not influence the shear bond strength of the zirconia and resin cement.
In the update of the S3 guideline "All-ceramic single crowns and fixed dental prostheses" (AWMF Reg. No. 083-012) published in June 2021, new scientific evidence was incorporated into the guideline first published in 2014. The guideline established a broadly consented, evidence-based framework within which the use of tooth-supported all-ceramic restorations offers comparable long-term clinical outcomes to metal-based crowns and fixed dental prostheses (FDPs). In the updated version (version 2.0), all chapters have been reviewed with regard to new research findings, backgrounds have been newly discussed, and numerous recommendations have been updated with regard to indications and localization. In the process, the recommendation grading of individual materials was adjusted on the basis of new literature. Recommendations on materials that are no longer on the market (alumina ceramics) were removed and recommendations on new materials and applications were added (zirco-nium oxide ceramics [3Y-TZP] monolithic; zirconium oxide ceramics [4Y-, 5Y-TZP and combinations with these]; resin-matrix ceramics; lithium silicate/ phosphate glass-ceramics). Recommendations on endocrowns were also made for the first time. In addition, the questions regarding the treatment of brux-ism patients with all-ceramic restorations as well as material-specific manufacturing recommendations were re-evaluated. The main recommendations are listed in this article, the key innovations are emphasized, and the considerations of the guideline group in arriving at the recommendations are summarized. All recommendations as well as complete references can be found in the long version of the German S3 guideline [11]. Update of the S3 guideline "All-ceramic single crowns and fixed dental prostheses"-current evidence-based recommendations.
Background
With the constantly increasing demand for metal-free solutions in dental therapy, numerous ceramic restorations have found their way into everyday clinical practice, but long-term clinical data are limited.
Objective
The aim of this prospective clinical study was to evaluate three- and four-unit fixed partial dentures in the posterior region made of zirconium dioxide frameworks veneered with feldspathic porcelain after 10 years in clinical use.
Methods
Based on the two studies published in 2009 and 2012, in which the all-ceramic FDPs were evaluated after 3 and 5 years of function, a clinical evaluation of a total of 17 restorations after 10 years with regard to their condition and long-term stability was carried out in the course of this study. The restorations were fabricated using feldspathic-ceramic-veneered, yttria-stabilized, tetragonal zirconium dioxide as the framework material. The data collection was based on modified CDA criteria and included, for example, the shape, shade, surface condition, and the success and survival rates of the restorations.
Results
The all-ceramic prostheses embodied excellent biocompatibility and color reproduction. As a result of an increased incidence of chipping fractures, the success rate was 60%. The survival rate, however, was 88.2 %, as 2 of the 17 restorations were lost.
Conclusion
All-ceramic concepts for FDP constructions in the posterior region achieved satisfactory results in terms of durability after 10 years. The main problem was chipping, as has been generally recognized. Nevertheless, the materials were characterized by excellent aesthetics and biocompatibility, which ultimately makes them a good alternative to conventional restorative options.
Statement of problem:
Monolithic zirconia restorations have been evaluated with in vitro studies, but limited clinical evidence of their longevity and reliability is available.
Purpose:
The purpose of this clinical study was to evaluate the clinical performance of posterior multiunit glazed monolithic zirconia fixed dental prostheses.
Material and methods:
A total of 20 participants received 33 monolithic posterior zirconia fixed dental prostheses (Zolid white; Amann Girrbach AG) with minimally invasive preparations. Bilaterally supported fixed dental prostheses with a connector area of at least 9 mm2 were luted with resin-modified glass ionomer cement. The clinical evaluations were performed after 1 week, 6 months, and then annually after completion of the treatment. The biologic outcomes were evaluated by assessing the pocket depth, attachment level, plaque control, bleeding on probing, caries, and tooth vitality. Esthetics and the functional performance of the prostheses (color match, cavosurface marginal discoloration, anatomic form, marginal adaptation) were evaluated as per the rating scales of Cvar and Ryge. An analysis of survival was made by using the Kaplan-Meier method.
Results:
After 39.8 ±16.7 months of observation, the overall survival rate of the monolithic zirconia multiunit posterior prostheses was 93.9%. No caries were found on the abutment teeth, signs of gingivitis were noted in 1 participant after 24 months, and increased probing depths of the abutment teeth were detected in 5 prostheses (15.1%). No loss of retention was detected. Two prostheses had to be replaced: 1 because of a biologic complication and 1 because of a technical complication. The remaining 31 prostheses received Alfa scores for marginal adaptation, cavosurface marginal discoloration, and caries. Twenty-seven (87.1%) prostheses were rated as Alfa and 4 (12.9%) as Bravo for anatomic form. The color match was noted as Alfa in 15 (48.3%) prostheses, and 16 (51.6%) were rated as Bravo.
Conclusions:
Monolithic zirconia restorations demonstrated a reliable treatment option after medium-term clinical use for the replacement of missing posterior teeth.
1 Summary Aims The current situation of an ascertained scarceness of qualified scientific evidence for the long-term survival of all-ceramic zirconia bridges was the starting point that triggered the following study of a „10-year clinical evaluation of zirconia posterior FPD’s“. The aim of this investigation was to document the condition of tripartite and quadrinominal LAVA™-zirconia-bridges in the posterior region after a period of ten years in use in order to be able to make a statement about the robustness and resistance to wear and tear of this specific form of restauration in the long run. A three-dimensional white light scanner (ATOS II) had been used to document the abrasion of ceramics and to ensure a profound evaluation of all data. Methods The first part of this work deals with the clinical evaluation of zirconia-bridges in the posterior region. The ceramics have been judged by means of modified CDA criteria. Besides form, colour and surface texture also success rate and survival rate of the restaurations were recorded. In the second part full-ceramic bridges were ex-amined by a method established at the Friedrich-Alexander-University Erlangen Nürnberg - Zahnklinik 2 – Dental Prosthetics. A three-dimensional white light scan-ner (ATOS II) demonstrated most clearly the exact degree of abrasion. Here as well the occlusal volume decrease as the maximum loss of material within ten years could be visually captured and evaluated. Results First of all clinical evaluation has proved an excellent biocompatibility of full-ceramics. Furthermore the material convinced with its natural, full-scale colour re-production. However, the brittleness of the material often led to „chipping frac-tures“. After 10 years of use the success rate for all-ceramics in a follow up- exami-nation was at 60% whereas the survival rate could be specified by 88,2%. This cor-responds with 15 out of 17 all-ceramic bridges investigated. With the help of ATOS II an increasing loss of material could be detected during the investigation period. Apart from that abrasion differed between the premolar and molar parts of bridges. Over the whole period of examination molar parts showed a more significant loss of material. The maximum abrasion value could be determined between -0,278 mm for premolar and -0,435 mm for molar parts. Conclusion Based on the present study all-ceramic systems like LAVA™ (3M ESPE) used as bridge construction in the posterior region were certified satisfactory results as far as their durability is concerned. The main problem which caused the breakdown of this full-ceramic system was the appearance of the so-called „chipping“, a bursting and peeling of the ceramic cover. Patients showed themselves equally convinced of the biocompatibility of full-ceramic restaurations and the aesthetic effect as the doctors treating. As far as form, colour, plaque accumulation and the reaction of organic texture were concerned ceramics achieved high satisfaction. Nevertheless this sur-vey is inclined to recommend all-ceramic zirconia bridges in the posterior region only in a restricted way. The further technical development in the field of ceramics, especially the production of monolithic oxide ceramic may possibly bring about once more an increased durability here. Though, there is not yet enough data in this field which might allow a profound final judgement.
