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Dentomaxillofacial Radiology 03/2013; · 1.08 Impact Factor
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ABSTRACT: The purpose of this study was to investigate the effect of simultaneous bone-augmentation procedures, and their combination, on the survival of dental implants and on the incidence of complications.
Within a retrospective analysis, 958 implants placed in 404 patients (mean age 58.18) were selected from a prospective clinical study. In 304 cases of reduced bone width, bone spreading (n = 217) with hand osteotomes, or bone splitting (n = 15), or guided bone regeneration (n = 72) combined with autogenous bone grafts were also performed. Eighty-eight implants were placed in combination with simultaneous internal sinus floor elevation without using graft material. For 194 additional implants, several augmentation procedures were combined because of extensive bone deficits. Three-hundred and seventy-two conventionally placed implants served as controls. Implant failures and complications were recorded after a mean observation period of 2.1 years (maximum 6.9 years).
Seventeen failures and nine additional implant-related complications were observed. After 4 years, Kaplan-Meier curves revealed a probability of survival without complication of 97.5% for conventionally placed implants, and 95.8% for implants placed in combination with a single augmentation technique. If several augmentation techniques were combined, success decreased to 94.1%. Complication-free survival differences between combined augmentation techniques and conventionally placed implants were significant (P = 0.004). Age, gender, and location showed no effect on implant survival.
It can be concluded that simultaneous bone-augmentation techniques slightly reduce short-term prognosis for dental implants. This effect was more pronounced when advanced defects required the combination of several augmentation procedures.
Clinical Oral Implants Research 09/2011; 23(10):1232-7. · 2.51 Impact Factor
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ABSTRACT: Evaluation of the effect of different span length and preparation designs on the fracture load of tooth-implant-supported fixed dental prostheses (TIFDPs) manufactured from yttrium-stabilized zirconia frameworks.
Forty-eight TIFDPs were manufactured using a CAD/CAM system and veneered with a press ceramic. Rigidly mounted implants (SLA, diameter 4.1 mm, length 10 mm) in the molar region with a titanium abutment were embedded in PMMA bases pairwise with premolars. All premolars were covered with heat-shrink tubing to simulate physiological tooth mobility. Six different test groups were prepared (a) differing in the preparation design of the premolar (inlay [i]; crown [c]), (b) the material of the premolar (metal [m]; natural human [h]) and (c) the length of the TIFDPs (3-unit [3]; 4-unit [4]). All TIFDPs underwent thermomechanical loading (TCML) (10,000 × 6.5°/60°; 6 × 10(5) × 50 N). The load to fracture (N) was measured and fracture sites were evaluated macroscopically.
None of the restorations failed during TCML. The mean fracture loads (standard deviations) were 1,522 N (249) for the 3-unit, inlay-retained TIFDPs on a metal abutment tooth (3-im), 1,910 N (165) for the 3-cm group, 1,049 N (183) for group 4-im, 1,274 N (282) for group 4-cm, 1,229 N (174) for group 4-ih and 911 N (205) for group 4-ch. Initial damages within the veneering ceramic occurred before the final failure of the restoration. The corresponding loads were 24-52% lower than the fracture load values.
All restorations tested could withstand the mastication forces expected. Fracture-load values for 3- and 4-unit inlay-crown and crown-crown-retained TIFDPs should spur further clinical investigation.
