Article

Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: Marginal and internal fit

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Abstract

Statement of problem: Trials comparing the overall performances of digital and conventional workflows in restorative dentistry are lacking. Purpose: The purpose of the third part of this clinical study was to test whether the fit of zirconia 3-unit frameworks for fixed partial dentures fabricated with fully digital workflows differed from that of metal frameworks fabricated with the conventional workflow. Material and methods: In each of 10 participants, 4 fixed-partial-denture frameworks were fabricated for the same abutment teeth according to a randomly generated sequence. Digital workflows were applied for the fabrication of 3 zirconia frameworks with Lava, iTero, and Cerec infiniDent systems. The conventional workflow included a polyether impression, manual waxing, the lost-wax technique, and the casting of a metal framework. The discrepancies between the frameworks and the abutment teeth were registered using the replica technique with polyvinyl siloxane. The dimensions of the marginal discrepancy (Discrepancymarginal) and the internal discrepancy in 4 different regions of interest (Discrepancyshoulder, Discrepancyaxial, Discrepancycusp, and Discrepancyocclusal) were assessed using a light microscope. Post hoc t tests with Bonferroni correction were applied to detect differences (α=.05). Results: Discrepancyshoulder was 96.1 ±61.7 μm for the iTero, 106.9 ±96.0 μm for the Lava, 112.2 ±76.7 μm for the Cerec infiniDent, and 126.5 ±91.0 μm for the conventional workflow. The difference between the iTero and the conventional workflow was statistically significant (P=.029). Discrepancyocclusal was 153.5 ±66.8 μm for the iTero, 203.3 ±127.9 μm for the Lava, 179.7 ±63.1 μm for the Cerec infiniDent, and 148.8 ±66.8 μm for the conventional workflow. Discrepancyocclusal was significantly lower for the conventional workflow than for the Lava and the Cerec infindent workflows (P<.01). The iTero resulted in significantly lower values of Discrepancyocclusal than the Lava and the Cerec infiniDent workflows (P<.01). Conclusions: In terms of framework fit in the region of the shoulder, digitally fabricated zirconia 3-unit frameworks presented similar or better fit than the conventionally fabricated metal frameworks. In the occlusal regions, the conventionally fabricated metal frameworks achieved a more favorable fit than the CAD-CAM zirconia frameworks.

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... Two studies, Gjelvold et al. 11 and Zeltner et al. 12 reported results on tooth-supported single crowns. Meanwhile, Benic et al. 13 reported results on fixed dental prostheses. Ahberg et al. 14 reported results for both tooth-supported single crowns and fixed dental prostheses. ...
... Quality and risk bias assessment of the randomized controlled trials are summarized in Fig. 2. The Cochrane Collaboration tool showed an overall low risk of bias in all the included studies. Gjelvold et al. 11 , Zeltner et al. 12 , Benic et al. 13 and Cappare et al. 14 did not report sufficient information on allocation concealment. Benic et al. 15 reported a high risk of confounding bias and the risk was minimized by selecting a study design with intrasubject comparison. ...
... Four studies (Gjelvold et al. 11 , Zeltner et al. 12 , Benic et al. 13 , and Ahberg et al. 14 ) on digitally fabricated tooth-supported fixed prosthesis had focused on other clinical outcomes which were marginal fit, internal fit, interproximal contact points, and occlusal contacts. The types of tooth-supported fixed prostheses fabricated in these studies vary, from single crowns to fixed dental prostheses (bridge) up to six units. ...
Article
Objective: To analyze the clinical outcomes of implant-supported prostheses and tooth-supported fixed prostheses, fabricated from digital and conventional impression. Materials and methods: The literature search was carried out on two electronic databases (PubMed and Cochrane Library). Randomized controlled trials (RCT) published from January 2011 to September 2022 were included. The bias risk was evaluated using Cochrane Risk of Bias Tool 2.0. Further screening was done for meta-analysis according to modified Newcastle-Ottawa scoring criteria. Forest plot was generated using a statistical method of inverse variance of random effect with 95% confidence interval. Results: A total of 8 randomized controlled trials were included for systematic review out of which four studies were based on tooth-supported fixed prosthesis and remaining four were based on implant-supported prosthesis. Further screening was conducted and three studies were eligible for meta-analysis. Tooth-supported fixed prosthesis fabricated from digital impression showed no significant difference in the marginal fit in any region measured, except for occlusal region where conventional impression showed more favorable marginal fit. Implant-supported prosthesis fabricated from digital impression showed survival rates ranging from 97.3 to 100% and there was no statistically significant difference in marginal bone loss (p = 0.14). Conclusion: Implant-supported prostheses fabricated from digital and conventional impressions show no significant differences in their clinical outcomes. Tooth-supported fixed prostheses fabricated from digital impression have shown favorable findings in terms of marginal fit. Despite that, there is still lack of clinical trials with larger sample size and longer follow-up periods. Future studies that fulfill these two criteria are deemed necessary.
... The occlusal reduction was 2 mm, and the axial reduction was 1.5 mm. 25 The finishing line located at the juxta-gingival level was a 1-mm-wide fillet. On each model, a DS and a CI were taken by a single operator (O.N.B.). ...
... The choice of these sites was based on previous studies. 25,[29][30][31] For the marginal fit, S1 corresponds to the distance between the cervical margin and the FDP margin mesially, S2 distally, S3 on the vestibular side, and S4 on the palatal side. With respect to the internal space, three sites-E1/E5/E1*/E5*; E2/E4/E2*/E4*; and E3/E3*were selected to determine the thickness between the prosthetic abutment and the underside of the FDP at the midaxial, (E1/E5/E1*/E5*), axio-occlusal (E2/E4/E2*/E4*), and centro-occlusal (E3/E3*) sites (Fig 2f,g). ...
... 32,39 The results of the present study TA B L E 1 Mean measurement values and standard deviations (SD) in micrometers (µm) for marginal and internal fit in two study groups: digital scans (DSs) and conventional impressions (CIs) corroborate those of previous studies that reported that DS provides better marginal and internal fit than CI for fabricating zirconia single crowns or FDPs. 11,15,23,25,[40][41][42][43][44] In the literature, there was a lack of scientific data on the accuracy of DSs for long-span reconstructions, especially as Kim and Kim argued in their investigation that the length of the edentulous area can influence the extent of the marginal and internal gap with the use of direct or indirect digitalization. 45 Recently, Uluc et al compared the marginal and internal fit of 60 five-unit monolithic zirconia-based FDPs fabricated with CAD-CAM technology using direct and indirect digitalization methods. ...
Article
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Purpose: This study aimed to compare the marginal and internal fit of five-unit zirconia fixed dental prostheses fabricated using digital scans and conventional impressions. Materials and methods: Nine master models with three zirconia abutments were scanned with an intraoral scanner (test group), and nine conventional impressions (control group) of these same models were also made. The stone casts from theses impressions were scanned with a laboratory extraoral scanner (D700, 3Shape, Copenhagen, Denmark). A total of 18 five-unit zirconia fixed dental prostheses frameworks (test group, n = 9; control group, n = 9) were manufactured. Marginal and internal fit (in μm) were evaluated using the replica method under micro-computed tomography. Analysis of variance (one-way ANOVA) and Kruskal Wallis tests were used to compare continuous variables across two groups. A level of P <0.05 was accepted as statistically significant. Results: The mean ±standard deviation of the marginal fit was 95.03 ±12.74 μm in the test group and 106.02 ±14.51 μm in the control group. The lowest marginal mean value was observed in the test group, with a statistically significant difference comparing to the control group (F = 14. 56, P <0.05). The mean ±standard deviation of the internal fit was 103.61 ±9.32 μm and 106.38 ±7.64 μm, respectively, in the test and control groups, with no statistically significant difference (F = 1.56, P >0.05). The mean values of both groups were clinically acceptable. Conclusions: The five-unit zirconia fixed dental prostheses fabricated with digital scans showed better fit than conventional impressions group. Within the limitations of this study, these results are encouraging and continued progress in the digital field should allow for more accurate long-span restorations. This article is protected by copyright. All rights reserved.
... Berrendero et al. 2016 [21] Pradíes et al. 2015 [25] Rödiger et al. 2017 [22] Sakornwimon et al. 2017 [23] Syrek et al. 2010 [26] Zarauz et al. 2016 [27] Boeddinghaus et al. 2015 [24] Bosniac et al. 2019 [28] Haddadi et al. 2019 [36] Zeltner et al. 2017 [37] Koulivand et al. 2020 [42] Yun et al. 2017 [43] Benic et al. 2019 [12] Low risk of bias The results obtained by systematic analysis of the selected articles can be categorized into three groups based on the restorative material of the final restoration (Table 2). Specifically, zirconia-, lithium disilicate-, and PFM/alloy-based restorations were investigated in terms of marginal discrepancy after digital vs. conventional impression making. ...
... Specifically, zirconia-, lithium disilicate-, and PFM/alloy-based restorations were investigated in terms of marginal discrepancy after digital vs. conventional impression making. In five of the selected articles, the investigators included protocols that tested more than one restorative material, that is, zirconia, lithium disilicate, or alloys [9][10][11][12][13]. ...
... Moreover, Dahl et al. [13] found insignificant differences in the internal fit of 3-unit FDPs digitally fabricated from different materials: pre-sintered zirconium dioxide, hot isostatically pressed zirconium dioxide, lithium disilicate glass ceramic, milled cobalt-chromium, and lasersintered cobalt-chromium. Finally, Benic et al. [12] reported that digitally fabricated zirconia 3-unit frameworks present similar or better fit than conventionally fabricated metal frameworks. The conventionally fabricated metal frameworks achieved a more favorable fit in the occlusal regions than the CAD-CAM zirconia restorations. ...
Article
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Advances of digital technology are rapidly adopted in dental practice. This systematic review aimed to collect evidence on the accuracy of fit of different types of fixed dental prostheses (FDPs) fabricated through digital, conventional, or combination impression techniques. Data collection was based on the guidelines of the preferred reporting items for systematic reviews and meta-analyses (PRISMA). Two databases (PubMed, Scopus) were searched for articles in English published between 2010 and 2021 resulting in 480 articles. Of those, 35 studies fulfilled the inclusion criteria. These articles referred to three groups of materials/techniques including all-ceramic (zirconia; lithium disilicate) and porcelain-fused-to-metal (PFM) restorations. Results showed clinically acceptable marginal fit (< 120 μm) for all materials and impression techniques. Α fully digital workflow appears more promising for the construction of short-span zirconia FDPs. Nevertheless, most articles evaluated marginal/internal fit of single crowns or short-span FDPs in vitro, while clinical data are limited for long-span FDPs. The necessity for gingival retraction remains a major drawback of all impression techniques, increasing procedural time and patient discomfort. Besides, factors related to the fabrication process, including milling and 3D printing of working models significantly influence the outcome. Overall, there still some way to go before digital technology can be incorporated in complex treatment plans in prosthodontics.
... 34 Marginal and internal fit are affected by the fabrication technique as well as the impression technique. 35 For both impression techniques, the same zirconia material and the same milling technique were used, by designing them in their own design programs 36 without changing the scanner's data into special formats, in order to avoid any bias in the production process and avoid data loss. 12 Debate continues as to whether restorations produced by intraoral scanning provide a precision of fit comparable or even superior to restorations produced with laboratory scanners. ...
... 12 Debate continues as to whether restorations produced by intraoral scanning provide a precision of fit comparable or even superior to restorations produced with laboratory scanners. 26,27,36,37 Regarding the marginal fit of restorations created by CAD-CAM based on intraoral scanning, some in vitro studies have shown marginal adaptation better than restorations produced with laboratory scanners. 26,27,37,38 This is supported by the findings of Berrendero et al.'s clinical study. ...
... 39 In contrast, there are in vitro studies that did not show significant differences in marginal accuracy when comparing intraoral scanner and laboratory scanner restoration groups. 20,28,36,40 A clinical study comparing three different intraoral scanning devices showed significant differences in marginal and internal fit among the three intraoral scanner systems tested, thus revealing a significant effect of the intraoral scanner system used. 41 Su and Sun 27 evaluated the compatibility of 3-unit zirconia frameworks produced by intraoral and laboratory scanners. ...