Purpose:
To evaluate the clinical performance and survival rate of posterior monolithic zirconia fixed partial dentures over a 2-year period.
Material and methods:
A total of 20 patients, requiring 20 posterior fixed partial dentures were included in the study. Tooth preparations were scanned, and restorations were milled and cemented with a resin cement. The restorations were assessed for the quality of the surface and the color, anatomical form and marginal integrity. Periodontal status was assessed by determining the plaque index, gingival index, pocket depth, and margin index of the abutment teeth. Data were statistically analyzed using the Friedman and the Wilcoxon signed-rank tests with the Bonferroni correction.
Results:
The survival rate at 2 years was 100%, and no biological or technical complications were observed. All restorations were assessed as satisfactory. The results obtained for gingival index and plaque index were better at 2 years follow-up, than at baseline. The margin index remained stable throughout the follow-up period. No differences in periodontal parameters were observed between abutment and control teeth.
Conclusions:
The high survival rate after 2 years suggest that monolithic zirconia may be an acceptable alternative to metal-ceramic and veneered zirconia restorations in the posterior region. Additional long-term, controlled studies are necessary to confirm the results.
Objective
To investigate the shear bond strength (SBS) of a glass ionomer (GI) cement, an 10‐methacryloyloxy‐decyl dihydrogen phosphate (MDP)‐based adhesive resin cement (MDP‐based AC), an MDP‐based self‐adhesive resin cement (MDP‐based SAC), an MDP‐free self‐adhesive resin cement (MDP‐free SAC), and a resin‐modified GI (RMGI) cement to a 3 mol% yttria‐stabilized (3Y‐TZP) and a 5 mol% yttria partially stabilized zirconia (5Y‐PSZ).
Materials and methods
Fifty blocks were produced using 3Y‐TZP and 5Y‐PSZ, assigned to subgroups based on the five cements investigated (n = 10) and luted to cylindrical specimens of the same substrate. Each specimen was loaded in a SBS apparatus to failure. Mean SBS (MPa) values and standard deviations were calculated. Data were analyzed using a two‐way analysis of variance and Tukey tests (α = .05). Failed specimens were subjected to fractographic analysis.
Results
MDP‐based AC and MDP‐based SAC cements displayed the highest SBS values with both the substrates; GI cement showed the lowest. RMGI and MDP‐free SAC cements performed better with 3Y‐TZP than with 5Y‐PSZ. Fractographic analysis revealed only adhesive and mixed failures.
Conclusions
MDP‐based AC and MDP‐based SAC cements are suitable for both 3Y‐TZP and 5Y‐PSZ. MDP‐free SAC and RMGI cements are adequate choices for 3Y‐TZP, but seem less effective with 5Y‐PSZ.
Clinical significance
MDP‐based SACs appear to be as reliable as MDP‐based ACs for both 3Y‐TZP and 5Y‐PSZ cementation. Specifically, for 5Y‐PSZ cementation, resin‐based MDP‐free SACs do not seem to guarantee predictable results in terms of SBS.
Objectives
the purpose of the present prospective trial was to evaluate the clinical performance of posterior 3-unit zirconia-based fixed dental prostheses (FDPs) after 14 years of clinical function.
Methods
thirty-seven patients needing to replace either premolars or molars were involved and 48 FDPs were fabricated (Procera Zirconia, Nobel Biocare AB). Frameworks with a9 mm² cross section of the connectors and 0.6 mm minimum thickness of the retainers were made by means of Procera Forte CAD-CAM System (Nobel Biocare AB). The patients were recalled after 6 and 12 months and then yearly up to a total follow-up of 14 years. Two independent survival curves for patients wearing 1 or 2 FDPs were calculated by means of Kaplan-Meier analysis and a log-rank test was performed in order to compare these curves. The United States Public Health Service criteria were used to examine technical and esthetic outcomes. The biological examination was performed evaluating plaque control, pocket depth, attachment level, bleeding on probing at both abutments and contralateral teeth and evaluated by means of the Wilcoxon test (p < 0.05) between the baseline and the 14-year follow-up.
Results
descriptive statistics resulted in 91% and 99% cumulative survival rates for patients wearing 1 and 2 FDPs, respectively. There were no significant differences in periodontal parameters between control and test teeth. Both function and esthetic results were successful for FDPs over a 14-year follow-up period.
Conclusions
the results of this prospective clinical study confirmed the effectiveness of zirconia as a clinical option to fabricate short-span posterior FDPs.
Clinical significance: within the limitations of the present prospective clinical study, zirconia-based three-unit fixed dental prostheses perform satisfactorily on long term, in posterior areas and in patients with standard biomechanical conditions.
Objective:
In the past, discrepancies between laboratory results and clinical behavior have been observed for all-ceramic restorations. This analysis of fracture resistance of zirconia-based inlay-retained fixed partial dentures (IRFPDs) aimed at identifying correlations between an in-vitro test setup and the clinical situation. The effects of tooth material, tooth mobility, restoration design, load direction, and different cements were taken into account.
Methods:
The in-vitro test model and IRFPD were reverse engineered (Geomagic DesignX) and meshed predominantly with hexahedral elements (approx. 230,000 elements). Homogenous, linear-elastic behavior was assumed for all materials. On the basis of the calculated stresses (ANSYS 18.2) and already known strength distributions for the restorative materials fracture resistance of the complete restoration and force at initial damage (fracture within the veneer) was estimated on the basis of the principal stress hypothesis. Differences depending on the assumed clinical situation and effects of different variables on fracture resistance were evaluated.