Clinical Oral Implants Research 08/2011; 23(6):719-25. · 2.51 Impact Factor
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ABSTRACT: The objective of this retrospective study was to compare biological and technical complications of implant-supported and tooth-implant-supported double crown-retained dentures (DCRDs) with those of tooth-supported DCRDs. Sixty-three DCRDs were monitored. One study group included 16 prostheses with a combination of implants and natural teeth as double crowns (ti group), whereas in the second study group, 19 dentures were retained exclusively on implants (ii group); a third study group with 28 exclusively tooth-supported dentures served as controls (tt group). Tooth loss, implant failure, and technical complications (loss of retention of primary crown, abutment screw loosening, loss of facing, fracture of resin denture teeth and fracture of saddle resin) were analysed. During the observation period of 24 months, no implants or teeth were lost in the ti group and three technical complications were recorded. In the ii group, two implants were lost, two cases of peri-implantitis occurred and four technical complications were observed. In the tt group, two cases of tooth loss and seven technical complications were observed. At the time of the last examination, all prostheses of the ti group and the ii group were functional. Patients of these two study groups reported high satisfaction with both function and aesthetics with no significant difference between the two groups. Treatment with DCRDs showed comparable results in the three study groups. The 2-year results indicate that double crowns can be recommended for implant and combined tooth-implant-retained dentures.
Clinical Oral Investigations 07/2011; 16(4):1031-7. · 2.36 Impact Factor
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ABSTRACT: The use of dental implants may be limited by lack of sufficient bone. The effectiveness of the alveolar ridge bone-spreading technique in the maxilla was compared with the standard technique. Bone spreading is a technique in which hand osteotomes are used to progressively enlarge the remaining deficient edentulous ridge to enable placement of dental implants.
In the test group (bone spreading), 72 patients received 126 implants. Thirty-six patients with 63 implants placed with conventional implant preparation served as a control group. Measurements of outcome were implant failure and complications after therapy. Kaplan-Meier curves were used to depict time from implant placement to implant failure or complication.
Six complications were observed after placement of the implants (3 implant failures, peri-implant inflammation in 2 implants, and 1 exposure of rough implant surface). There was a trend toward more implant failures in the control group.
Results of the ridge-spreading technique seem to be similar to those of the standard technique. However, these results should be regarded with caution because of the small number of complications.
Journal of oral and maxillofacial surgery: official journal of the American Association of Oral and Maxillofacial Surgeons 06/2011; 69(10):2557-63. · 1.58 Impact Factor
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Marc Schmitter,
Glen H Johnson,
Clovis Faggion,
Christina Klose,
Gergo Mitov,
Frank P Nothdurft,
Peter R Pospiech,
Peter Rammelsberg,
Brigitte Ohlmann,
Stefanie Schwarz,
Thomas Stober,
Petra Schiller,
Maria Pritsch
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ABSTRACT: The purpose of this study is to compare success rates of dual-viscosity impressions for two types of mixing techniques of the polyether elastomeric impression material. Additionally, influencing parameters on the success rates should be evaluated. The expectation was that there would be no difference between the success rates for the two mixing techniques. Two centres enrolled 290 subjects (727 teeth) into the trial. Patients were randomized for the two types of mixing techniques. One step, dual-viscosity impressions were made with either statically mixed Impregum Soft tray material (SAM) or dynamically mixed Impregum Penta H DuoSoft (DMM). Low viscosity Impregum Garant L DuoSoft was used for both groups. Gingival displacement involved the use of two braided cords. Full-arch trays were used exclusively. Both critical defects and operator errors were assessed for the first impression taken by trained dentists. The primary outcome was impression success. For comparison of the two mixing techniques, the odds ratio for success and the corresponding one-sided 95% confidence interval was calculated by a logistic regression model. To account for the dependence between several teeth within one patient, the method of general estimating equations was used. The overall impression success rate was 35.4%. Both mixing techniques showed equal success rates indicated by an OR of 1.0 and a lower limit of the one-sided 95% confidence interval of 0.71. Using this result to develop the corresponding interval for the difference, it could be shown that the success rate using SAM was at most 8.2% lower than that when using DMM with a probability of 95%. Multivariate logistic regression analysis of other potential influencing factors showed position of finish line (p = 0.008, supra compared to mixed), blood coagulation disorder (p = 0.021) and the level of training of the clinician (student vs dentist, p=0.008) to have an independent influence on the success rate. Dynamic mechanical mixing and the new static mixing of polyether tray material showed nearly equal success rates in the study even though success rates were comparatively low (DMM, 35.3%; SAM, 35.4%).