Article
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Purpose: This study aimed to compare the marginal and internal fit of 3-unit monolithic zirconia restorations that were designed by using the data obtained with the aid of intraoral and laboratory scanners. Materials and methods: For the fabrication of 3-unit monolithic zirconia restorations using impressions taken from the maxillary master cast, plaster cast was created and scanned in laboratory scanners (InEos X5 and D900L). The main cast was also scanned with different intraoral scanners (Omnicam [OMNI], Primescan [PS], Trios 3 [T3], Trios 4 [T4]) (n = 12 per group). Zirconia fixed partial dentures were virtually designed, produced from presintered block, and subsequently sintered. Marginal and internal discrepancy values (in µm) were measured by using silicone replica method under stereomicroscope. Data were statistically analyzed by using 1-way ANOVA and Kruskal Wallis tests (P<.05). Results: In terms of marginal adaptation, the measurements on the canine tooth indicated better performance with intraoral scanners than those in laboratory scanners, but there was no difference among intraoral scanners (P<.05). In the premolar tooth, PS had the lowest marginal (86.9 ± 19.2 µm) and axial (92.4 ± 14.8 µm), and T4 had the lowest axio-occlusal (89.4 ± 15.6 µm) and occlusal (89.1 ± 13.9 µm) discrepancy value. In both canine and premolar teeth, the D900L was found to be the most marginally and internally inconsistent scanner. Conclusion: Within the limits of the study, marginal and internal discrepancy values were generally lower in intraoral scanners than in laboratory scanners. Marginal discrepancy values of scanners were clinically acceptable (< 120 µm), except D900L.
... Besides reducing the laboratory workload, the advances when effectively utilized have made it easier for us to preserve the marginal integrity of our restorations and have brought us closer to visualizing the subgingival domain that we would only have to judge or imagine. 2,3,28 The first step in the fabrication of the prosthesis requires a good focus on tooth preparation but an immense focus on making an accurate impression. The negative replica sent by the clinician is the only reference used in the laboratory for the fabrication of the prosthesis. ...
... 37 As per the observations of the clinical trial conducted by Benic et al, 3 unit fixed prosthesis made using zirconia showed a better fit when they made fabricated using a digital workflow which also consisted of CAD-CAM technology for fabricating the prosthesis in the marginal areas, while conventional workflows showed better results in the occlusal adaptation. 28 It was also stated that metal-ceramic prosthesis tended to show higher discrepancies than a ceramic prosthesis. 28,38 He also stated that a majority of discrepancies are noticed with respect to casted restorations which may add to the fact that they are mostly fabricated as metalceramic restorations. ...
... 28 It was also stated that metal-ceramic prosthesis tended to show higher discrepancies than a ceramic prosthesis. 28,38 He also stated that a majority of discrepancies are noticed with respect to casted restorations which may add to the fact that they are mostly fabricated as metalceramic restorations. 28 Benic et al also put forth the opinion that poor occlusal fit that was observed for prosthesis fabricated using zirconia ceramics, could be compensated for by the superior qualities of the material. ...
Article
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In today's world there is an ever increasing focus on providing a patient with the most aesthetic restorations and prosthesis. To achieve such perfection most dentists rely heavily on a subgingival margin which often leads to biologic width violation due to marginal inaccuracy of the restoration. This violation of the attachment apparatus results in inflammation and dysregulation of the immune pathways, which lead to initiation of bone loss. The end stage of this violation is, initiation of the pathology of chronic periodontitis. The use of a digital workflow can help in increasing the marginal adaptation of the prosthesis hence reducing the iatrogenic biologic width violations while maintaining the aesthetic demands of the patients and providing more reliable results. Digital impressions can help in reducing the finish line errors both in the clinics and the laboratories. Hence by avoiding biologic width violation we can help in maintenance of the periodontal hygiene of the patient.
... Previous studies have compared the accuracy of conventional and digital impressions based on the fit of the final restorations. Digital impression displayed comparable or higher accuracy than conventional for single-unit restorations and FPDs up to 4 units [7][8][9]. In addition, various studies demonstrated the high variability in trueness and precision according to the impression method used [10][11][12]. ...
... Informed consent was obtained from all patients. The minimal sample size was calculated based on similar studies [9,11] to detect a standardized effect size of 1.245 change in the primary outcome, as statistically significant with 90% power and at a significance level of 95% (accepted alpha error of 0.05). Twelve patients were included in the study, aged between 18 and 45 years with a missing upper first premolar, good oral hygiene, and with no need for additional extended treatment as endodontic and orthodontic treatment. ...
... Twelve patients were included in the study, aged between 18 and 45 years with a missing upper first premolar, good oral hygiene, and with no need for additional extended treatment as endodontic and orthodontic treatment. Patients with bad oral hygiene, advanced periodontitis, subgingival restorations or root caries, short abutments, obvious malalignment, or parafunctional habits were excluded [9]. ...
Article
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Objectives This study aimed to compare the accuracy of conventional and digital impressions based on the fit of produced three-unit fixed partial dentures (FPDs) in vivo and the trueness and precision of both impression techniques. Materials and methods Twelve patients received a conventional polyether impression (group C, control, n=12) and a digital impression with CS3500 (group D, test, n=12) for each participant. Monolithic multilayer zirconia FPDs were fabricated, and the internal and marginal fit were assessed using the replica technique. Trueness and precision of both impression methods were assessed in vitro. A master model was used to create a reference scan. The master model received conventional impressions (group C, control, n=5) and digital impressions (group D, test, n=5). The virtual models of both groups were superimposed over the reference scan (5 superimpositions) using a three-dimensional (3D) processing software, and the 3D deviations were measured and averaged to obtain trueness value. For precision, the virtual models of each group were superimposed over each other (10 superimpositions) and the average deviation value was calculated. The data were analyzed using one-tailed Mann–Whitney U test at P ≤ 0.05. Results Group D resulted in a significantly better marginal and internal fit (30.91±15.15 and 30.86±13.57 μm for group D and 40.02±19.50 and 41.86±18.94 μm for group C). The mean values of trueness and precision for conventional and digital techniques were comparable (trueness: 62.8±5.45 and 62.72±12.01 μm and precision: 56.47±27 and 60.9±14.5 μm, respectively). Conclusions No significant difference was found between conventional and digital impressions in 3D datasets accuracy. In addition, both techniques resulted in FPDs with an acceptable clinical fit. However, the FPDs fabricated using the digital technique displayed better internal and marginal fit. Clinical relevance The applied impression technique as well as the computer-aided processing of the produced virtual models can significantly affect the fit of the final restoration. Direct digital impression is recommended over conventional impression for fabricating accurate monolithic zirconia 3-unit FPDs. Trial registration This clinical trial was retrospectively registered on August 11, 2020, in the Pan African Clinical Trial Registry database, and the number for the registry is PACTR202008685699453.
... 2,5,6 The scientific literature has investigated the accuracy of IOS and the data emerging from these studies are reassuring: the errors are minimal and compatible with the design and fabrication of single crowns (SCS) 7-9 and fixed partial prostheses (FPPs). [10][11][12] However, the literature still does not support the use of direct intraoral scanning for the design and fabrication of fixed full arches (FFAs) supported by 6 or more implants. 13,14 Research focused on this topic has revealed that the intrinsic error of IOSs can be a problem when scanning the complete arch. ...
... 8,9 In CAD, the first step consists of replacing the MEs of the SBs with the corresponding LF, linked to the implant library components (i.e., different gluing bases available with the implant system, on which the technician can model a screwed superstructure or individual abutments). 8, [10][11][12]25 The replacement of the ME is a geometric approximation of the scanned object, and the corresponding LF is key. 9, 10,25 The CAD software superimposes the LF on the ME, using a best-fit algorithm; therefore the LF is integrated into the master model, and the technician can proceed with the modeling. ...
... 5,6 For all these reasons, several studies have investigated the process of intraoral scanning, to identify the problems related to the process and improve its accuracy. 2,4,[9][10][11][12] This investigation is necessary to overcome the current limitations and to extend the application of direct intraoral scanning from the design and fabrication of short-span restorations (SCs 7-9 and FPPs 10-12 ) to long-span restorations (FFAs). [13][14][15][16] Most of the studies, however, have focused their attention on the IOSs, [9][10][11][12][13][14][15][16] and only a few scientific papers have investigated the influence of the other elements involved in the intraoral scanning process: the operator, 18 the patient, 19 the environment, 20 and the SB or the digital transfer. ...
Article
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Purpose: To investigate and compare the production tolerances of six different commercially available implant scan bodies (SBs), with the null hypothesis that there would be no tolerances in the production or significant differences between the different SBs. Materials and methods: Six different implant SBs (IO 6A-B and IO 2B-B, Nobel Biocare; RC 4.1 mm 025.4915 and RN 4.8 mm 048.168, Straumann; KR 352KR1A0, BTK BIOTEC; and AANISR4013T, MegaGen) were evaluated. Five specimens of each SB type (a total of 30 samples) were screwed onto the corresponding implant analogs and underwent dimensional analysis with optical microscopy (QVI Smartscope Flash 200, Optical Gaging Products) and precision probing (R 0.25, Renishaw). The outcome variables were SB height, diameter, and angle of the flat face on the top (plane). All measurements were compared with the corresponding computer-assisted design library measurements used as a reference to assess the manufacturing tolerances. Statistical analyses were performed to compare the results obtained with the different SBs. Results: Tolerances in the manufacture of the SBs were reported in height, diameter, and plane measurements, and statistically significant differences between the different types of SBs were found. Therefore, the null hypothesis was rejected. Most of the deviations and tolerances were reported in height measurements with conical connection implants. Conclusions: Tolerances in the production and statistically significant differences were found among the six commercially available SBs evaluated in this study. Additional studies with larger sample sizes and other types of SBs are needed.
... Schaefer et al, 19 Almeida e Silva et al, 20 Alfaro et al, 21 Solaberrieta et al, 22 Afify et al 23 In vitro study Sailer et al, 25 Benic et al 26 Double publication by same authors ...
... Ultimately, only 14 randomized controlled crossover studies or parallel groups and 2 prospective comparative studies were included. 25,26,[32][33][34][35][36][37][38][39][40][41][42][43][44][45] The bibliographic research flow chart is presented in Figure 1, and the characteristics of the included studies, the main parameters, and the results of the 16 articles are shown in Table 2. ...
... The PICO 3 question (marginal fit) was evaluated in 13 articles that measured the perpendicular distance from the internal surface at the margin of the restoration to the preparation finish line through the silicone replica technique or a 150-mm-diameter explorer. 26,32,33,[35][36][37][38][39][40][41][42][43]45 To observe the gaps between the prosthesis and the tooth margin, 5 studies used a light microscope, 26,36,37,40,41 7 used a stereomicroscope, 26,32,35,39,42,43,45 1 used a macroscope, 33 and 1 used an explorer. 38 The average marginal fit values were lower for digital scanning techniques (80.9 ±31.9 mm) than for conventional impressions (92.1 ±35.4 mm), but the difference was not statistically significant (P>.05) ( Table 5). ...
Article
Statement of problem Intraoral scanners have significantly improved over the last decade. Nevertheless, data comparing intraoral digital scans with conventional impressions are sparse. Purpose The purpose of this systematic review and meta-analysis was to determine the impact of impression technique (digital scans versus conventional impressions) on the clinical time, patient comfort, and marginal fit of tooth-supported prostheses. Material and methods The authors conducted a literature search based on the Population, Intervention, Comparison, and Outcome (PICO) framework in 3 databases to identify clinical trials with no language or date restrictions. The mean clinical time, patient comfort, and marginal fit values of each study were independently extracted by 2 review authors and categorized according to the scanning or impression method. The authors assessed the study-level risk of bias. Results A total of 16 clinical studies met the inclusion criteria. The mean clinical time was statistically similar for digital scan procedures (784 ±252 seconds) and for conventional impression methods (1125 ±159 seconds) (P>.05). The digital scan techniques were more comfortable for patients than conventional impressions; the mean visual analog scale score was 67.8 ±21.7 for digital scans and 39.6 ±9.3 for conventional impressions (P<.05). The mean marginal fit was 80.9 ±31.9 μm and 92.1 ±35.4 μm for digital scan and conventional impressions, respectively, with no statistically significant difference (P>.05). Conclusions Digital scan techniques are comparable with conventional impressions in terms of clinical time and marginal fit but are more comfortable for patients than conventional impression techniques.