Results:
All variables tested in the finite element analysis affected the calculated fracture resistance of the IRFPD. Use of resin teeth led to an underestimation of fracture resistance by up to -57%, whereas fracture resistance of IRFPDs on metal abutment teeth was close to the clinical reference (-6% to +15%). Good correlation between the clinical scenario and that using metal teeth could only be achieved when the natural resilience of the abutment teeth was simulated.
Significance:
When testing fracture resistance of zirconia-based IRFPDs, metal abutment teeth in combination with simulated tooth resilience can reflect the clinical situation accurately.
Rapid Layer Technology (RLT) uses computer‐aided design/computer‐aided manufacturing (CAD/CAM) to manufacture a veneer layer that is adhesively bonded to the zirconia framework, avoiding firing steps during the fabrication process and thus preventing build‐up of residual stresses. This work studied, using sliding contact fatigue, the in vitro lifetime of restorations produced using RLT compared with restorations produced using conventional veneering techniques. Zirconia copings were veneered with a conventional hand‐layering method (VM9) using a fast (n = 16) or a slow (n = 16) cooling protocol, or with RLT. For the latter, the veneers were CAD/CAM fabricated using a feldspathic reinforced‐glass (Vitablocs Mark II; n = 16) or a polymer‐infiltrated reinforced‐glass network (Enamic; n = 16) and adhesively bonded to the zirconia frameworks. Crowns thus obtained were submitted to sliding contact fatigue against a steatite indenter in a chewing simulator until failure. A Kaplan–Meier survival analysis was conducted. None of the hand‐layered restorations survived after a 2 × 10⁶‐cycle interval, whereas no fractures in the RLT groups were observed. Vitablocs Mark II veneers survived for a longer testing period (3.5 × 10⁶ cycles) than their Enamic counterparts (2.5 × 10⁶ cycles) owing to their superior wear behavior. The RLT represents an efficient method to veneer zirconia frameworks by reducing processing steps and, more importantly, increasing the lifetime of the restorations.
The aim of this review was to systematically evaluate and compare the frequency of veneer chipping and core fracture of zirconia fixed dental prostheses (FDPs) and porcelain-fused-to-metal (PFM) FDPs and determine possible influencing factors.
The SCOPUS database and International Association of Dental Research abstracts were searched for clinical studies involving zirconia and PFM FDPs. Furthermore, studies that were integrated into systematic reviews on PFM FDPs were also evaluated. The principle investigators of any clinical studies on zirconia FDPs were contacted to provide additional information. Based on the available information for each FDP, a data file was constructed. Veneer chipping was divided into three grades (grade 1 = polishing, grade 2 = repair, grade 3 = replacement). To assess the frequency of veneer chipping and possible influencing factors, a piecewise exponential model was used to adjust for a study effect.
None of the studies on PFM FDPs (reviews and additional searching) sufficiently satisfied the criteria of this review to be included. Thirteen clinical studies on zirconia FDPs and two studies that investigated both zirconia and PFM FDPs were identified. These studies involved 664 zirconia and 134 PFM FDPs at baseline. Follow-up data were available for 595 zirconia and 127 PFM FDPs. The mean observation period was approximately 3 years for both groups. The frequency of core fracture was less than 1% in the zirconia group and 0% in the PFM group. When all studies were included, 142 veneer chippings were recorded for zirconia FDPs (24%) and 43 for PFM FDPs (34%). However, the studies differed extensively with regard to veneer chipping of zirconia: 85% of all chippings occurred in 4 studies, and 43% of all chippings included zirconia FDPs. If only studies that evaluated both types of core materials were included, the frequency of chipping was 54% for the zirconia-supported FDPs and 34% for PFM FDPs. When adjusting the survival rate for the study effect, the difference between zirconia and PFM FDPs was statistically significant for all grades of chippings (P = .001), as well as for chipping grade 3 (P = .02). If all grades of veneer chippings were taken into account, the survival of PFM FDPs was 97%, while the survival rate of the zirconia FDPs was 90% after 3 years for a typical study. For both PFM and zirconia FDPs, the frequency of grades 1 and 2 veneer chippings was considerably higher than grade 3. Veneer chipping was significantly less frequent in pressed materials than in hand-layered materials, both for zirconia and PFM FDPs (P = .04).
Since the frequency of veneer chipping was significantly higher in the zirconia FDPs than PFM FDPs, and as refined processing procedures have started to yield better results in the laboratory, new clinical studies with these new procedures must confirm whether the frequency of veneer chipping can be reduced to the level of PFM.
Zirconium dioxide (zirconia) ceramics are currently used for fixed restorations as a framework material due to their mechanical and optical properties. This review article describes the current status of zirconia-based fixed restorations, including results of current in vitro studies and the clinical performance of these restorations. Adaptation of zirconia-based restorations fabricated with CAD/CAM technology is within an acceptable range to meet clinical requirements. In terms of fracture resistance, zirconia-based fixed partial dentures (FPDs) have the potential to withstand physiological occlusal forces applied in the posterior region, and therefore provide interesting alternatives to metal-ceramic restorations. Clinical evaluations have indicated an excellent clinical survival of zirconia-based FPDs and crown restorations. However, some clinical studies have revealed a high incidence of chipping of veneered porcelain. Full-coverage zirconia-based restorations with adequate retention do not require resin bonding for definitive cementation. Resin bonding, however, may be advantageous in certain clinical situations and is a necessity for bonded restorations, such as resin-bonded FPDs. Combined surface treatment using airborne particle abrasion and specific adhesives with a hydrophobic phosphate monomer are currently reliable for bonding to zirconia ceramics. Further clinical and in vitro studies are needed to obtain long-term clinical information on zirconia-based restorations.
The interest of dental research in metal-free restorations has been rising in the last 20 years following the introduction of innovative all-ceramic materials in the daily practice. In particular, high strength ceramics and related CAD/CAM techniques have widely increased the clinical indications of metal-free prostheses, showing more favourable mechanical characteristics compared to the early ceramic materials. The purpose of the present paper is providing a brief review on the all-ceramic dental materials, evaluating pros and cons in the light of the most recent scientific results and of the authors' clinical experience.