Clinical Oral Investigations 05/2011; 16(3):951-60. · 2.36 Impact Factor
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ABSTRACT: There are numerous scientific articles of studies on the prevalence of disorders with non-standardised examination and diagnostic protocols. Because their quality is heterogeneous, a new instrument has been developed for the assessment of such studies. The new instrument is based mainly on statistical criteria. The points assigned for each of the main criteria according to the information gained from each paper are summed up to form a Total Quality Score (TQS). The interrater reliability of the instrument was tested by employing Kappa and Interrater Correlation Coefficient (ICC) statistics. The latter was assessed on the results of three independent investigators. The new quality instrument appeared to be easy to use, and the instructions were comprehensible. The ICC((2,1)) for the TQS ranged between 0.94 and 1.00 indicating almost perfect agreement between the investigators. The reliability of the new instrument enables its use for scientific review purposes. In this way, its validity will also be tested. The instrument could be adopted for assessment of scientific articles of studies on the prevalence of disorders in many, similar, scientific areas.
Clinical Oral Investigations 05/2011; 16(3):781-8. · 2.36 Impact Factor
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ABSTRACT: 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.
Journal of dentistry 12/2010; 38(12):987-94. · 2.00 Impact Factor
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ABSTRACT: To assess the effect of different thicknesses of porcelain at the gingival of pontics, on the fracture load of zirconia-based, all-ceramic fixed dental prostheses (FDPs), anchored by inlays.
Box inlay cavities were prepared on mandibular molars and premolars. 40 FDPs with yttrium-stabilized zirconia frameworks of identical dimensions were manufactured using a CAD/CAM system and veneered with a press ceramic. The FDPs, replacing a premolar and a molar, were divided into four groups. In Group FR, the framework was all around unveneered. The next three groups received a 1 mm ceramic veneer on the buccal, occlusal and lingual side, but differed in the thickness of the ceramic veneer in the gingival, tensile zone of the pontics. In Group B-0, the gingival veneering was 0 mm, in Group B 1 mm and in Group B-2, 2 mm of gingival porcelain. A group of inlay-retained metal-ceramic FDPs (mc) served as control. All FDPs were subjected to thermal cycling and 600,000 cycles of mechanical load of 50 N. The load to fracture (N) was measured and fracture sites were evaluated macroscopically. A single-factor Analysis of Variance was used to analyze the data.
None of the FDPs debonded after thermal cycling or mechanical loading and no signs of fractures or other defects were observed. The mean fracture loads and standard deviations in parentheses were: 647 N (123) for Group B-0, 716 N (102) for Group FR, 812 N (48) for Group B-1, 934 N (129) for Group B-2 and 1005 N (SD 81) for Group MC. Means for Groups B-0 and FR were not shown to differ, and the same for mean fracture strength of Groups B-2 and MC.
American journal of dentistry 06/2010; 23(3):147-51. · 0.76 Impact Factor
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ABSTRACT: The purpose of this study was to assess the prevalence of anxiety and depression in temporomandibular disorders (TMD) patient subgroups and in controls with or without chronic facial pain (CFP).
Our sample consisted of 61 men and 161 women. All TMD patients had suffered from pain for at least 6 months and were divided into two subgroups-an exclusively myofascial pain group and an exclusively joint pain group. Subjects without signs or symptoms of TMD but with and without CFP served as controls. All subjects were examined by calibrated examiners in accordance with the Research Diagnostic Criteria for Temporomandibular Disorders. The German version of the Hospital Anxiety and Depression Scale was used for assessment of anxiety and depression. Analysis of covariance was used to determine the effects of sex, age, and subgroup on anxiety and depression scores. Additional t-tests were performed and the subgroups were then compared with those from a general population sample.