... To date, in fixed implant prosthodontics, the scientific literature has validated the use of IOSs for capturing optical impressions for the design and manufacture of shortspan restorations such as single crowns (SCs) [7][8][9][10] and partial prostheses (PPs) [11][12][13]. However, in the case of long-span restorations, and in particular for full arches (FAs), IOSs do not yet seem to be sufficiently accurate, as reported by several studies [14,15] and reviews of the literature [16,17]. ...
... In metrics, accuracy is "the closeness of agreement between a measured quantity value and a true quantity value of a measurand" (JCGM 200:2012; ISO 5725- 1,1994) [2,4,13], and when it comes to IOSs, it is the combination of trueness and precision. Trueness is the most important factor, defined as "the closeness of agreement between the arithmetic mean of a large number of test results and the true or accepted reference value". ...
... Trueness expresses how much the average of a series of measurements approaches reality; a measurement is truer the closer it is to the actual value of the object. To evaluate the trueness of a measurement requires a reference: in the case of dental models, this is an acquisition made with a machine with certified accuracy (possibly ≤5 μm), such as a coordinate measuring machine (CMM), or an industrial optical or desktop scanner [2,4,13]. Specifically, the acquisitions obtained with IOSs must be compared with those obtained with one of these reference machines to be mathematically validated. ...
Article
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Background: The literature has not yet validated the use of intraoral scanners (IOSs) for full-arch (FA) implant impression. Hence, the aim of this in vitro study was to assess and compare the trueness of 12 different IOSs in FA implant impression. Methods: A stone-cast model of a totally edentulous maxilla with 6 implant analogues and scanbodies (SBs) was scanned with a desktop scanner (Freedom UHD®) to capture a reference model (RM), and with 12 IOSs (ITERO ELEMENTS 5D®; PRIMESCAN® and OMNICAM®; CS 3700® and CS 3600®; TRIOS3®; i-500®; EMERALD S® and EMERALD®; VIRTUO VIVO® and DWIO®; RUNEYES QUICKSCAN®). Ten scans were taken using each IOS, and each was compared to the RM, to evaluate trueness. A mesh/mesh method and a nurbs/nurbs method were used to evaluate the overall trueness of the scans; linear and cross distances between the SBs were used to evaluate the local trueness of the scans. The analysis was performed using reverse engineering software (Studio®, Geomagics; Magics®, Materialise). A statistical evaluation was performed. Results: With the mesh/mesh method, the best results were obtained by CS 3700® (mean error 30.4 μm) followed by ITERO ELEMENTS 5D® (31.4 μm), i-500® (32.2 μm), TRIOS 3® (36.4 μm), CS 3600® (36.5 μm), PRIMESCAN® (38.4 μm), VIRTUO VIVO® (43.8 μm), RUNEYES® (44.4 μm), EMERALD S® (52.9 μm), EMERALD® (76.1 μm), OMNICAM® (79.6 μm) and DWIO® (98.4 μm). With the nurbs/nurbs method, the best results were obtained by ITERO ELEMENTS 5D® (mean error 16.1 μm), followed by PRIMESCAN® (19.3 μm), TRIOS 3® (20.2 μm), i-500® (20.8 μm), CS 3700® (21.9 μm), CS 3600® (24.4 μm), VIRTUO VIVO® (32.0 μm), RUNEYES® (33.9 μm), EMERALD S® (36.8 μm), OMNICAM® (47.0 μm), EMERALD® (51.9 μm) and DWIO® (69.9 μm). Statistically significant differences were found between the IOSs. Linear and cross distances between the SBs (local trueness analysis) confirmed the data that emerged from the overall trueness evaluation. Conclusions: Different levels of trueness were found among the IOSs evaluated in this study. Further studies are needed to confirm these results.
... In the prosthetic field, the digital revolution has a strong impact because the dentist can capture optical impressions with IOS [2,3,[11][12][13]; these impressions are used by the dental technician for the planning and hence the production of a whole series of fixed prosthetic restorations (inlays [12,16], onlays [16], single crowns [17,18], and bridges of up to 4 or 5 elements [19]). The literature now shows that all these applications are possible and represent a clinical reality [11]. ...
... Although IOSs are becoming widespread and have become a very useful tool for capturing impressions in partially edentulous patients [2,[11][12][13][14][15][16][17][18][19], the scientific literature does not seem to support their use in completely edentulous patients [22][23][24]. Numerous systematic reviews suggest that IOSs do not yet have adequate accuracy to allow CAD and thus the fabrication of full-arch-type restorations [22][23][24], particularly in patients with implants [23,24]; in this, the distance between the implants seems to play a major role [25]. ...
... The use of IOS for capturing optical impressions on natural teeth and on implants is rapidly spreading in dental offices [11][12][13][16][17][18][19]. ...
Article
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Purpose: To present a digital method that combines intraoral and face scanning for the computer-assisted design/computer-assisted manufacturing (CAD/CAM) fabrication of implant-supported bars for maxillary overdentures. Methods: Over a 2-year period, all patients presenting to a private dental clinic with a removable complete denture in the maxilla, seeking rehabilitation with implants, were considered for inclusion in this study. Inclusion criteria were fully edentulous maxilla, functional problems with the preexisting denture, opposing dentition, and sufficient bone volume to insert four implants. Exclusion criteria were age < 55 years, need for bone augmentation, uncompensated diabetes mellitus, immunocompromised status, radio- and/or chemotherapy, and previous treatment with oral and/or intravenous aminobisphosphonates. All patients were rehabilitated with a maxillary overdenture supported by a CAD/CAM polyether-ether-ketone (PEEK) implant-supported bar. The outcomes of the study were the passive fit/adaptation of the bar, the 1-year implant survival, and the success rates of the implant-supported overdentures. Results: 15 patients (6 males, 9 females; mean age 68.8 ± 4.7 years) received 60 implants and were rehabilitated with a maxillary overdenture supported by a PEEK bar, designed and milled from an intraoral digital impression. The intraoral scans were integrated with face scans, in order to design each bar with all available patient data (soft tissues, prosthesis, implants, and face) in the correct spatial position. When testing the 3D-printed resin bar, 12 bars out of 15 (80%) had a perfect passive adaptation and fit; in contrast, 3 out of 15 (20%) did not have a sufficient passive fit or adaptation. No implants were lost, for a 1-year survival of 100% (60/60 surviving implants). However, some complications (two fixtures with peri-implantitis in the same patient and two repaired overdentures in two different patients) occurred. This determined a 1-year success rate of 80% for the implant-supported overdenture. Conclusions: In this study, the combination of intraoral and face scans allowed to successfully restore fully edentulous patients with maxillary overdentures supported by 4 implants and a CAD/CAM PEEK bar. Further studies are needed to confirm these outcomes.
... Intraoral scanning (IOS) of teeth has become a routine procedure in clinical practice. Compared to conventional impression-making, the accuracy, efficiency, and patient-reported outcomes of IOS are similar, if not better [4,5]. In the digital workflow, one or more buccal scans are captured to relate the maxillary and mandibular digital scans to their correct maxillomandibular relationship. ...
... This limitation may undermine the actual clinical utility of the AI system. Such a source of error could be eliminated by collecting in vivo intra-oral scans for training instead of scanning stone casts [4]. ...
Article
Full-text available
Purpose: Artificial intelligence (AI) may be used to learn and predict the maxillomandibular relationship, particularly when the number of occluding teeth pairs is insufficient. This study aimed to investigate the feasibility of training a new two-stage coarse-to-fine teeth alignment pipeline AI system in predicting maxillomandibular relationships based on the occlusal morphology of antagonistic teeth. Methods: Maxillary and mandibular stone casts were collected and scanned at the maximal intercuspal position (MIP). A deep learning alignment network was trained using 90% of cast pairs. The remaining 10% of pairs were input into the trained AI system for validation. The maxillomandibular relationships predicted by the AI system were superimposed and compared with those of the mounted casts. Cartesian x-, y-, and z-coordinates were defined for each mandibular tooth scan with respect to (w.r.t.) its occlusal plane and dental midline. The discrepancy in the position of maxillary teeth scans was described based on rotation and translation. Results: A total of 325 pairs of maxillary and mandibular stone casts were collected, with 300 pairs used for training and 25 for validation. For the AI-predicted maxillomandibular relationship, the mean rotational discrepancies w.r.t. the x-, y-, and z-axis were 1.407°±1.548°, 1.269°±8.476°, and 0.730°±1.334°, respectively. The mean translational discrepancies w.r.t. the x-, y-, and z-axis were 0.185±1.324 mm, 1.222±0.848 mm, -1.034±0.273 mm, respectively. Conclusions: The AI-predicted maxillomandibular relationship for maxillary and mandibular teeth scans shows discrepancies of less than 1.3 mm and 1.5° compared to the actual relationships.
... Of the 459 retrieved titles, 318 abstracts were selected; subsequently, 20 articles were chosen for the full-text review ( Table 2). Of the remaining 20 articles, 9 papers were excluded as they had an in vitro design [17][18][19][20][21][22][23][24][25], 5 articles were excluded since they assessed only single-unit restorations [26][27][28][29][30], and one study investigated digital and conventional workflows on natural teeth [31]. All clinical studies evaluated mixed workflows for the fabrication of implant-supported partial dentures and no study compared full digital and conventional workflows [32][33][34][35][36] leaving no study for the final analysis ( Figure 1). ...
... Mello et al. [23] compared the digital and conventional workflows for the resin casts for fabrication of digital and conventional frameworks, and then compared the framework fit. Benic et al, [31] clinically compared full digital and conventional workflows. There were 10 participants, each with 4 fixed partial denture frameworks fabricated for the same abutment teeth through the digital and conventional methods. ...
Article
Full-text available
Objectives: This study aimed to do a comprehensive systematic review on the comparison of digital and conventional workflows regarding prosthetic outcomes, accuracy of implant impressions, framework passivity and fit, and clinical fabrication of multi-unit implant-supported fixed restorations. Materials and Methods: The EMBASE, PubMed, Scopus, and Cochrane Library databases were searched for relevant articles published up until April 2020. Results: No in-vivo article was found to compare full digital and conventional workflows regarding the accuracy of implant impressions, passivity and fit of frameworks, and prosthetic outcomes. There was no study to investigate full digital and conventional workflows for clinical fabrication of multi-unit implant-supported fixed restorations. Conclusion: This empty review highlights the need for further research to compare full digital and conventional workflows for implant-supported restorations.
... Accurate adjustment of the cement space is therefore, of paramount importance. In previous studies the cement gap for a single computer-aided design (CAD) and computer-aided manufacturing (CAM) crown was set within a broad range of µm [3,14,15,[18][19][20][21]. The cement gap for digitally created fixed partial prostheses with a maximum of five units was set between 30 and 60 µm [22][23][24][25][26]. Determining the optimal spacing is further complicated by the intricate settings in the software, including the cement gap, the margin ramp (the distance from the preparation margin where the cement gap is not applied, and the additional space (an extra gap including the marginal ramp zone). ...
... The marginal and internal gap of a single 3D-printed resin crown deteriorated upon increasing the cement gap from 70 µm to 100 µm [32]. Previous studies [22][23][24][25][26] recorded a 35-80 µm marginal gap following 30-70 µm cement spacing at fixed prosthesis fabricated from zirconia, which correlated with the marginal gap measured for Emerald S in this study (66 µm). Nevertheless, 70 µm is recommended as the minimum cement space to let the cement distribute evenly and freely and minimize the restoration elevation [33]. ...