A structured review of the literature was given on the basis of medical and engineering papers published in the last decades on the use of dental ceramics and zirconia in particular. The experimental and clinical findings of the most relevant researches were reported.
Zirconia is one of the most promising restorative materials, because it yields very favourable mechanical properties and reasonable esthetic. Several in vitro and in vivo investigations reported suitable strength and mechanical performances of zirconia, compatible with clinical serviceability as a framework material for both single crowns and short-span fixed partial dentures. However, clinical results are not comparable, at the moment, with conventional metal-ceramic restorations, neither is there sufficient long-term data for validating the clinical potential of zirconia in the long run.
The use of zirconia frameworks for long-span fixed partial dentures or for implant-supported restorations is currently under evaluation and further in vivo, long-term clinical studies will be needed to provide scientific evidence for drawing solid guidelines.
In this prospective clinical study, the performance of three- and four-unit fixed partial dentures (FPDs) with frameworks fabricated of yttria partially stabilized zirconia was determined after a mean observation period of 50 months. The study focused on the survival of the restoration (in situ criterion) and the success of the ceramic veneers (no defect).
Seventy-five patients with a maximum of two missing teeth and an antagonistic dentition were treated at the Department of Prosthodontics, University of Goettigen, with 99 posterior FPDs. Fifty-one specimens (experimental group) were veneered with an experimental ceramic suitable for titanium and zirconia frameworks (thermal expansion coefficient [TEC]: 8.5 microm/m*K); 48 restorations (Ceram-S group) were veneered with a commercially available low-fusing ceramic optimized for zirconia frameworks (TEC: 9.5 microm/m*K). All restorations were luted with zinc-phosphate cement. Statistical analysis was performed according to the Kaplan-Meier method; time-dependent success rates of the different types of ceramic veneers were analyzed using the log-rank test.
Seven restorations were lost: 4 due to technical complications and 3 due to biologic complications. The overall survival rate after 48 months was 94% (Kaplan-Meier analysis). Twenty-three events required clinical intervention for restoration maintenance: 13 ceramic veneer chippings (polishing), 6 losses of retention (recementation), 3 caries lesions (filling therapy), and 1 loss of vitality (endodontic treatment). Between the two groups of veneering materials, no significant difference in the probability for success was determined (log-rank test, P=.81).
Within a mean observation period of 4 years, sufficient survival rates for zirconia-based posterior FPDs could be verified. The main complications included fracture of the ceramic veneering material and decementation, which occurred mainly in the mandible.
The aim of this study was to test whether posterior fixed dental prostheses (FDPs) with zirconia frameworks exhibit similar survival rates and technical and biologic outcomes as those with metal frameworks.
Fifty-nine patients in need of 76 FDPs replacing one to three posterior teeth (molars and premolars) were included in the study. The three- to five-unit FDPs were randomly assigned to 38 zirconia-ceramic and 38 metal-ceramic FDPs. At baseline, 6 months, and 1 to 3 years after cementation, the technical outcome of the reconstructions was examined using the United States Public Health Service (USPHS) criteria. The biologic outcome was analyzed at test (abutment) and control (contralateral) teeth by assessing: probing pocket depth (PPD), probing attachment level (PAL), plaque control record (PCR), bleeding on probing (BOP), and tooth vitality. Radiographs of the FDPs were made. Statistical analysis was performed by applying Kaplan-Meier, Pearson chi-square, Fisher exact, and Mann-Whitney U tests.
Fifty-three patients with 67 FDPs (36 zirconia-ceramic, 31 metal-ceramic) were examined after a mean observation period of 40.3 +/- 2.8 months. Six patients with 9 FDPs were lost to follow-up. The survival of both kinds of FDPs was 100%. No significant differences regarding the technical and biologic outcomes were found. Minor chipping of the veneering ceramic was found in 25% of the zirconia-ceramic and 19.4% of the metal-ceramic FDPs. Extended fracturing of the veneering ceramic occurred solely in zirconia-ceramic FDPs (C: 8.6%, D: 2.8% [USPHS criteria]). Few biologic complications were found. Both types of FDPs rendered the same mean values for the biologic parameters (mean PPD, PCR, and BOP for zirconia-ceramic FDPs = 2.4 +/- 0.3, 0.1 +/- 0.1, and 0.3 +/- 0.2, respectively; mean PPD, PCR, and BOP for metal-ceramic FDPs = 2.4 +/- 0.3, 0.1 +/- 0.1, and 0.3 +/- 0.2, respectively).
Zirconia-ceramic FDPs exhibited a similar survival rate to metal-ceramic FDPs at 3 years of function.
The aim of this prospective clinical cohort study was to determine the success rate of 3- to 5-unit zirconia frameworks for posterior fixed partial dentures (FPDs) after 5 years of clinical observation.
Forty-five patients who needed at least 1 FPD to replace 1 to 3 posterior teeth were included in the study. Fifty-seven 3- to 5-unit FPDs with zirconia frameworks were cemented with 1 of 2 resin cements (Variolink or Panavia TC). The following parameters were evaluated at baseline, after 6 months, and 1 to 5 years after cementation at test (abutments) and control (contralateral) teeth: probing pocket depth, probing attachment level, Plaque Index, bleeding on probing, and tooth vitality. Intraoral radiographs of the FPDs were taken. Statistical analysis was performed using descriptive statistics, Kaplan-Meier survival analysis, and the McNemar test.
Twenty-seven patients with 33 zirconia FPDs were examined after a mean observation period of 53.4 +/- 13 months. Eleven patients with 17 FPDs were lost to follow-up. After the 3-year recall visit, 7 FPDs in 7 patients were replaced because they were not clinically acceptable due to biologic or technical complications. After 5 years of clinical observation, 12 FPDs in 12 patients had to be replaced. One 5-unit FPD fractured as a result of trauma after 38 months. The success rate of the zirconia frameworks was 97.8%; however, the survival rate was 73.9% due to other complications. Secondary caries was found in 21.7% of the FPDs, and chipping of the veneering ceramic in 15.2%. There were no significant differences between the periodontal parameters of the test and control teeth.
Zirconia offers sufficient stability as a framework material for 3- and 4-unit posterior FPDs. The fit of the frameworks and veneering ceramics, however, should be improved.
IntroductionStatistical conceptsEstimating event probabilitiesRegression modelsRemarksReferences
Evidence is limited on the efficacy of zirconia-based fixed dental prostheses.
The purpose of this systemic review was to assess zirconia-based FDPs in terms of survival and complications.