Females from the exclusively myofascial pain group were significantly more depressed than those from the general population or from the exclusively joint pain group. Male controls with CFP were significantly more depressed than female CFP controls. For anxiety, no significant effect of sex or subgroup was found.
Depression may play an important role in women with chronic myofascial pain whereas anxiety does not seem to be relevant for either females or males. Further anxiety screening of patients with temporomandibular pain could not be justified.
Journal of dentistry 05/2010; 38(5):369-76. · 2.00 Impact Factor
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ABSTRACT: A newly formulated vinyl siloxanether elastomeric impression material is available, but there is little knowledge of its accuracy in relation to existing materials.
The purpose of this in vitro study was to assess the accuracy of disinfected vinyl siloxanether impressions and compare the accuracy to a common vinyl polysiloxane and a polyether impression system.
Impressions were made from a modified dentoform master model containing a simulated crown preparation. Dimensional changes (mm) between the master model and working casts (type IV gypsum) were assessed. The following were evaluated: vinyl polysiloxane in a 1-step, dual-viscosity technique (VPS Dual), polyether as monophase material (PE Mono), and vinyl siloxanether in a 1-step, dual-viscosity (VSE Dual), and monophase technique (VSE Mono). Measurements of the master model and working casts, including anteroposterior (AP) and cross-arch (XA) dimensions, were made with a measuring microscope. The simulated crown preparation was measured in mesiodistal (MDG, MDO), buccolingual (BLG, BLO), and occlusogingival dimensions (OGL, OGB). Disinfection involved immersion for 10 minutes in potassium peroxomonosulfate, sodium benzoate, tartaric acid solution, or no disinfection (control) (n=8). A multivariate GLM statistical approach (MANOVA) was used to analyze the data (alpha=.05). Pearson's correlation test was used for related dimensions.
The AP and XA dimensions of working casts were larger than the master for the disinfected condition and control. Whether disinfected or not, the working dies were shorter in height (OGB, OGL), larger in the buccolingual dimension (BLO, BLG), somewhat larger in the MDO dimension, and somewhat smaller in the MDG dimension compared to the prepared tooth of the master model, resulting in an irregular or oval profile. There were significant differences among the impression systems for each dimension except AP. Differences between the disinfected and nondisinfected conditions were significant (P=.03) with respect to dimensions of the gypsum working cast, but not for dimensions of the working die (P=.97). In general, differences relative to the master were small and of minor clinical significance considering marginal gaps of crowns smaller than 150-100 mum are considered clinically acceptable.
VSE monophase impressions and VSE dual-viscosity impressions demonstrated acceptable accuracy for clinical use with immersion disinfection, since the results for VSE were comparable to the results for PE and VPS materials, and the differences as compared to the master model were small.
The Journal of prosthetic dentistry 04/2010; 103(4):228-39. · 1.22 Impact Factor
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ABSTRACT: The purpose of this study was to evaluate the survival and success of early-loaded implants placed in the intraforaminal area of the edentulous mandible, and the survival of the implant-supported fixed dental prostheses (FDP).
Thirty-seven patients (18.9% male, mean age 64.5 years) with edentulous lower jaws were treated with implant-supported FDPs in the mandible. One hundred and eighty-five screw-type implants were placed in the intraforaminal area of the symphysis (five implants per patient). Immediately after implant placement, a framework was fabricated and the FDP was manufactured on the framework. Within 2 weeks, the implants were rigidly connected and loaded with the implant-retained FDP.
During the 1-8-year observation period (mean 4.5 years), a total of 32 implant-retained complications occurred. Nineteen implants were lost in 10 patients, resulting in a cumulative survival of 89.7%. Nine implants in five patients did not osseointegrate. Although these implants were not removed, because stability within the connective tissue was acceptable and inflammation was absent, they were recorded as unsuccessful. Consequently, the cumulative success declined to 84.9%. Four implants in three patients had clinical signs of periimplantitis (2.2% of all implants). Denture-related complications included one complete failure, when one FDP had to be removed after the last of five implants had been replaced. Furthermore, 10 fractures of the framework occurred in six patients, three FDPs had to be adapted or modified, and the facing of the FDP had to be repaired 16 times in 11 patients.