Article
Full-text available
Objectives: To validate the virtual-fit alignment, analyze the impact of cement spacing on internal/marginal gaps, and correlate results with conventional trueness measures. Methods: Four dental abutment models were scanned using an industrial reference scanner (one time each), Emerald S (three times each), and Medit i700 (three times each) intraoral scanners (IOS). On each IOS scan (n = 24), three complete-arch fixed frameworks were designed with 70 or 140 µm cement space with no marginal space (groups 70 and 140) and 70 µm with an additional 20 µm space, including the margin (group 70+20). Two types of alignment were performed by GOM Inspect software. The reference and IOS scans were aligned through a conventional iterative closest point algorithm (ICP) where the penetration of the two scans was permitted into each other (conventional trueness method). Second, the computer-aided designs were superimposed with the reference scan also using an ICP, but preventing the design from virtual penetration into the model (virtual-fit method). The virtual-fit algorithm was validated by non-penetration alignment of the designs with the IOS scans. Internal and marginal gap was measured between the design and the abutments. The difference between spacing groups was compared by Friedman's test. A statistical correlation (Spearman's Rho Test) was computed between the measured gaps and the conventional trueness method. A significant difference was accepted at p<0.05 after the Bonferroni correction. Results: The gaps deviated from the set cement space by 3-13 µm on IOS scans (validation of virtual-fit algorithm). The internal gap of the design on the reference scan was not affected by cement spacing (Emerald S, p = 0.779; Medit i700, p = 0.205). The marginal gap in groups 70 and 70+20 was significantly lower than in group 140 in Emerald S (p<0.05). In Medit i700, it was lower in the 70+20 group than in the group 70 (p<0.01) and in the group 140 (p<0.05). Some Medit i700 scans exhibited high marginal gaps within group 70 but not in groups 70 and 140. The measured gaps correlated significantly (r = 0.51-0.81, p<0.05-0.001) with the conventional trueness but were 2.6-4.6 times higher (p<0.001). Conclusion: Virtual-fit alignment can simulate restoration seating. A 20 µm marginal and 90 µm internal spacing could compensate for scan errors up to several hundred micrometers. However, 140 µm internal spacing is counterproductive. The conventional trueness method could only partially predict framework misfit. Clinical significance: The virtual-fit method can provide clinically interpretable data for intraoral scanners. Emerald S and Medit i700 intraoral scanners are suitable for fabricating complete-arch fixed tooth-supported prostheses. In addition, a slight elevation of spacing at the margin could compensate for moderate inaccuracies in a scan.
... Existe mucha discrepancia en los resultados obtenidos por los diferentes autores, incluso al evaluar las justifi caciones de los resultados, eligen interpretarlos de diferentes maneras, enfatizando variables que no se repiten entre investigadores. Por otro lado, Min-Kyung et al., compararon el ajuste marginal del disilicato de litio, zirconia monolítica opaca y translúcida; encontrando un mejor ajuste para el disilicato de litio seguido de la zirconia translúcida, además de concluir que el ajuste marginal no estaba en relación al tipo de terminación (15); pero en otro estudio con una metología similar, encontraron que si bien no existía diferencia signifi cativa en el desajuste marginal y oclusal, sí se observaban menores desajustes axiales cuando se usaban técnicas digitales de impresión (8,16,17), en este punto se puede evidenciar que si bien los ajustes marginales están, en su mayoría dentro de los aceptables clínicamente, aún se continúa con la búsqueda de disminuir más estos valores con la fi nalidad, quizá de obtener una pasividad real entra la restauración y el sustrato, aunque otras variables también entran a tallar en este punto. ...
... Si evaluamos a las coronas monolíticas en relación al desgaste (término para describir la pérdida progresiva de la superfi cie de un diente debido a varios factores, excepto la caries dental) (16), que pueden ocasionar a las estructuras antagonistas, encontramos estudios con diversos resultados y conclusiones divergentes por la suma de variables consideradas, básicamente algunos mencionan que va a depender de la metodología del estudio (in vitro/in vivo) (12,18), otros el tipo de antagonista a utilizarse (esmalte, hidroxiapatita reforzada, acero inoxidable, resina acrílica, cerámica, etc.) (9,17), pero al parecer convergen en el punto de que la restauración va a ocasionar mayor desgaste que un antagonista natural (13,16). ...
Article
Full-text available
Objetivo : Identificar las publicaciones recientes de los materiales de restauración a base de dióxido de zirconio que incluyan estudios clínicos, propiedades mecánicas, físicas y estéticas, así como su evolución, manufactura y diversas aplicaciones en la práctica clínica diaria. Material y métodos : La búsqueda sistemática de la literatura se realizará en las bases de datos de PubMed y Ebsco, se considerarán publicaciones del 2010- 2019 y que fueran investigaciones clínicas, laboratoriales y todas aquellas que mostraban la evolución en el tiempo del dióxido de zirconio, así como su aplicabilidad y diversificación. Resultados: Se revisaron 48 artículos que cumplieron con los criterios de selección para la revisión bibliográfica. Se encontró que todas las restauraciones protésicas a base de dióxido de zirconio, indistintamente a su forma de utilización, mostraron un desempeño clínico muy similar a los tres años, después de ese tiempo, dependerá del tipo de utilización, composición y elección del caso. Conclusiones: El éxito clínico de las restauraciones en base a dióxido de zirconio, es debido a las múltiples ventajas mecánicas y, con las recientes modificaciones estructurales, sumadas al agregado de aditivos para su estabilización, se perfila como un material idóneo para el trabajo tanto en zonas estéticas como en áreas de necesidad de soporte mecánico con carga funcional elevada.
... For example, Matt et al. (2015) found that more than half of the companies that adopted digital transformation strategies were worse than before the transformation, and some companies may still face bankruptcy risks. Benic et al. (2019) found that although the expected performance of some companies has increased, 60%-85% of organizations failed in their plans. The real challenge in the digital transformation process is not to keep up with all technological changes, but rather to make companies more flexible and cost-effective through the use of digital technology, thereby minimizing risks. ...
Article
The retail industry is at the forefront and epitome of China's rapid digitalization process. However, the digital transformation process of retail enterprises has not been smooth sailing, and some even lamented that "transformation is death, and non-transformation is waiting for death." In the era of the digital economy, how to improve the digital resilience of enterprises has become an important topic in enterprise management practice and theoretical research. This paper uses A-share listed retail companies in Shanghai and Shenzhen Stock Exchanges in China from 2012 to 2021 as samples and uses Stata17 software to conduct an empirical test on the relationship between "digital transformation of retail enterprises" and digital resilience. The empirical results show that the digital transformation of Chinese retail enterprises has a significant positive effect on digital resilience. This significant promotion effect still holds after a series of endogeneity and robustness tests. This study helps to enrich the connotation of digital resilience, enrich the existing measurement of digital resilience, and expand the research on the effects and results of digital transformation in Chinese retail enterprises.
... R ehabilitating patients who wear removable dentures, especially elderly patients, involves a strong focus on enhancing quality of life by restoring function and esthetics. 1 It is thought that trauma, periodontal disease, and decay all play a role in teeth loss. 2 Fixed partial restorations, 3,4 removable partial dentures, 5,6 and implant-supported prostheses 2,7e9 are all options for replacing missing teeth. Preserving the last few teeth and related components is more crucial in any prosthetic rehabilitation than storing what is lost. ...
... It was proven that the internal fit of the restorations obtained through digital impressions is slightly worse than those obtained from conventional impressions but without clinical significance [17]. A ceramic 3unit framework digitally performed will fit better than a metallic 3-unit framework fabricated by conventional technology [18]. ...
... 2e10,13 A randomized clinical trial by Cheng et al. demonstrated that digital workflow for fabrication of provisional crowns represented an alternative option to shorten the working time with better crown accuracy of fit when compared to the conventional technique with direct provisionalization, especially for clinicians with less clinical experience. 22 The crown made by complete digital workflow had clinically acceptable results in marginal fit, internal fit, and occlusion, 9,17,18,20 it even had better interproximal contact than the conventional one. 17 In the present study, the technicians and the clinicians who performed the accuracy assessment were both blinded to the original information of the tested SCs in order to improve the evidence of the comparative result. ...
Article
Full-text available
Background/Purpose The digital impression is a promising technique in prosthodontic treatment. However, the influencing factors of patient comfort is lacking, and the evidence of crown quality is mostly based on in vitro studies. The purpose of this double-blinded clinical trial was to compare the patient satisfaction and crown accuracy of two different intraoral scanners (IOSs) for the fabrication of all-ceramic single crowns (SCs). Materials and methods Participants in need of posterior tooth-supported SCs were enrolled. Each patient received quadrant scan by both the Metal Industries Research and Development Centre (MIRDC) IOS and Carestream CS3500 in a random sequence. After scanning, participants had to fill in a 6-item perception questionnaire that based on 5-point Likert scale for two IOSs. Both data were sent to a dental laboratory to fabricate the monolithic lithium disilicate SCs. The crown accuracy including marginal fit, proximal contact, occlusal contact, and general satisfaction were accessed based on 5-point scale. Results A total of 15 participants with 40 crowns (20 SCs in each group) were investigated. Regarding to patient satisfaction, there was no statistically significant difference in total score between MIRDC and Carestream IOSs (23.6 ± 3.79 vs 23.1 ± 4.28, P = 0.36). In terms of crown accuracy, there was significantly different in total score and all the evaluated parameters between MIRDC and Carestream groups (6.1 ± 1.41 vs 13.3 ± 3.75, P < 0.001). Conclusion Both MIRDC and Carestream IOSs can provide good patient satisfaction during intraoral scanning. The Carestream IOS obtains better accuracy for the fabrication of all-ceramic SCs.
... Previous clinical studies showed the mean internal adaptation of milled ceramic crowns ranged from 220 to 295 µm [15]. The mean discrepancies ranged from 137 to 175 µm for the same crown in different regions and from 148 to 203 µm for fixed dental prostheses [16,17]. A previous in vitro study evaluated the influence of occlusal resin cement space (50, 100, and 300 µm) on the fatigue performance of anatomical ceramic crowns bonded to a dentin analogue preparation [18]. ...
Article
Full-text available
This study tested whether three different cement layer thicknesses (60, 120 and 180 μm) would provide the same bonding capacity between adhesively luted lithium disilicate and human dentin. Ceramic blocks were cut to 20 blocks with a low-speed diamond saw under cooling water and were then cemented to human flat dentin with an adhesive protocol. The assembly was sectioned into 1 mm2 cross-section beams composed of ceramic/cement/dentin. Cement layer thickness was measured, and three groups were formed. Half of the samples were immediately tested to evaluate the short-term bond strength and the other half were submitted to an aging simulation. The microtensile test was performed in a universal testing machine, and the bond strength (MPa) was calculated. The fractured specimens were examined under stereomicroscopy. Applying the finite element method, the residual stress of polymerization shrinkage according to cement layer thickness was also calculated using first principal stress as analysis criteria. Kruskal–Wallis tests showed that the ‘‘cement layer thickness’’ factor significantly influenced the bond strength results for the aged samples (p = 0.028); however, no statistically significant difference was found between the immediately tested groups (p = 0.569). The higher the cement layer thickness, the higher the residual stress generated at the adhesive interface due to cement polymerization shrinkage. In conclusion, the cement layer thickness does not affect the immediate bond strength in lithium disilicate restorations; however, thinner cement layers are most stable in the short term, showing constant bond strength and lower residual stress.
... Çalışmalarda dijital ölçü kullanılarak hazırlanan protezlerin geleneksel ölçü ile hazırlananlara göre dikkate değer avantajları olduğu gösterilmiştir. 3,4 Marjinal uyum açısından dijital ölçü ile üretilen restorasyonların geleneksel ölçü ile üretilenlere göre daha iyi olduğunu gösteren çalışmalar olmakla birlikte 5,6 , geleneksel ölçü ile üretilenlerin dijital ölçü ile üretilenler ile benzer veya daha üstün olduğunu öne süren çalışmalar da vardır. 7 Dijital ölçü geleneksel ölçüye göre daha az zaman almaktadır.8 ...
Article
Full-text available
Amaç: Bu çalışmanın amacı diş hekimliğinde dijitale doğru bir dönüşüm yaşanılan bu dönemde, dijital diş hekimliği hakkında YouTube™ videolarının içerik kalitesinin ve demografik özelliklerinin değerlendirilmesidir. Gereç ve Yöntemler: Google Trends internet sitesinde dijital diş hekimliği hakkında en çok arama yapılan terimin ‘dijital diş’ olduğu belirlendi. Bu anahtar kelime kullanılarak YouTube’da arama yapıldı ve en fazla görüntülenen 100 video içerisinden kriterleri karşılayan 54 video çalışmaya dahil edildi. Altı başlıktan oluşan bir kullanım kalitesi puan sistemi kullanılarak videolar içerik yönünden zayıf, orta ve iyi olarak sınıflandırıldı. Ayrıca "global kalite skalası" na göre de videolar değerlendirildi. İstatistiksel değerlendirme için verilere Kruskal-Wallis testi ile ikili karşılaştırmalar için Mann-Whitney U testi uygulandı (p < 0.05). Bulgular: Videoların çoğunlukla (% 38.88) diş hekimleri tarafından yüklendiği, % 37.03’ünün dental şirketler tarafından yüklendiği ve bunu TV kanalları tarafından yüklenen videoların takip ettiği (% 24.07) görüldü. Diş hekimi kaynaklı videoların istatistiksel olarak anlamlı şekilde daha fazla görüntülenme (p = 0.036) ve beğenilme sayısına (p = 0.015) sahip olduğu görüldü. Kullanım kalitesi bakımından videoların % 18.51’i içerik olarak iyi, % 44.44’ü orta, % 37.03’ü ise zayıf bulundu. Sonuç: YouTube video platformunda dijital diş hekimliği hakkındaki bilgilerin sınırlı olduğu görüldü. Bu alanda uzman diş hekimlerinin ve akademisyenlerin doğru bilgilerin paylaşılmasında daha fazla rol almasının yararlı olacağı düşünülmektedir.