Searches performed in PubMed databases were enriched by hand searches to identify suitable publications. The keywords used were: "zirconia" and "fixed dental prosthesis," "zirconia" and "crown," "zirconia" and "fixed partial denture" and "humans," "zirconia" and "crown" and "humans," "crown" and "all-ceramics," and "fixed partial denture" and "all-ceramics". Titles and abstracts were read to identify literature that fulfilled the inclusion criteria. Only peer reviewed clinical studies published in the English language from January 1999 through June 2011 were included.
Twelve clinical studies based on zirconia, framework design, and porcelain veneering technique met the inclusion criteria. Of the studies identified, 1 was a randomized clinical study with 3-year follow-up results; the others were cohort prospective studies. Clinical complications included chipping of veneering porcelain, abutment failure, and framework fracture. One study investigated pressed ceramics as the veneering material and found no chipping of veneering porcelain after 3 years.
Short term clinical data suggest that zirconia-based fixed dental prostheses may serve as an alternative to metal ceramic fixed dental prostheses in the anterior and posterior dentition.
The purpose of this prospective clinical study was to determine the success rate of single-unit posterior fixed dental prostheses (FDPs) with zirconia copings generated with two CAD/CAM systems, compared to porcelain-fused-to-metal (PFM) single-unit posterior FDPs after 5 years of function.
From 2005 to 2006, 60 patients who needed a single-unit FDP on a first molar in the mandibular jaw (left or right) in a private office setting were included in this study. The 60 first mandibular molars were randomly divided into three groups (n = 20): in the control group (group C), 20 PFM FDPs were included. In the other two groups CAD/CAM technology was used for the fabrication of the zirconium-oxide copings: 20 single-unit posterior FDPs with zirconia copings were generated with the Procera system (group P, Nobel Biocare); 20 single-unit posterior FDPs with zirconia copings were generated with the Lava system (group L, 3M ESPE). For the ANOVA follow-up data, the clinical life table method was applied. The statistical analysis was performed using two nonparametric tests, the log-rank test for k-groups and the Fisher exact test.
No statistically significant difference in the clinical outcome of zirconia-ceramic FDPs of both groups (P and L) evaluated together and metal-ceramic posterior single FDPs was found at 5 years of function; however, clinical data showed that technical problems, such as extended fracture of the veneering ceramic, tended to occur more frequently in the zirconia-ceramic FDP groups. The difference in the frequency of failure was statistically significant only in the comparison of groups C and P.
Even if no statistically significant difference in the clinical outcome of zirconia-ceramic FDPs of both groups (P and L) considered together and metal-ceramic posterior single FDPs was found at 5 years of function, clinical data showed that the two zirconia-ceramic FDP groups tended to have more frequent clinical problems: for this reason all the clinical and technical variables related to the use of zirconia-ceramic FDPs generated with CAD/CAM systems should be carefully considered prior to all treatment procedures.
This practice-based study evaluates the initial clinical performance of conventionally luted metal-ceramic and zirconia molar crowns fabricated with a prolonged cooling period of the veneering porcelain. Forty-nine patients were treated (group A: high precious alloy + low fusing porcelain; group B: zirconia crowns). All zirconia crowns were veneered with a modified porcelain firing cycle including a 6-minute cooling period. Ninety-two restorations (74 vital abutments/18 nonvital abutments) were evaluated after a mean observation period of 18.2 +/- 4.6 months. No complete failures or loss of vitality were recorded in either group. Two events were recorded in group A (1 loss of retention/1 minor ceramic chipping < 2 mm2). The third event occurred in group B (minor ceramic chipping <2 mm2). All ceramic defects could be polished intraorally. Statistical analysis revealed non-significant differences in success rates (p = 0.91) of metal-ceramic and zirconia crowns fabricated with a modified porcelain firing. The modified firing of the zirconia porcelain seems to decrease the risk for early ceramic chipping in the molar area, leading to a technical complication rate comparable to that of metal-ceramic crowns.
The aim of this prospective clinical study was to assess the long-term clinical survival rate and the technical and biological complication rates of zirconia-based posterior FDPs.
Forty-five patients in need of one or more posterior FDPs received 57 three- to five-unit zirconia-based FDPs. The frameworks were fabricated by means of a prototype computer-aided manufacturing (CAM) system (direct ceramic machining, DCM), first processing zirconia in the white stage. The frameworks were veneered with a prototype veneering ceramic.The FDPs were adhesively placed. At baseline, 6 months, and 1,2, 3, 5, 8 and 10 years of function, the FDPs were examined for technical and/or biological complications. Furthermore, the periodontal health of the abutment teeth (test) and untreated control teeth was analyzed. Statistical analysis was performed applying descriptive statistics, Kaplan-Meier survival and multiple mixed effects regression tests.
Twenty-one patients with 26 FDPs were examined at a mean observation time of 10.7 +/- 1.3 years. A total of 16 FDPs were lost to follow-up. Fifteen FDPs had to be replaced due to technical/biological complications; hence, the 10-year survival rate of the FDPs was 67%. Three framework fractures occurred, resulting in a 10-year survival rate for the zirconia frameworks of 91.5%. Chipping/fracture of the veneering ceramic was detected in 16 FDPs over 10 years (complication rate 32%). A significant correlation of the span of the FDPs and the incidence of chipping was observed: 4- and 5-unit FDPs had a 4.9 times higher probability for chipping than 3-unit FDPs. Marginal discrepancy/degradation was found in 90.7% of the FDPs over 10 years. At 11 of the FDPs (complication rate 27%), secondary caries occurred. No difference of the periodontal health was found around test and control teeth.
The zirconia frameworks exhibited very good long-term stability. However, the zirconia-based FDPs frequently exhibited problems such as marginal deficiency or chipping of the veneering ceramic. Both problems may be associated with the prototype status of the system.
This paper aimed to practice evidence-based dentistry by critically appraising relevant evidence to address a common question in prosthodontics. It sought to answer whether the survival and complication rates of all-ceramic fixed dental prostheses (FDPs) were comparable or superior to those of metal-ceramic FDPs, and to use this knowledge to guide clinical decisions.
A 6S search was conducted. No decision support systems or summaries were available. The journal Evidence-Based Dentistry (zero synopses), Trip database (three synopses, discarded), Cochrane database (three systematic reviews, discarded), MEDLINE OVID (six systematic reviews, one accepted), and Embase (zero systematic reviews) were searched. The selected systematic review assessed the survival and complication rates of all-ceramic and metal-ceramic FDPs. One additional prospective cohort study was considered relevant.