Although one-stage early-loaded implants functioned well for most patients with edentulous mandibles, immediate loading is associated with a larger number of implant-related complications than in other studies investigating delayed loading. Because of the substantial prosthetic complications and aftercare, this procedure cannot be generally recommended.
Clinical Oral Implants Research 03/2010; 21(3):284-9. · 2.51 Impact Factor
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ABSTRACT: The wear behavior of newly developed denture teeth with nanofillers may be different from teeth with other chemical formulations.
The purpose of this study was to examine the 3-body wear resistance of 11 different commercially available resin denture teeth.
The materials tested were conventional (SR Orthotyp PE, Orthognath) and cross-linked acrylic resin teeth without inorganic fillers (Premium 8, SR Postaris DCL, Trubyte Portrait, Artiplus), composite resin teeth with inorganic fillers (SR Orthosit PE, Vitapan), and composite resin teeth (experimental materials) with inorganic nanofillers (NC Veracia Posterior, e-Ha, Mondial). Human enamel and a ceramic denture tooth (Lumin Vacuum) were used as reference materials. The 3-body wear test was performed in a wear machine developed by the Academic Center for Dentistry Amsterdam (ACTA), with millet suspension acting as an abrasive medium (n=10, test load: 15 N, slip rate: 20%, number of cycles: 100,000). Wear was determined with the aid of a profilometer. Data were analyzed with the Kruskal-Wallis test and Mann-Whitney U test using the closed testing approach (significance level for familywise error rate, alpha=.05).
None of the acrylic and composite resin materials tested in this study demonstrated the 3-body wear resistance of ceramic teeth or human enamel. Teeth with inorganic fillers demonstrated significantly lower wear values than conventional or cross-linked acrylic resin teeth without fillers. Composite resin teeth with traditional fillers showed significantly lower wear than composite resin teeth with nanofillers.
Denture teeth with and without inorganic fillers differed significantly with regard to the degree of wear generated in the ACTA wear simulator. The incorporation of nanofillers did not improve the wear resistance compared to teeth with traditional fillers.
The Journal of prosthetic dentistry 02/2010; 103(2):108-17. · 1.22 Impact Factor
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ABSTRACT: To determine the prevalence of facial pain and temporomandibular disorders (TMD) in people located in urban and rural areas in a newly industrialized country (Iran).
Two-hundred twenty-three subjects between 18 and 65 years of age (mean: 32.07; SD: 10.83) were randomly selected from an urban area and a rural area. One-hundred nineteen subjects from Mashhad (major city) and 104 subjects from Zoshk (village) were voluntarily recruited from medical health-care centers. Subjects who consulted the health-care center for dental, ear, nose, or throat issues were excluded. The monitoring of public health attendance of all citizens at designated health-care centers is compulsory by local law. All subjects were examined in accordance with the Research Diagnostic Criteria for TMD (RDC/TMD). Facial pain was assessed by using a questionnaire; the prevalence of myofascial pain, disc displacement, and degenerative disorders was determined by clinical examination. Nonparametric tests were used to assess group differences (ie, between village and city).
Subjects in urban areas suffered less from facial pain (20.2% versus 46.2%; P < .01 [Mann-Whitney U test]) than subjects in rural areas. The frequency of TMD, disc displacement, and degenerative disorders was greater in the rural area.
The symptoms under investigation were significantly more widespread in rural than in urban areas. With regard to TMD per se, the place of residence appears to be unimportant. However, the rural population was significantly affected by facial pain.
Journal of orofacial pain 01/2010; 24(4):361-6. · 2.59 Impact Factor
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ABSTRACT: The main objective of this systematic review is to compare the effects of treatment of peri-implant infection between animal and human studies.