... In spite of the popularity of computer-aided design and computer-aided manufacturing (CAD-CAM), studies on the ability of numerical control machine tools to accurately produce the designed prosthesis are lacking. 1 These digital systems should limit human bias and standardize the quality of fixed prostheses. 2,3 However, in spite of advanced digital technology, the complex tooth preparation shapes can lead to failures. ...
Article
Statement of problem: In computer-aided design and computer-aided manufacturing (CAD-CAM) dentistry, the CAD of the prosthesis represents the clinical prerequisite design to restore the treated tooth. However, how closely the CAM prosthesis shape matches the CAD, particularly in relation to different materials, is unclear. Purpose: The purpose of this in vitro study was to evaluate onlays designed and manufactured with the same CAD-CAM system but manufactured with different materials. Material and methods: A single standard tessellation language (STL) model was used to produce 6 composite resin onlays, 6 leucite glass-ceramic onlays, and 6 lithium disilicate glass-ceramic onlays. The onlays were digitized by using an X-ray microtomographic protocol with a metrological calibration. The CAD model was then compared with the scans of the different onlays. An analysis by region of interest was then carried out to assess the accuracy and reliability of the dimensional accuracy. Results: The composite resin and the lithium disilicate glass-ceramic had the best dimensional accuracy. The leucite glass-ceramic exhibited a lack of trueness linked to consistent overmilling. The composite resin had less peripheral chipping than the glass-ceramics. Conclusions: The composite resin and the lithium disilicate glass-ceramic material exhibited satisfactory dimensional accuracy. Milling the glass-ceramic before crystallization considerably improved dimensional accuracy.
... Most studies show that there is no difference in the fit of the produced restorations by these two data acquisition approaches [18,19]. Digitally fabricated 3-piece ceramic substructures have a better fit than conventionally fabricated metal substructures [20]. For the digitization to be successful it must drastically improve the user-friendliness, efficiency and cost-effectiveness of dental care. ...
... Most studies show that there is no difference in the fit of the produced restorations by these two data acquisition approaches [18,19]. Digitally fabricated 3-piece ceramic substructures have a better fit than conventionally fabricated metal substructures [20]. For the digitization to be successful it must drastically improve the user-friendliness, efficiency and cost-effectiveness of dental care. ...
Article
Full-text available
By comparing the motivation of the pioneers with the new state of the art of digital dentistry, it gives a good picture of the type and extent of innovations and technological advancements in the last 30 years that have been of influence and whether dentistry was improved by progress and innovations, the breadth and their impact, disruptions and benefits that have or have not occurred and whether material scientists have seized all opportunities. Digitization has led to changes on many fronts and yielded new techniques, systems and interactions that have improved dentistry. Innovation has created opportunities for future research into new materials. Due to digitization and the new state of the art, the patient experience has improved. More restoration options are possible with high durability and better aesthetics. New ways have been developed for effective and efficient interprofessional and clinical-patient interactions. New university curricula enable the training of students towards a new way of learning. Digital dentistry was initially seen as a threat to dental technicians, but this has turned out to be incorrect, so much so that no one doubts the positive contribution that the digitization of dentistry has made anymore. The question of whether 30 years of digitization has added value for dentistry is interesting, although it has permanently changed our way of working.
... The longevity of dental restorations is dependent on numerous factors, one of the most important being their adaptability [5]. Many studies investigate the results for traditional technologies, but fewer investigated both additive and subtractive techniques, compared with traditional ones [6,7]. ...
Article
Full-text available
(1) Background: Traditional metal-ceramic restorations are considered as a standard in the evaluation of new technologies. A critical factor in their longevity is represented by their adaptability; The purpose of this study was to evaluate the marginal and internal gap of ceramic-fused to metal crowns with frameworks obtained by additive manufacturing (AM) technologies and the influence of veneering process on their fit; (2) Methods: Metal-ceramic crowns have been produced by conventional lost-wax technology (T), digital milling (F), selective laser sintering (SLS) and selective laser melting (SLM). The adaptability was assessed using silicone replicas before and after ceramic veneering; (3) Results: The best values were obtained for the milled group followed closely by SLM and SLS, and a significantly higher gap for casted copings. The veneering process did not significantly influence the adaptability of the crowns, regardless of the manufacturing process used for frameworks. The present study promotes additive technologies (AT) as a fast, efficient, and cost-effective alternative to traditional technology. There are fewer steps in which errors can occur when digital technologies are used and the risk of distortion is diminished. (4) Conclusions: CAD/CAM technologies, both additive and subtractive, represent an excellent option to produce time-effective, precise metal-ceramic crowns with excellent adaptation.
... Several clinical studies have reported how these protocols can represent a predictable solution for the fabrication of short-span implant-supported restorations (single crowns [11][12][13] and fixed partial prostheses supported by 4-5 implants [6,14,15]). The application of these protocols has a series of advantages, such as the elimination of the conventional impressions with trays and materials, which have always been unwelcome to patients [16], the simplification of clinical procedures, and the saving of time and money, especially when printing physical models is unnecessary [17]. ...
Article
Full-text available
Purpose: To compare the reliability of five different intraoral scanners (IOSs) in the capture of implant scanbodies (SBs) and to verify the dimensional congruence between the meshes (MEs) of the SBs and the corresponding library file (LF). Methods: A gypsum cast of a fully edentulous maxilla with six implant analogues and SBs screwed on was scanned with five different IOSs (PRIMESCAN®, CS 3700®, MEDIT i-500®, ITERO ELEMENTS 5D®, and Emerald S®). Ten scans were taken for each IOS. The resulting MEs were imported to reverse engineering software for 3D analysis, consisting of the superimposition of the SB LF onto each SB ME. Then, a quantitative and qualitative evaluation of the deviations between MEs and LF was performed. A careful statistical analysis was performed. Results: PRIMESCAN® showed the highest congruence between SB MEs and LF, with the lowest mean absolute deviation (25.5 ± 5.0 μm), immediately followed by CS 3700® (27.0 ± 4.3 μm); the difference between them was not significant (p = 0.1235). PRIMESCAN® showed a significantly higher congruence than MEDIT i-500® (29.8 ± 4.8 μm, p < 0.0001), ITERO ELEMENTS 5D® (34.2 ± 9.3 μm, p < 0.0001), and Emerald S® (38.3 ± 7.8 μm, p < 0.0001). CS 3700® had a significantly higher congruence than MEDIT i-500® (p = 0.0004), ITERO ELEMENTS 5D® (p < 0.0001), and Emerald S® (p < 0.0001). Significant differences were also found between MEDIT i-500® and ITERO ELEMENTS 5D® (p < 0.0001), MEDIT i-500® and Emerald S® (p < 0.0001), and ITERO ELEMENTS 5D® and Emerald S® (p < 0.0001). Significant differences were found among different SBs when scanned with the same IOS. The deviations of the IOSs showed different directions and patterns. With PRIMESCAN®, ITERO ELEMENTS 5D®, and Emerald S®, the MEs were included inside the LF; with CS 3700®, the LF was included in the MEs. MEDIT i-500® showed interpolation between the MEs and LF, with no clear direction for the deviation. Conclusions: Statistically different levels of congruence were found between the SB MEs and the corresponding LF when using different IOSs. Significant differences were also found between different SBs when scanned with the same IOS. Finally, the qualitative evaluation revealed different directions and patterns for the five IOSs.
... Treatment comfort was also reported to be higher for digital impression technique.[19] However, another randomized clinical trial by Benic et al. concluded that there was no difference in working time between conventional impressions and digital impressions and patient comfort was also similar.[32] A recent systematic review by Gallardo et al. concluded that patients were more likely to prefer digital workflow than the conventional technique.[33] ...
Article
Full-text available
Aim: The aim of this systematic review was to investigate the marginal adaptation of three or four unit fixed dental prosthesis (FDP) fabricated with digital impression techniques to those fabricated using any other impression technique. Settings and design: Database/electronic searches were conducted till August 2019 in PUBMED-MEDLINE, SCOPUS, and Cochrane library. To identify published articles, multiple keywords were used to develop a search strategy in various combinations. Manual searching of articles was also done. Clinicaltrials.gov.in WHOICTRP and CTRI websites were also searched. Two independent reviewers (TP and VK) assessed eligibility for inclusion, extracted data, and assessed quality using the Cochrane risk of bias tool. Results: Database search identified 497 citations and four citations through manual search. After removing duplicates and going through abstracts, 23 articles were perused for full-text screening. Two articles met the inclusion criteria; characteristics were described qualitatively, with two studies having overall low risk of bias. Conclusions: Marginal adaptation of FDPs fabricated using the digital and conventional impressions method was within the clinically acceptable limits. However, more robust clinical trials need to be conducted with large sample size to validate the conclusions.
... However, when taking the spacer into consideration, the only significant difference found was that zirconia FDPs had a significantly smaller occlusal gap [35]. Other studies report the spacer settings but fail to use them when drawing conclusions [36,37]. ...
Article
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Purpose: The aim of this study was to review the fit and assess the accuracy of tooth-supported single and multi-unit zirconia fixed dental prostheses. Background: The fit of zirconia restorations has been reported in several studies, but the accuracy of the manufacturing process is seldom discussed or used when drawing conclusions on the fit. Materials and methods: A literature search of articles published in PubMed between 2 March 2013 and 1 February 2018 was performed using clearly defined inclusion and exclusion criteria. 841 articles were found and 767 were excluded after screening the title and abstract. After full-text analysis another 60 articles were excluded which left 14 articles to be included for data extraction. Fit was the mean of distances reported in the studies and accuracy was the fit minus the pre-set spacer Results: For marginal gap of single crowns and multi-unit FDPs combined, the fit was 83 μm and the accuracy was 59 μm. The internal gap fit was 111 μm and the accuracy 61 μm. For the total gap, the fit was 101 μm, and the accuracy of the zirconia restorations was 53 μm. Conclusions: Within the limitations of the present systematic review the fit of zirconia single crowns and multi-unit FDPs may be regarded as clinically acceptable, and the accuracy of the manufacturing of zirconia is ∼60 μm for marginal, internal, and total gap. Also, digital impressions seem to be associated with a smaller gap value.
... At least one investigation reports better marginal fit with digital scans although the differences are both within conventionally acceptable limits [45]. Digitally fabricated 3-unit ceramic frameworks fit better than conventionally fabricated metal framework [46]. ...
Article
Objective: Summarizing the new state of the art of digital dentistry, opens exploration of the type and extent of innovations and technological advances that have impacted - and improved - dentistry. The objective is to describe advances and innovations, the breadth of their impact, disruptions and advantages they produce, and opportunities created for material scientists. Methods: On-line data bases, web searches, and discussions with industry experts, clinicians, and dental researchers informed the content. Emphasis for inclusion was on most recent publications along with innovations presented at trade shows, in press releases, and discovered through discussions leading to web searches for new products. Results: Digital dentistry has caused disruption on many fronts, bringing new techniques, systems, and interactions that have improved dentistry. Innovation has spurred opportunities for material scientists' future research. Significance: With disruptions intrinsic in digital dentistry's new state of the art, patient experience has improved. More restoration options are available delivering longer lifetimes, and better esthetics. Fresh approaches are bringing greater efficiency and accuracy, capitalizing on the interest, capabilities, and skills of those involved. New ways for effective and efficient inter-professional and clinician-patient interactions have evolved. Data can be more efficiently mined for forensic and epidemiological uses. Students have fresh ways of learning. New, often unexpected, partnerships have formed bringing further disruption - and novel advantages. Yes, digital dentistry has been disruptive, but the abundance of positive outcomes argues strongly that it has not been destructive.