The systematic review addressed a well-focused clinical question, but its internal validity was compromised. The search was not systematic; inclusion methodology and impact of study characteristics on results were unclear. The external applicability was limited by compromised internal validity, broad outcome definitions, inaccurate results, and incomplete examination of stated aims. With care, however, the results could be applied to clinical practice. Estimated event rates and 5-year outcomes with a 95% confidence interval were calculated, with the survival rate of metal-ceramic FDPs significantly higher than that of all-ceramic FDPs. All-ceramic FDPs experienced a high incidence of technical failure. The prospective cohort addressed a well-focused clinical question with good internal validity. It compared outcomes of metal-ceramic FDPs provided before and after the introduction of implant therapy. Patient cohorts were clearly defined, similar at baseline, and treated equally. Ten-year Kaplan-Meier cumulative survival with standard errors was reported. Metal-ceramic FDP survival rates were high and significantly improved since the introduction of implants and the decreased use of structurally compromised abutments.
The results of the systematic review and prospective cohort were complementary: Metal-ceramic FDPs had high survival, with a significantly greater 5-year survival rate than all-ceramic FDPs. Differences in complications were unknown, but evidence indicated that the complication incidence of metal-ceramic FDPs was lower than that of all-ceramic FDPs. This evidence was directly applicable to the clinical scenario and will help guide clinical decision making.
The occurrence of "chipping" of all-ceramic restorations with Y-TZP frameworks has resulted in various designs and cooling procedures recommended for reducing such behavior. In this paper the temperature gradients during fast and slow cooling for conventional and anatomical designs are compared as well as an optical procedure to directly compare the influence of cooling rate on residual stress.
This investigation quantifies the temperature gradients between the inner and outer surfaces of crowns measured with thermocouples during two different cooling methods with uniform and anatomical frameworks. In the first method the crown was removed from the furnace after commencement of cooling whereas for the second method the crown was cooled to the glass transition temperature (600°C) before removal. Direct observation of the residual stresses was made with an optical polarimeter and thin slices of veneered copings.
This study observed that slow cooling decreases the temperature differences but still differences of up to 88°C were observed. For the fast cooled crown, temperature differences of more than 100°C for the uniform and 140°C for the anatomical framework at temperatures above the glass transition temperature were recorded. Optical polarimeter observations indicated much lower stresses within the porcelain layer upon cooling by removing the crown below the glass transition temperature.
Slow cooling during the final veneering of dental restorations with zirconia frameworks reduces the temperature gradients and residual stresses within the porcelain layer, which represent one possible cause for chipping. An anatomical designed framework did not show the same reduction extent.
Purpose:
The aim of this clinical retrospective study was to evaluate the survival and success rates of metal-ceramic fixed partial dentures (FPDs) made by dental students over an 18-year interval. Biologic and technical complications as well as patient satisfaction were recorded.
Materials and methods:
Fifty-seven patients with 82 FPDs from an original group of 104 patients with 128 FPDs attended an approximate clinical 18-year follow-up examination. The mean follow-up period was 17.7 years (range: 17.1 to 21.3 years).
Results:
Nine FPDs were lost because of extraction of an abutment tooth, and 1 FPD was removed for esthetic reasons. Technical problems recorded included loss of cementation, fractures in the metal framework, and need for placement of a dowel in an abutment tooth. The most common clinical findings were gingival bleeding on probing and appearance of supragingival crown margins. The survival rate of the FPDs was 78%, and the established success rate was 71%.
Conclusion:
This 18-year follow-up of metal-ceramic FPDs in just over half of the originally treated patient group was associated with good patient satisfaction and few biologic and technical complications. Int J Prosthodont 2011;24:314-319.
Ceramics have a long history in fixed prosthodontics of achieving optimal esthetics. Yttrium tetragonal zirconia polycrystal (Y-TZP)-based systems are a recent addition to the high-strength, all-ceramic systems used for crowns and fixed partial dentures. CAD/CAM-produced, Y-TZP-based systems are in considerable demand in esthetic and stress-bearing regions. The highly esthetic nature of zirconia coupled with its superior physical properties and biocompatibility have resulted in restorative systems that meet the demands of today's patients. Undoubtedly, these systems are considered to be prospective replacements for metal-ceramic restorations. This article reviews relevant contemporary literature regarding all-ceramic materials and systems and discusses their material properties, biocompatibility, advances in cementation, and more with special emphasis on clinical survival. The article also aims to provide recommendations for their use.
The authors conducted a randomized controlled clinical trial to determine whether performance differed between metal, zirconia and alumina fixed partial denture (FPD) frameworks veneered with pressed or layered ceramics designed for each framework type.
Posterior three-unit FPDs (N = 293) of 10 different framework/veneer ceramic combinations were placed by 115 dentists in 259 patients from their practices according to a masked protocol. Yearly, the clinicians graded the prostheses and the opposing dentition in vivo according to 17 criteria, and two independent scientists graded them in vitro by using gold-sputtered dies, scanning electron micrographs and clinical photographs.
Three metal and five zirconia frameworks tested were not statistically different, with zero and two fractures, respectively. Alumina frameworks were statistically worse, with 11 fractures. The veneer ceramics CZR Press (Noritake Dental, Aichi, Japan) and Pulse interface (Jensen Dental, North Haven, Conn.) performed best with zirconia and metal frameworks, respectively. Four nonleucite-containing veneer ceramics used with zirconia frameworks had substantially more fractures.
Five zirconia framework brands performed equally well and were statistically comparable with metal frameworks at three years. Two leucite-containing veneer ceramics applied by means of pressing techniques had the statistically lowest number of fractures.
Dentists can use metal or zirconia frameworks successfully if they are designed properly, but to avoid veneer ceramic surface crumbling and minimize chipping, use of leucite-containing pressed ceramics is indicated.