A literature search was conducted using the Medline, Cochrane Central Register of Controlled Trials, and Latin American and Caribbean Health Sciences Literature databases up to and including May 2008. In addition, bibliographies of systematic reviews on peri-implant diseases were searched manually. Non-surgical and surgical treatments of peri-implantitis/mucositis in animal models or human studies were compared. Meta-analysis was conducted to investigate the difference between the reported treatment effects in animal and human studies. Changes in probing pocket depth (PPD) and probing attachment level (PAL) from baseline measurements were used as measures of outcome. Single-level and multilevel meta-regression analysis was performed by taking into account the different follow-up times of the studies included.
The single-level and multilevel random-effects meta-analysis showed that the difference in PPD reduction [0.31 mm, 95% confidence interval (CI): -0.27, 0.88] and in PAL gain (0.21 mm, 95% CI: -0.47, 0.88) between animal and human studies was not statistically significant. The random-effects meta-regression suggested that studies with longer follow-up times revealed greater PPD reduction (0.25 mm per month, 95% CI: 0.14, 0.35). However, when the different follow-up times were taken into account, these differences became greater. Substantial heterogeneity between studies was found in the meta-analyses (I(2)=97.6% for animal studies and 99.9% for human studies).
There was great heterogeneity between human and animal studies in terms of study designs and treatment procedures. Therefore, the results from this meta-analysis should be interpreted with caution. Heterogeneity between studies and its causes merit further investigations.
Clinical Oral Implants Research 11/2009; 21(2):137-47. · 2.51 Impact Factor
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ABSTRACT: Although myofascial pain has often been described as being associated with psychosocial stress, detailed evidence in support of this assumption, either from standardized clinical examination or from validated chronic stress questionnaires, is absent. The hypothesis of the present study was that some stressors lead to higher scores in patients suffering from chronic myofascial pain than in pain-free controls and in patients suffering from chronic facial pain. One hundred and fifty subjects were included in the study, and depending on clinical findings, divided into three groups: exclusively chronic myofascial pain group, controls with chronic facial pain but without temporomandibular disorders (TMD), and controls without pain or TMD. Chronic stress was assessed on nine subscales by use of a validated questionnaire. Myofascial pain patients have a significantly higher stress score for "social isolation" than pain-free controls (t-test, p = 0.003). However, they do not have higher scores than patients suffering from facial pain (t test, p = 0.169). Thus, the hypothesis of this study could not be completely rejected.
Clinical Oral Investigations 09/2009; 14(5):593-7. · 2.36 Impact Factor
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ABSTRACT: Animal research is conducted to understand the causes and treatments of human diseases. Clinical human studies may not, however, be able to replicate results previously obtained from animal experiments.
to assess whether or not peri-implantitis therapies conducted in animal experiments were successfully replicated in human clinical trials.
Dental journals classified by citation impact factor were searched in the Journal Citation Reports database for animal trials on treatment of peri-implantitis between 1992 and 2008. It was assumed that prominent findings from high-ranked journals would be more likely to be tested in subsequent human clinical trials. A second literature search was conducted in the Pubmed, Cochrane, and Lilacs databases to identify potential human studies that repeated or replicated animal experiments. Controlled trials and case-series were included in the analysis. Because of the heterogeneity of the studies (e.g., different study designs and different outcome measures), only descriptive analysis was undertaken.
Of 1199 studies retrieved, 53 (23 animal and 30 human studies) were selected for the review. Because no animal experiment and human trial had comparable study procedures, precise determination of the success of replication from animal experiments in clinical trials was not possible. Overall, the study characteristics were extremely heterogeneous.
To reduce the great heterogeneity between animal and human studies on peri-implantitis, researchers should pay attention to standardization of research procedures. Power analysis and sample-size calculation in animal experiments and human trials should be always considered when planning a research study.