... 3 Also, digital impressions combined with CAD/CAM technology allow a completely digital workflow, starting from impression to framework planning, to realization of final work. This completely digital workflow has been demonstrated to be effective in various fields of dentistry, such as prosthodontics, 4 conservative dentistry, 5 and orthodontics. 6 The digital models, however, obtained through intraoral scans are not fully integrated into private practices that are as durable as conventional methods. ...
Article
Background: The comfortness and effectiveness of digital and conventional impression methods in children have not yet been compared. Aim: To assess the digital and conventional impression methods in children in terms of comfort, preference and the time required to take impressions. Design: Digital impressions were taken by using an intraoral scanner, and conventional impressions were taken by using alginate from 28 patients by the same operator. In each impression taking-process, comfort was assessed by both the children and the clinician, and the chairside times were written. Student's t-tests and Mann-Whitney U-tests were used for statistical analyses, and p< .05 was considered to be significant. Results: The digital impression was considered to be more comfortable in the assessments by both the children and the clinician(p< .001). The total time the digital impression took was 465.89±76.71 seconds(s) while that of the conventional impression was 450.25±64.08 s when the chairside times of the two impression methods were compared. There was no statistically significant difference(p= .41). Conclusion: The digital impression method compared to the conventional impression method was found to be both more comfortable and preferable by the children, but there was no difference in terms of the time required to take impressions. This article is protected by copyright. All rights reserved.
Article
O objetivo deste estudo foi realizar uma revisão sistemática da literatura sobre a precisão e a satisfação das técnicas de moldagem digital e convencional em prótese parcial fixa. Seguindo as recomendações PRISMA e a estratégia PICOS, foi realizada uma busca eletrônica nas bases de dados internacionais MEDLINE/PUBMED, LILACS e SCIELO em março de 2024. Foram incluídos apenas estudos clínicos e ensaios clínicos randomizados (ECR) que compararam técnicas de moldagem convencionais e digitais em desdentados parciais, publicados em inglês nos últimos 10 anos. A busca identificou 131 referências, todas do MEDLINE/PUBMED. Após a triagem de título e resumo, 20 artigos foram considerados elegíveis. Sete foram excluídos na etapa de leitura de títulos e resumos e 5 não preencheram os critérios de inclusão, resultando em 8 artigos incluídos na revisão. Este estudo compara a moldagem odontológica digital com a convencional em prótese fixa, visando avaliar a eficácia clínica, o conforto do paciente e os resultados. A moldagem convencional, embora tradicional, enfrenta desafios de precisão e conforto, além de demandar mais tempo. Em contraste, o fluxo digital oferece uma abordagem mais eficiente e confortável, eliminando muitos dos passos tradicionais. Os resultados indicam que a moldagem digital melhora a precisão, reduz o tempo de tratamento e proporciona uma experiência mais confortável para os pacientes. A preferência dos pacientes e profissionais pelo fluxo digital destaca sua importância e eficácia na prática clínica atual. A moldagem digital surge como uma alternativa promissora, com benefícios significativos tanto para os profissionais quanto para os pacientes.
Article
As novas tecnologias utilizadas na Odontologia, como a digitalização de imagens, estão levando a mudanças significativas na obtenção de próteses e infraestruturas protéticas, de funcionamento de softwares. A grande área da engenharia desenvolve processos para fabricação de diversos produtos industrializados com auxílio da tecnologia CAD/CAM. O uso desta técnica vem sendo sugerido na clínica odontológica desde a década de setenta, com o objetivo de simplificar, automatizar e garantir níveis de qualidade com adaptações micrométricas das próteses dentárias. O processo pode envolver diferentes ambientes: industrial, laboratorial ou clínico. O objetivo do presente estudo é revisar de forma integrativa a utilização do escaneamento na Odontologia na área de Prótese Dentária, enfatizando os resultados do seu uso e as diferentes formas de escaneamento e comparando, quando possível, este sistema ao método convencional de moldagem. Notou-se que o escaneamento intraoral resulta em próteses fixas com funcionalidade clínica similar ou melhor do que a moldagem convencional, além de estar relacionada a um conforto aumentado por parte do paciente. Além disto, o escaneamento intraoral reduz o tempo de cadeira do paciente, além de estar associado ao fluxo digital laboratorial mais rápido, o que reduz também o tempo total de fabricação destas próteses, sendo ideal para uma melhor administração do tempo de consultório. Palavras chave: Prótese dentária, Odontologia, Tomógrafos computadorizados
Article
Statement of problem: Although a completely digital workflow has numerous advantages, a physical definitive cast may be especially helpful for the accurate assembly of components of complex complete arch-fixed prostheses, the evaluation of esthetic and occlusion features, or prosthesis fabrication. Research on the accuracy of additive complete arch casts with implants positioned with a large anterior-posterior (A-P) spread is sparse. Purpose: The purpose of this in vitro study was to evaluate the trueness of complete arch 4-implant analog casts with a large A-P distribution fabricated with different 3-dimensional (3D) printers. Material and methods: Ten systems were evaluated representing currently available printing technologies and materials for the additive fabrication of complete arch 4-implant analog casts and compared for deviations in the X-, Y-, and Z-axes from the master model scan (MMS), recorded in standard tessellation language (STL). The MMS was provided to the laboratory selected by the manufacturer, permitting them to create their specific cast with computer-aided design and computer-aided manufacture specific to a particular system, including analog receptacle offset settings. Laboratories fabricated N=10 casts and affixed analogs. A conventional splinted impression and stone cast (CON) was fabricated as a control. The casts were scanned with a precision laboratory scanner (D2000; 3Shape A/S), and files were imported into the Convince metrology software program (3Shape A/S) for comparison with the MMS for mean deviations in the X-, Y-, and Z- axes. A 2-way ANOVA and the Tukey HSD comparison tests were performed between system groups and the 4 implant locations (α=.05). Comparative color maps were used to determine dimensional changes of the edentulous ridges. Results: For 2-dimensional deviations from the MMS in each of the 3 axes, the printer type, implant location, and interaction between those 2 variables were found to be statistically significant (P<.05). Comparisons among printers showed the smallest deviations for Asiga Pro 4K (ASG) and Stratasys Origin One (ORI) printers in both the X- and Y-axes and for CON in the Z-axis. For 3D deviations, comparison among printers indicated that ORI, SprintRay Pro55 S (SPR), and Ackuretta SOL (ACK) had the largest deviations, whereas CON and ASG showed the smallest deviations. Comparison color mapping demonstrates a disparity between printed model dimensional changes and implant analog positioning since the color maps of the casts' ridge crests were not in concordance with the results of the implant analog deviations. Conclusions: ASG, 3D Systems ProJet MJP 2500 Plus (MJP), 3D Systems NextDent 5100 (NEX), Stratasys J5 DentaJet (PJ5), Ivoclar PrograPrint PR5 (PR5), and Prodways ProMaker LD20 (PWY) were similar in terms of 3D deviations to the conventional stone cast control. Comparative color mapping showed the direction and quantity of the dimensional changes of the ridge crest frequently did not correlate with the 3D deviations of implant analog positioning. Implant analog insertion errors were predominantly responsible for analog position 3D deviations rather than the polymerization shrinkage of additive photopolymers.
Article
Objective: To summarize the existing scientific evidence on the effect of distinct intraoral (IOS) and extraoral (EOS) scanners in terms of their accuracy for image acquisition and the marginal/internal adaptation of indirect restorations. Methods: The protocol of this scoping review is available online (https://osf.io/cwua7/). A structured search, with no date restriction, was performed in LILACS, MEDLINE via Pubmed, EMBASE, Web of Science, and Scopus, for articles written in English. The inclusion criteria were studies that considered at least two scanners, regardless of method (intra or extraoral), for the production of tooth-supported restorations. Two independent and blinded researchers screened the studies, collected and analyzed the data descriptively. Results: 103 studies were included (55 on marginal/internal adaptation, 33 on accuracy, 5 on both outcomes, and 10 reviews). Most of them, shown clinically acceptable adaptation (<120 μm). Factors commonly related to the performance of scanners are: use of anti-reflection powders, method of image acquisition, and restoration/tooth characteristics. The need of anti-reflection powders was controversial. Different scanning principles seems to result on similar performance; IOS that combine them could be promising. The most explored systems were Omnicam - IOS, and inEos X5 - EOS, which showed similar performance on marginal/internal adaptation. Scarce studies explored the performance of EOS systems, especially in terms of accuracy. Different restoration designs as single-unit seemed not to modify the performance of scanners. Limited information is available regarding the planned cement space, restorative material and design (multi-unit restorations), as also techniques to measure adaptation. Conclusions: Digital scanners are valid approaches to obtain accurate impressions resulting in clinically acceptable restorations. Systems that uses combined principles of image acquisition seems promising for optimal performance. Based on high discrepancy, the quality of evaluated evidence is low, and well-designed studies are still encouraged, especially considering validated IOS/EOS as a control comparison condition.
Article
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Aim The study aimed to verify compliance of the systematic reviews with the requirements established by the scientific community and demonstrate the validity and reliability of the systematic reviews conducted on the accuracy (marginal adaptation and/or internal adaptation) of the full-coverage fixed prostheses made with digital impressions versus conventional impressions. Methods A search was performed for systematic reviews in three electronic databases, PubMed, Scopus, and Web of Science, as well as in the gray literature. In the search strategy, medical subject heading (MeSH) words were used in PubMed, and free terms were used for the titles and abstracts of each article. Each keyword was separated by the Boolean operator OR and later combined with the Boolean operator AND. Six systematic reviews were included for qualitative synthesis. To assess the methodological quality of the included systematic reviews, the AMSTAR 2 tool was used. Results The search yielded 131 studies, of which 78 remained after removing duplicates. The title and abstract of each chosen study were assessed, and 22 articles were included for full-text reading. Finally, six studies were included, of which three studies were considered to have low confidence, while the other three were considered to have critically low confidence. In addition, the six SRs evaluated the adaptation or marginal fit, while only three studies measured internal adaptation. Conclusion The use of digital impressions in single fixed prostheses maintains a marginal level within the limit of clinical acceptability; however, the methodological quality of systematic reviews is poor, according to the AMSTAR 2 tool.
Technical Report
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the purpose of digital dentistry is the integration of hardware and software in the context of dentistry and, to subsequently promote the development of user-friendly, efficient and cost-effective computer applications for diagnosis and treatment of patients for dental health care over the last 30 years
Article
Objective: The background and clinical understanding of the properties of currently available indirect restorative systems and fabrication methods is, along with manufacturer and evidence-based literature, an important starting point to guide the clinical selection of materials for tooth and/or implant supported reconstructions. Therefore, this review explores most indirect restorative systems available in the market, especially all-ceramic, along with aspects of manufacturing process, clinical survival rates, and esthetic outcomes. Overview: Progressive incorporation of new technologies in the dental field and advancements in materials science have enabled the development/improvement of indirect restorative systems and treatment concepts in oral rehabilitation, resulting in reliable and predictable workflows and successful esthetic and functional outcomes. Indirect restorative systems have evolved from metal ceramics and polymers to glass ceramics, polycrystalline ceramics, and resin-matrix ceramics, aiming to improve not only biological and mechanical properties, but especially the optical properties and esthetic quality of the reconstructions, in attempt to mimic natural teeth. Conclusions: Based on several clinical research, materials, and patient-related parameters, a decision tree for the selection of indirect restorative materials was suggested to guide clinicians in the rehabilitation process. Clinical significance: The pace of materials development is faster than that of clinical research aimed to support their use. Since no single material provides an ideal solution to every case, professionals must continuously seek information from well designed, long-term clinical trials in order to incorporate or not new materials and technological advancements.