Schley J-S, Heussen N, Reich S, Fischer J, Haselhuhn K, Wolfart S. Survival probability of zirconia-based fixed dental prostheses up to 5 yr: a systematic review of the literature. Eur J Oral Sci 2010; 118: 443–450. © 2010 Eur J Oral Sci
The purpose of this systematic review was to calculate the 5-yr survival rates of all-ceramic zirconia-based fixed dental prostheses (FDPs) and to analyze technical and biological complications. An electronic literature search of MEDLINE (PubMed) was conducted independently by three reviewers to identify clinical studies from 1999 to 2009 and was completed by a manual search. Keywords and inclusion and exclusion criteria were well-defined. The search revealed 399 titles and led to the final analysis of 18 full-text articles. Nine studies met the inclusion criteria. Extracted data were statistically calculated into 5-yr survival rates and 5-yr complication-free rates by using Poisson regression analysis. In total, 310, 3- to 4-unit FDPs and 20 FDPs with more than 4 units were included. The estimated 5-yr survival rate for all FDPs was 94.29% (95% CI: 58.98–99.32); 19 FDPs were lost as a result of catastrophic failures. The 5-yr complication-free rate regarding technical complications was 76.41% (95% CI: 42.42–91.60) with chipping being the most frequent complication. Regarding biological complications, the 5-yr complication-free rate was 91.72% (95% CI: 59.19–98.53). The survival rates of zirconia-based short-unit FDPs are promising. However, an important improvement of the veneering systems is required, and for FDPs with more units in function, further randomized, controlled clinical trials are necessary.
The mechanical properties of veneering material in all-ceramic restorations are inferior to those of high-strength ceramics. The objective of this study was to assess the effect of three different firing protocols (different cooling times) on cohesive failure of veneered all-ceramic crowns using a newly developed in vitro test design.
A prepared anterior maxillary incisor was used to produce geometrically identical crowns (n=68) with a zirconia framework 0.4mm thick veneered with two different ceramics and prepared by use of three different firing protocols. Twenty crowns were loaded until fracture without artificial ageing; the other crowns underwent thermocycling and chewing simulation before ultimate-load testing. Statistical analysis was performed using non-parametric tests.
The results showed that a reduced temperature decrease after firing led to better performance of all-ceramic anterior crowns in the in vitro tests. A significant difference with regard to firing protocol (p=0.006) was observed for one veneering ceramic material only, however.
It can therefore be concluded that the test design presented enabled sensitive measurement of the effect of firing protocol on cohesive failure of all-ceramic crowns. The modified firing protocol with 6min additional cooling time resulted in greater resistance.
Zirconia is unique in its polymorphic crystalline makeup, reported to be sensitive to manufacturing and handling processes, and there is debate about which processing method is least harmful to the final product. Currently, zirconia restorations are manufactured by either soft or hard-milling processes, with the manufacturer of each claiming advantages over the other. Chipping of the veneering porcelain is reported as a common problem and has been labelled as its main clinical setback. The objective of this systematic review is to report on the clinical success of zirconia-based restorations fabricated by both milling processes, in regard to framework fractures and veneering porcelain chipping. A comprehensive review of the literature was completed for in vivo trials on zirconia restorations in MEDLINE and PubMed between 1950 and 2009. A manual hand search of relevant dental journals was also completed. Seventeen clinical trials involving zirconia-based restorations were found, 13 were conducted on fixed partial dentures, two on single crowns and two on zirconia implant abutments, of which 11 were based on soft-milled zirconia and six on hard-milled zirconia. Chipping of the veneering porcelain was a common occurrence, and framework fracture was only observed in soft-milled zirconia. Based on the limited number of short-term in vivo studies, zirconia appears to be suitable for the fabrication of single crowns, and fixed partial dentures and implant abutments providing strict protocols during the manufacturing and delivery process are adhered to. Further long-term prospective studies are necessary to establish the best manufacturing process for zirconia-based restorations.
This study of 3-unit fixed partial dentures (FPDs) evaluated the long-term efficacy and determined the frequencies and causes of failures.
A total of 134 FPDs made in an undergraduate university clinic for 98 patients were evaluated over a 20-year period. All patients were offered a supportive maintenance program. Failures of the FPDs were divided into irreversible (loss of FPDs) or reversible (FPDs intact after conservative treatment) complications and into biologic and technical/patient-related failures.
The overall survival rate was 73.1% after 20 years. There was a statistically significant difference (P = .036) between the survival rates in the mandible for the vital group (96.3%) versus the root canal-treated group (69.3%). Comparing the survival rate in the vital group for the restorations in the maxilla (70.2%) versus the mandible (96.3%), a statistically significant difference (P = .045) was found. The survival rate after 20 years for the 3-unit FPDs (73.1%) was significantly different from that of the FPDs with more than 3 units (61.5%) (P = .026). The main reason for failure was caries (38.1%).
The survival of 3-unit FPDs over a 20-year period is favorable and should be compared with other single-tooth replacement treatment options. There is an indication that the occurrence of a reversible complication has a predictive value for an irreversible complication later on.
The objective of this systematic review was to assess and compare the 5- and 10-year survival of different types of tooth-supported and implant-supported fixed dental prosthesis (FDPs) and single crowns (SCs) and to describe the incidence of biological and technical complications.
Three electronic searches complemented by manual searching were conducted to identify prospective and retrospective cohort studies on FDPs and SCs with a mean follow-up time of at least 5 years. Patients had to have been examined clinically at the follow-up visit. Failure and complication rates were analyzed using random-effects Poisson's regression models to obtain summary estimates of 5- and 10-year survival proportions.
Meta-analysis of the included studies indicated an estimated 5-year survival of conventional tooth-supported FDPs of 93.8%, cantilever FDPs of 91.4%, solely implant-supported FDPs of 95.2%, combined tooth-implant-supported FDPs of 95.5% and implant-supported SCs of 94.5%. Moreover, after 10 years of function the estimated survival decreased to 89.2% for conventional FDPs, to 80.3% for cantilever FDPs, to 86.7% for implant-supported FDPs, to 77.8% for combined tooth-implant-supported FDPs and to 89.4% for implant-supported SCs. Despite high survival rates, 38.7% the patients with implant-supported FDPs had some complications after the 5-year observation period. This is compared with 15.7% for conventional FDPs and 20.6% for cantilever FDPs, respectively. For conventional tooth-supported FDPs, the most frequent complications were biological complications like caries and loss of pulp vitality. Compared with tooth-supported FDPs, the incidence of technical complications was significantly higher for the implant-supported reconstructions. The most frequent technical complications were fractures of the veneer material (ceramic fractures or chipping), abutment or screw loosening and loss of retention.
On the basis of the results of the present systematic review, planning of prosthetic rehabilitations should preferentially include conventional end abutment tooth-supported FDPs, solely implant-supported FDPs or implant-supported SCs. Only for reasons of anatomical structures or patient-centered preferences and as a second option should cantilever tooth-supported FDPs or FDPs supported by combination of implants and teeth be chosen.