Journal of dentistry 07/2009; 37(10):737-47. · 2.00 Impact Factor
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ABSTRACT: Investigation of the short-term survival of implants placed in combination with an internal sinus lift (ISL) without graft material.
Thirty-six patients received 92 screw-shaped dental implants in combination with an ISL. No bone grafts or bone substitutes were used. Forty-four patients with 77 implants in the native posterior maxilla served as controls. X-rays taken after implant placement and 6 months later were evaluated for the presence of bone gain at the apical aspect of the implants. Kaplan-Meier survival curves and Cox regression analysis were used to estimate survival curves and to isolate risk factors for implant failures.
Within a mean observation period of 1.2 years (minimum 9 months; maximum 3.7 years), four failures were recorded in the experimental group and two in the controls. The probability of survival was above 94% for both groups. Six-nine months after surgery, bone gain was observed in 29 out of 92 implants. Comparison of the experimental group and controls revealed no effect of ISL and membrane perforation on the probability of survival.
Promising short-term outcomes were observed for implants with ISL without graft material; for a substantial proportion of implants, apical bone gain was observed in the first 6-9 months.
Journal Of Clinical Periodontology 03/2009; 36(2):177-83. · 3.00 Impact Factor
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ABSTRACT: Evaluation of the fracture resistance of all-ceramic cantilever fixed dental prostheses (FDPs) manufactured from zirconia frameworks and veneered with a press ceramic.
Two mandibular premolars were prepared either with a box inlay cavity or with a full crown chamfer preparation and then duplicated. 40-three-unit cantilever FDPs replacing one premolar, with a group size of eight for each design, were manufactured. In group i-i the cantilever FDPs were retained by two inlays, in group i-c by an inlay-crown combination, and in group c-c by two crowns. The frameworks in groups i-c-R and c-c-R were reinforced by an additional shoulder on the oral side of the zirconia frameworks. All FDPs were subjected to thermal cycling (TC) and 600,000 cycles of mechanical loading (ML) with 50 N. The load to fracture was measured and fracture sites were evaluated.
The mean fracture values ranged from 172 N to 792 N. Fracture-strength values were significantly lower for the i-i retained FDPs than for the i-c and c-c combinations. There was no significant effect of the reinforcing shoulder in groups i-c-R and c-c-R. For FDPs with a crown on the terminal tooth, fractures were usually within the distal wall of the distal crown.
Inlay-inlay retained cantilever FDPs cannot withstand the mastication forces expected. Fracture load values for inlay-crown and crown-crown-retained FDPs encourage further clinical investigation. The mode of fracture indicates that reinforcement of the distal crown wall might enhance fracture resistance.
Acta odontologica Scandinavica 09/2008; 66(4):200-6. · 1.41 Impact Factor
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ABSTRACT: The objective of this study was to evaluate the clinical performance of zirconia-based all-ceramic fixed partial dentures anchored by inlays.
A total of thirty FPDs, manufactured using a zirconia frame and veneered with press ceramic, were anchored by use of inlay retainers. All FPDs were designed to replace one missing molar and were adhesively luted by use of one of two different resin cements. Documentation included failures and other complications, plaque accumulation, and aesthetic and functional performance. Statistical analysis was performed using a cox-regression model.
During the 12 months observation period a total of thirteen clinically relevant complications occurred-four delaminations of the veneer and six decementations. Three FPDs had to be replaced because of a fracture of the framework. The cement chosen, the location, and the design of the retainer had no statistically significant effect on the occurrence of complications. During the observation period, accumulation of plaque on the abutment teeth was not significantly greater than on reference teeth. Postoperative sensitivity did not differ significantly between the different luting cement groups. The aesthetic and functional performance of the FPDs was acceptable.
Improved adhesion between resin cement and inlay retainer is desirable before general recommendation of all-ceramic inlay-retained FPDs. Use of different luting cements seems to have no effect on the occurrence of complications.
Journal of Dentistry 07/2008; 36(9):692-6. · 2.95 Impact Factor