Article
Purpose To present the results obtained with a novel sleeveless and keyless guided implant surgery system. Methods Inclusion criteria for this multicenter clinical retrospective study were fully or partially edentulous patients who had been treated with a sleeveless and keyless guided implant surgery system (R2Gate®, Megagen), and who had been rehabilitated with fixed restorations, with a minimum follow-up of 1 year. All surgeries and prosthetic procedures were conducted following the same protocol, and data were obtained from the patients’ medical records. The outcomes were the fit and stability of the surgical guide, any intra-operative and immediate post-operative complications, any biologic and prosthetic complications that occurred during the 1-year follow-up period, implant survival, and prosthetic success. Results Sixty patients were selected for the installation of 124 implants, through a guided procedure: 66 sleeveless, keyless surgical guides were manufactured. The incidence of immediate intra-operative (lack of space: 12.1%; lack of implant stability 2.6%) and immediate post-operative (pain and discomfort: 6.6%; mild swelling 3.3%) complications was low. In total, 112/124 implants (90.3%) were successfully placed with a guided procedure, in 52 patients; among them, 82 (73.2%) were placed with a flapless procedure. Thirty fixtures supported single crowns (SCs), 42 fixed partial dentures (FPDs) and 52 full-arch (FA) restorations. Sixty-two fixed prosthetic restorations (30 SCs, 22 FPDs and 10 FAs) were delivered; among these restorations, 15 (24.1%) were subjected to immediate functional loading. All implants (100%) survived. Two implants had peri-implant mucositis (1.6%), two SCs had abutment screw loosenings (1.6%), two FAs and one FPD had ceramic chipping/fracture (2.4%), for an overall prosthetic success amounting to 88.7%. Conclusions Within the limits of this study, this novel guided surgery system appeared to be clinically reliable; further studies are needed to confirm these results. Statement of Clinical Relevance The use of sleveless and keyless surgical guides can be clinically reliable and may be represent a valid option for the surgeon.
Article
Statement of problem The lack of consensus regarding a standardized set of outcome measurements and noncompliance with current reporting guidelines in clinical trials of tooth-supported fixed dental prostheses (FDPs) hamper interstudy comparability, compromise scientific evidence, and waste research effort and resources in prosthetic dentistry. Purpose The primary objective of this systematic review was to identify all primary and secondary outcome measurements assessed in randomized controlled trials (RCTs) of tooth-supported FDPs. Secondary objectives were to assess their methodological quality by using the Cochrane Collaboration's risk of bias tool (RoB, v2.0) and their reporting quality by means of a standardized 16-item CONSORT assessment tool through published reports. Material and methods An electronic search was conducted in MEDLINE, EMBASE, and Cochrane library to identify all RCT-related articles published in the past 10 years. Differences in RoB were tested with the Pearson chi-square test, and those in CONSORT score with the Student t test. Results A total of 64 RCTs from 79 publications were deemed eligible. The diversity of outcome measures used in the field is apparent. Twenty percent of the included studies had a low RoB, 79% showed some concerns, and 1% had a high RoB. The mean ±standard deviation CONSORT compliance score was 22.56 ±3.17. Trials adhered to the CONSORT statement reported lower RoB than those that did not adhere (P<.001). RCTs with a low RoB reported more comprehensive adherence to CONSORT guidelines than those with some concerns (MD 4 [95% CI 1.52-6.48]; P=.004). Conclusions A standardized core outcome reporting set in clinical research on tooth-supported FDPs remains evident. Adherence to the CONSORT statement continues to be low, with some RoB concerns that can be improved.
Article
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Background/purpose Advancements in digital dentistry and the development of intraoral scanners (IOS) have provided clinicians with an accurate and efficient alternative to analog impressions. The aim of this study was to assess the accuracy of the marginal and internal fit of 5-unit monolithic zirconia fixed dental prostheses (FDPs) fabricated with CAD/CAM technology using direct and indirect digitalization methods. Material and methods Three teeth in a maxillary typodont model were prepared to receive a 5-unit zirconia FDP. Six different groups were created according to the type of scanner (intraoral and extraoral) and the type of workflow. For direct workflow, the typodont was scanned with two different IOS (3Shape Trios 3 [3S-IOS] and Cerec Omnicam [C-IOS]). For indirect workflow, after conventional impressions were obtained, the impressions (IMP) were scanned with two different laboratory scanners (3S-IMP and C-IMP). After the impressions were poured, the stone (STN) casts were scanned with the same laboratory scanners (3S-STN and C-STN). Sixty 5-unit monolithic zirconia FDPs (10 in each group) were designed and milled. The marginal and internal fit was assessed. Results The mean marginal gap values were 78.2±9 μm in the IOS group, 82.6± 9 μm in the IMP group, and 82.6±9 μm in the STN group, indicating no statistically significant differences among groups (p > 0.05). The mean axial gap values were 77.7 ± 10 μm in IOS group, 83.61 ± 15 μm in the IMP group, and 84.5±9 μm in the STN group, indicating no statistically significant differences among groups (p > 0.05). Conclusion The marginal and internal fit of 5-unit monolithic zirconia FDPs fabricated with direct and indirect digital scans were similar. The smallest gap values were observed at the marginal region while the greatest gap values were detected at the occlusal region.
Article
Statement of problem Systematic reviews about the internal and marginal misfits of fixed prostheses have identified a limited number of clinical studies, suggesting the need for further research on the subject. Although the replica technique has been described as suitable for this purpose, few studies have validated it. Purpose The purpose of this in vitro study was to compare the ability of a nondestructive replica technique and a destructive cementation technique to assess internal and marginal misfits of zirconia copings, considering current materials and designs. Material and methods Twelve anatomic prefabricated abutments (Neodent) were used to manufacture zirconia copings following the Ceramill (Amann Girrbach AG) (n=6) and Lava (3M ESPE) (n=6) systems. Replications of the cementation line were obtained with polyvinyl siloxane for the replica technique, and the copings were then cemented and sectioned to obtain 5 surfaces (buccal, palatal, mesial, distal, and incisal) and the linear and angle regions (internal axiogingival and axioincisal angles). The thickness of the cement line and silicone film was measured at 45 reference points on each abutment. A total of 540 measurements were made with an optical microscope with a digital camera at magnifications of ×100 and ×200. Data were analyzed by repeated-measures ANOVA and the Bonferroni multiple comparison tests (α=.05). Results In the internal misfit evaluation, the mean values observed for the cementation technique and replica technique were as follows: angle regions, 70.6 μm and 72.2 μm; linear regions, 59.1 μm and 59.6 μm; incisal surface, 139.0 μm and 139.8 μm; buccal surface, 72.4 μm and 73.8 μm; palatal surface, 73.1 μm and 75.2 μm; mesial surface, 74.1 μm and 73.8 μm; distal surface, 75.0 μm and 76.3 μm; and overall mean, 73.6 μm and 74.8 μm, respectively. In the evaluation of the marginal misfit, the mean values found were: buccal surface, 36.7 μm and 37.8 μm; palatal surface, 37.5 μm and 36.8 μm; mesial surface, 44.0 μm and 43.7 μm; and distal surface, 44.6 μm and 45.2 μm, respectively. No significant differences were found between the 2 techniques for all locations and systems (P>.05). Conclusions Within the limitations of this in vitro study, both techniques presented the same ability to assess the internal and marginal misfits when the location and overall mean averages were evaluated (P>.05).
Article
This comprehensive review of the 2019 restorative dental literature is offered to inform busy dentists regarding remarkable publications and noteworthy progress made in the profession. Developed by the Scientific Investigation Committee of the American Academy of Restorative Dentistry, each author brings discipline-specific expertise to 1 of 8 sections of the report: (1) prosthodontics; (2) periodontics, alveolar bone, and peri-implant tissues; (3) implant dentistry; (4) dental materials and therapeutics; (5) occlusion and temporomandibular disorders; (6) sleep-related breathing disorders; (7) oral medicine and oral and maxillofacial surgery; and (8) dental caries and cariology. The report targets important information likely to influence day-to-day dental treatment decisions. Each review is not intended to stand alone but to update interested readers so that they may visit source material when greater detail is desired. As the profession moves toward evidence-based clinical decision-making, an incredible volume of potentially valuable dental literature continues to increase. It is the intention of this review and its authors to provide assistance in negotiating the extensive dental literature published in 2019. It is our hope that readers find this work useful in the clinical management of dental patients.
Article
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Objective We conducted this study to evaluate satisfaction with conventional clasp-retained and attachment-retained removable partial dentures (RPDs) among patients with partially edentulous maxilla. Methods The crossover trial recruited 10 patients with bilateral free-end partially edentulous maxilla who received a conventional RPD for 3 months, followed by an attachment-retained removable partial denture (ARRPD) for another 3 months. There was no washout period between the two interventions. During follow-up, patients were requested to complete a patient satisfaction questionnaire. This 9-item validated questionnaire measured patient satisfaction with the ease of cleaning, ability to speak, comfort, aesthetics, stability, ability to masticate different types of food, masticatory efficiency, oral condition, and general satisfaction. Results Our comparison of the two treatment modalities showed significantly higher satisfaction with the ARRPD than with the conventional RPD. The ARRPD was preferred due to the ease to clean, speech, comfort, aesthetics, stability, masticatory ability, and masticatory efficiency (p < .05). Conclusion Our study showed higher short-term satisfaction rates in patients with ARRPDs than with the conventional clasp-retained RPDs. The superior aesthetics of ARRPDs are recognized in conjunction with the restoration of the partially edentulous maxilla.
Article
This study evaluated the influence of occlusal resin cement space on the fatigue performance of bonded-leucite crowns to a dentin-analogue material. Leucite anatomical crowns were adhesively cemented to dentin-like preparations having distinct occlusal cement space (50, 100 and 300 μm) (n = 18), and subjected to step-stress fatigue testing (150 N thru 350 N; step-size: 25 N; 20,000 cycles/step; 20 Hz). Fatigue data (load and number of cycles for failure) were analyzed using Kaplan–Meier and Mantel–Cox (log-rank) tests (p <0.05). Fractographic analysis and occlusal internal space measurements were also performed. There was no significant difference for the distinct occlusal cement layer (50 μm: 289 N, 136,111 cycles); 100 μm: 285 N, 132,778 cycles; 300 μm: 246 N, 101,667 cycles). Occlusal internal space analysis showed a mean thickness of 120.4 (50 μm), 174.9 (100 μm) and 337.2 (300 μm). All failures were radial cracks originating at the ceramic-cement interface. Distinct occlusal cement spaces had no effect on the fatigue behavior of anatomical leucite crowns.
Article
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Objective: This study aims to evaluate the effect of sonochemical treatment on the surface of yttria-stabilized tetragonal zirconia (Y-TZP) before and after the final sintering. Material and methods: Twenty-eight Y-TZP discs were divided into four groups (n=7), according to surface treatment: PRE: pre-sintering sonication with 30% nominal power for 15 min; POS: post-sintering sonication with 30% nominal power for 15 min; JAT: air abrasion with 50-μm alumina particles; and CON: control group with no treatment. The POS and JAT groups were sintered before sonication and the PRE group after sonication. Surface roughness was analyzed using confocal microscopy, after which resin cement cylinders were placed on the surface of the Y-TZP discs and subjected to mechanical microshear bond strength test until fracture. Surface roughness and microshear bond strength values underwent ANOVA and the Tukey tests. Results: The surface roughness values for the PRE group (299.91 nm) and the POS group (291.23 nm) were not significantly different (p≥0.05), statistically, and the surface roughness value of the JAT group (925.21 nm) was higher than those of PRE and POS (p=0.007) groups. The mechanical microshear bond strength test showed that there was no statistically significant difference between the groups (p=0.08). Conclusions: Therefore, the results showed that sonochemical treatment modifies the Y-TZP surface and is similar to the well-established sandblasting surface treatment regarding the strength of the bond with the resin cement.
Article
Statement of problem: Clinical trials are needed to evaluate the digital and conventional fabrication technology for providing fixed partial dentures (FPDs). Purpose: The purpose of the second part of this clinical study was to compare the laboratory production time for tooth-supported, 3-unit FPDs by means of computer-aided design and computer-aided manufacturing (CAD-CAM) systems and a conventional workflow. In addition, the quality of the 3-unit framework of each treatment group was evaluated clinically. Material and methods: For each of 10 participants, a 3-unit FPD was fabricated. Zirconia was used as the framework material in the CAD-CAM systems and included Lava C.O.S. CAD software (3M) and centralized CAM (group L); CARES CAD software (Institut Straumann AG) and centralized CAM (group iT); and CEREC Connect CAD software (Dentsply Sirona) and centralized CAM (group C). The noble metal framework in the conventional workflow (group K) was fabricated by means of the traditional lost-wax technique. All frameworks were evaluated clinically before veneering. The time for the fabrication of the cast, the 3-unit framework, and the veneering process was recorded. In addition, chairside time during the clinical appointment for the evaluation of the framework was recorded. The paired Wilcoxon test together with appropriate Bonferroni correction was applied to detect differences among treatment groups (α=.05). Results: The total effective working time (mean ±standard deviation) for the dental technician was 220 ±29 minutes in group L, 217 ±23 minutes in group iT, 262 ±22 minutes in group C, and 370 ±34 minutes in group K. The dental technician spent significantly more time in the conventional workflow than in the digital workflow, independent of the CAD-CAM systems used (P<.001). Conclusions: Irrespective of the CAD-CAM system, the overall laboratory time for the dental technician was significantly less for a digital workflow than for the conventional workflow.