The objective of this systematic review was to assess the 5-year survival rates and incidences of complications of all-ceramic fixed dental prostheses (FDPs) and to compare them with those of metal-ceramic FDPs.
An electronic MEDLINE and Dental Global Publication Research System search complemented by manual searching was conducted to identify prospective and retrospective cohort studies on all-ceramic and metal-ceramic reconstructions with a mean follow-up time of at least 3 years. Patients had to have been examined clinically at the follow-up visit. Assessment of the identified studies and data abstraction was performed independently by three reviewers. Failure rates were analyzed using standard and random-effects Poisson regression models to obtain summary estimates of 5-year survival proportions.
The search provided 3473 titles for single crowns and FDPs and resulted in 100 abstracts for all-ceramic FDPs. Full-text analysis was performed for 39 articles, resulting in nine studies of ceramic FDPs that met the inclusion criteria. The data on survival and complication rates of metal-ceramic FDPs were obtained from a previous systematic review of Tan et al. (2004) and the updated version from the same authors (Pjetursson et al. 2007). In Poisson regression meta-analysis, the 5-year survival of metal-ceramic FDPs was significantly (P<0.0001) higher with 94.4% [95 confidence interval (CI): 91.1-96.5%] than the survival of all-ceramic FDPs, being 88.6% (95 CI: 78.3-94.2%). The frequencies of material fractures (framework and veneering material) were significantly (P<0.0001) higher for all-ceramic FDPs (6.5% and 13.6%) compared with those of metal-ceramic FDPs (1.6% and 2.9%). Other technical complications like loss of retention and biological complications like caries and loss of pulp vitality were similar for the two types of reconstructions over the 5-year observation period.
Based on the present systematic review of all-ceramic FDPs, significantly lower survival rates at 5 years were seen compared with metal-ceramic FDPs. The most frequent reason for failure of FDPs made out of glass-ceramics or glass-infiltrated ceramics was fracture of the reconstruction (framework and veneering ceramic). However, when zirconia was used as framework material, the reasons for failure were primarily biological and technical complications other than framework fracture.
The objective of this report is to summarize the results on survival and complication rates of different designs of fixed dental prostheses (FDP) published in a series of systematic reviews. Moreover, the various parameters for survival and risk assessment are to be used in attempt to perform treatment planning on the basis of scientific evidence. Three electronic searches complemented by manual searching were conducted to identify prospective and retrospective cohort studies on FDP and implant-supported single crowns (SC) with a mean follow-up time of at least 5 years. Patients had to have been examined clinically at the follow-up visit. Failure and complication rates were analyzed using random-effects Poisson regression models to obtain summary estimates of 5- and 10-year survival proportions. Meta-analysis of the studies included indicated an estimated 5-year survival of conventional tooth-supported FDP of 93.8%, cantilever FDP of 91.4%, solely implant-supported FDP of 95.2%, combined tooth-implant-supported FDP of 95.5% and implant-supported SC of 94.5% as well as resin-bonded bridges 87.7%. Moreover, after 10 years of function the estimated survival decreased to 89.2% for conventional FDP, to 80.3% for cantilever FDP, to 86.7% for implant-supported FDP, to 77.8% for combined tooth-implant-supported FDP, to 89.4% for implant-supported SC and to 65% for resin-bonded bridges. When planning prosthetic rehabilitations, conventional end-abutment tooth-supported FDP, solely implant-supported FDP or implant-supported SC should be the first treatment option. Only as a second option, because of reasons such as financial aspects patient-centered preferences or anatomical structures cantilever tooth-supported FDP, combined tooth-implant-supported FDP or resin-bonded bridges should be chosen.
This study of short-span fixed dental prostheses (Ss-FDPs) versus long-span FDPs (Ls-FDPs) evaluated the long-term efficacy and determined the frequencies and causes of failures.
A total of 236 Ss-FDPs and 86 Ls-FDPs made in an undergraduate university clinic for 149 and 70 patients, respectively, were evaluated over a 20-year period. Kaplan-Meier analysis with a 95% confidence interval was used to estimate the survival probability. Failures of the FDPs were divided into irreversible (loss of FDPs or finish line involvement) or reversible (FDPs and abutments intact after conservative treatment) complications and into biologic and technical/patient-related failures.
The overall survival estimations for Ss-FDPs (70.8%; 95% Cl: 63%-79%) and Ls-FDPs (52.8%; 36%-70%) at year 20, were statistically significantly different (P = .030). There was no statistically significant difference (P = .126) for the survival estimations for Ss-FDPs (60.4%; 48%-73%) versus Ls-FDPs (59.0%; 44%-74%) at year 19 in the root-canal treated (RCT) group. For the Ss-FDPs group there was a statistically significant difference (P = .009) between the vital (82.4%; 73%-92%) and RCT (60.4%; 49%-73%) groups at year 20. The reason for failure in the Ss-FDP group was of biologic origin in 55.6% to 66.7% of cases, but for the Ls-FDP group the failures were of technical origin in 56.0% to 84.0% of cases.
The survival of Ss-FDPs and Ls-FDPs over a 20-year period was favorable. The overall survival estimation for Ss-FDPs was statistically significantly better than for Ls-FDPs at year 20. The use of an RCT abutment becomes more significant in fixed prosthetic restorations with 4 or more units. Occurrence of a previously reversible complication is a predictive factor for an irreversible complication later on. A reversible complication within the first 2 years for an Ss-FDP will lead to an irreversible complication.
Failure time analysis Statistical and Methodological Aspects of Oral Health Research
- Ta Gerds
- V Qvist
- Jr Strub
- Cb Pipper
- Th Scheike
- N Keiding
Gerds TA, Qvist V, Strub JR, Pipper CB, Scheike TH, Keiding
N. Failure time analysis. In: Lesaffre E, Feine J, LeRoux B
(eds). Statistical and Methodological Aspects of Oral Health
Research. West Sussex: John Wiley and Sons, 2009:259–278.
Statistical and Methodological Aspects of Oral Health Research
- T A Gerds
- V Qvist
- J R Strub
- C B Pipper
- T H Scheike
- N Keiding
Gerds TA, Qvist V, Strub JR, Pipper CB, Scheike TH, Keiding
N. Failure time analysis. In: Lesaffre E, Feine J, LeRoux B
(eds). Statistical and Methodological Aspects of Oral Health
Research. West Sussex: John Wiley and Sons, 2009:259-278.