Article
Statement of problem: Clinical trials are needed to evaluate digital and conventional technologies for providing fixed partial dentures. Purpose: The purpose of the first part of this clinical study was to test whether complete-arch digital scans were similar to or better than complete-arch conventional impressions regarding time efficiency and participant and clinician perceptions. Material and methods: Ten participants in need of a posterior tooth-supported 3-unit fixed partial denture were included. Three intraoral digital scanners and subsequent workflows (Lava C.O.S.; 3M [Lava], iTero; Align Technology Inc [iTero], Cerec Bluecam; Dentsply Sirona [Cerec]) were compared with the conventional impression method using polyether (Permadyne; 3M) and the conventional workflow. A computer-generated randomization list was used to determine the sequence of the tested impression procedures for each participant. The time needed for the impression procedures, including the occlusal registration, was assessed. In addition, the participant and clinician perceptions of the comfort and difficulty of the impression were rated by means of visual analog scales. Data were analyzed with the nonparametric paired Wilcoxon test together with an appropriate Bonferroni correction to detect differences among the impression systems (α=.05). Results: The total time for the complete-arch impressions, including the preparation (powdering) and the occlusal registration, was shorter for the conventional impression than for the digital scans (Lava 1091 ±523 seconds, iTero 1313 ±418 seconds, Cerec 1702 ±558 seconds, conventional 658 ±181 seconds). The difference was statistically significant for 2 of the 3 digital scanners (iTero P=.001, Cerec P<.001). The clinicians preferred the conventional impression to the digital scans. Of the scanning systems, the system without the need for powdering was preferred to the systems with powdering. No impression method was clearly preferred over others by the participants. Conclusions: For complete-arch impressions, the conventional impression procedures were objectively less time consuming and subjectively preferred by both clinicians and participants over digital scan procedures.
Article
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Maximum likelihood or restricted maximum likelihood (REML) estimates of the parameters in linear mixed-effects models can be determined using the lmer function in the lme4 package for R. As for most model-fitting functions in R, the model is described in an lmer call by a formula, in this case including both fixed- and random-effects terms. The formula and data together determine a numerical representation of the model from which the profiled deviance or the profiled REML criterion can be evaluated as a function of some of the model parameters. The appropriate criterion is optimized, using one of the constrained optimization functions in R, to provide the parameter estimates. We describe the structure of the model, the steps in evaluating the profiled deviance or REML criterion, and the structure of classes or types that represents such a model. Sufficient detail is included to allow specialization of these structures by users who wish to write functions to fit specialized linear mixed models, such as models incorporating pedigrees or smoothing splines, that are not easily expressible in the formula language used by lmer.
Article
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PURPOSE: Few studies have investigated the marginal accuracy of 3-unit zirconia fixed partial dentures (FPDs) fabricated by computer-aided design/computer-aided manufacturing (CAD/CAM) system. The purpose of this study was to compare the marginal fit of zirconia FPDs made using two CAD/CAM systems with that of metal-ceramic FPDs. MATERIALS AND METHODS: Artificial resin maxillary central and lateral incisors were prepared for 3-unit FPDs and fixed in yellow stone. This model was duplicated to epoxy resin die. On the resin die, 15 three-unit FPDs were fabricated per group (45 in total): Group A, zirconia 3-unit FPDs made with the Everest system; Group B, zirconia 3-unit FPDs made with the Lava system; and Group C, metal-ceramic 3-unit FPDs. They were cemented to resin dies with resin cement. After removal of pontic, each retainer was separated and observed under a microscope (Presize 440C). Marginal gaps of experimental groups were analyzed using one-way ANOVA and Duncan test. RESULTS: Mean marginal gaps of 3-unit FPDs were 60.46 µm for the Everest group, 78.71 µm for the Lava group, and 81.32 µm for the metal-ceramic group. The Everest group demonstrated significantly smaller marginal gap than the Lava and the metal-ceramic groups (P<.05). The marginal gap did not significantly differ between the Lava and the metal-ceramic groups (P>.05). CONCLUSION: The marginal gaps of anterior 3-unit zirconia FPD differed according to CAD/CAM systems, but still fell within clinically acceptable ranges compared with conventional metal-ceramic restoration.
Article
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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.
Article
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The objective of this study was to evaluate, by scanning electron microscopy, the marginal and internal fit of all-ceramic three-unit fixed partial denture (FPD) frames fabricated by computer-assisted design/computer-aided machining (CAD/CAM) and CAM techniques using blocks of infiltration ceramic, high-strength yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) zirconia sinter ceramic, high-strength dense sintered Y-TZP zirconia ceramic, and glass ceramic. Slip-cast infiltration ceramic was used as a traditional control. The cementation interface widths of the FPD frame copings on butt (A) shoulders of Cerec In-Ceram zirconia (A1, 53 +/- 17 microm) were smaller than those of slip-cast In-Ceram zirconia (A6, 113 +/- 25 microm). Cerec Y-TZP zirconia (A2, 53 +/- 9 pm) and DCS Y-TZP zirconia (A4, 32 +/- 6 microm) interfaces were both significantly smaller than those of Cercon Y-TZP zirconia (A5, 120 +/- 6 microm). Internally, A2 (103 +/- 14) interfaces were smaller than A4 interfaces (144 +/- 15 microm). On chamfer shoulders (B), Cerec Y-TZP zirconia (B1, 71 +/- 5 microm) interfaces were smaller than Cercon interfaces (B2, 129 +/- 38 microm); internally, B1 (80 +/- 11 microm) interfaces were smaller than B2 interfaces (130 +/- 12 microm). CAD/CAM produced better marginal and internal accuracy of fit compared to slip casting and CAM techniques.
Article
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The aim of this prospective study was to evaluate the clinical performance of fully sintered hot isostatic pressed yttria-partially-stabilized zirconia (Denzir) 3-unit fixed partial dentures (FPDs). Nineteen 3-unit FPDs were placed in 18 patients. Ten FPDs were placed in the maxilla and 9 in the mandible. Two calibrated examiners evaluated the FPDs independently 1 week (baseline), 1 year, 3 years, and 5 years after placement using the California Dental Association quality evaluation system. All FPDs were intact at the 5-year examination. One FPD lost retention after 12 months but remained intact; it was recemented and is still in function after 5 years. All FPDs were rated satisfactory over 5 years. No changes were seen in terms of color and anatomic form. The number of slightly rough or pitted occlusal surfaces increased approximately 30% over 5 years. Visible evidence of ditching along the margin increased over time, but only for those FPDs luted with zinc phosphate cement. The 5-year results indicate that yttria-partially-stabilized zirconia 3-unit FPDs with anatomically designed frameworks are promising prosthetic alternatives, even in the premolar and molar regions. However, for all-ceramic FPDs with more units in function, further studies are necessary.
Article
Statement of problem: Clinical trials are needed to evaluate the digital and conventional fabrication technology for providing fixed partial dentures (FPDs). Purpose: The purpose of the second part of this clinical study was to compare the laboratory production time for tooth-supported, 3-unit FPDs by means of computer-aided design and computer-aided manufacturing (CAD-CAM) systems and a conventional workflow. In addition, the quality of the 3-unit framework of each treatment group was evaluated clinically. Material and methods: For each of 10 participants, a 3-unit FPD was fabricated. Zirconia was used as the framework material in the CAD-CAM systems and included Lava C.O.S. CAD software (3M) and centralized CAM (group L); CARES CAD software (Institut Straumann AG) and centralized CAM (group iT); and CEREC Connect CAD software (Dentsply Sirona) and centralized CAM (group C). The noble metal framework in the conventional workflow (group K) was fabricated by means of the traditional lost-wax technique. All frameworks were evaluated clinically before veneering. The time for the fabrication of the cast, the 3-unit framework, and the veneering process was recorded. In addition, chairside time during the clinical appointment for the evaluation of the framework was recorded. The paired Wilcoxon test together with appropriate Bonferroni correction was applied to detect differences among treatment groups (α=.05). Results: The total effective working time (mean ±standard deviation) for the dental technician was 220 ±29 minutes in group L, 217 ±23 minutes in group iT, 262 ±22 minutes in group C, and 370 ±34 minutes in group K. The dental technician spent significantly more time in the conventional workflow than in the digital workflow, independent of the CAD-CAM systems used (P<.001). Conclusions: Irrespective of the CAD-CAM system, the overall laboratory time for the dental technician was significantly less for a digital workflow than for the conventional workflow.
Article
Statement of problem: Clinical trials are needed to evaluate digital and conventional technologies for providing fixed partial dentures. Purpose: The purpose of the first part of this clinical study was to test whether complete-arch digital scans were similar to or better than complete-arch conventional impressions regarding time efficiency and participant and clinician perceptions. Material and methods: Ten participants in need of a posterior tooth-supported 3-unit fixed partial denture were included. Three intraoral digital scanners and subsequent workflows (Lava C.O.S.; 3M [Lava], iTero; Align Technology Inc [iTero], Cerec Bluecam; Dentsply Sirona [Cerec]) were compared with the conventional impression method using polyether (Permadyne; 3M) and the conventional workflow. A computer-generated randomization list was used to determine the sequence of the tested impression procedures for each participant. The time needed for the impression procedures, including the occlusal registration, was assessed. In addition, the participant and clinician perceptions of the comfort and difficulty of the impression were rated by means of visual analog scales. Data were analyzed with the nonparametric paired Wilcoxon test together with an appropriate Bonferroni correction to detect differences among the impression systems (α=.05). Results: The total time for the complete-arch impressions, including the preparation (powdering) and the occlusal registration, was shorter for the conventional impression than for the digital scans (Lava 1091 ±523 seconds, iTero 1313 ±418 seconds, Cerec 1702 ±558 seconds, conventional 658 ±181 seconds). The difference was statistically significant for 2 of the 3 digital scanners (iTero P=.001, Cerec P<.001). The clinicians preferred the conventional impression to the digital scans. Of the scanning systems, the system without the need for powdering was preferred to the systems with powdering. No impression method was clearly preferred over others by the participants. Conclusions: For complete-arch impressions, the conventional impression procedures were objectively less time consuming and subjectively preferred by both clinicians and participants over digital scan procedures.
Article
Statement of problem: Trials comparing the overall performance of digital with that of conventional workflows in restorative dentistry are needed. Purpose: The purpose of the third part of a series of investigations was to test whether the marginal and internal fit of monolithic crowns fabricated with fully digital workflows differed from that of crowns fabricated with the conventional workflow. Material and methods: In each of 10 participants, 5 monolithic lithium disilicate crowns were fabricated for the same abutment tooth according to a randomly generated sequence. Digital workflows were applied for the fabrication of 4 crowns using the Lava, iTero, Cerec inLab, and Cerec infinident systems. The conventional workflow included a polyvinyl siloxane impression, manual waxing, and heat-press technique. The discrepancy between the crown and the tooth was registered using the replica technique with polyvinyl siloxane material. The dimensions of the marginal discrepancy (Discrepancymarginal) and the internal discrepancy in 4 different regions of interest (Discrepancyshoulder, Discrepancyaxial, Discrepancycusp, and Discrepancyocclusal) were assessed using light microscopy. Post hoc Student t test with Bonferroni correction was applied to detect differences (α=.05). Results: Discrepancymarginal was 83.6 ±51.1 μm for the Cerec infinident, 90.4 ±66.1 μm for the conventional, 94.3 ±58.3 μm for the Lava, 127.8 ±58.3 μm for the iTero, and 141.5 ±106.2 μm for the Cerec inLab workflow. The differences between the treatment modalities were not statistically significant (P>.05). Discrepancyshoulder was 82.2 ±42.4 μm for the Cerec infinident, 97.2 ±63.8 μm for the conventional, 103.4 ±52.0 μm for the Lava, 133.5 ±73.0 μm for the iTero, and 140.0 ±86.6 μm for the Cerec inLab workflow. Only the differences between the Cerec infinident and the Cerec inLab were statistically significant (P=.036). The conventionally fabricated crowns revealed significantly lower values in Discrepancycusp and Discrepancyocclusal than all the crowns fabricated with digital workflows (P<.05). Conclusions: In terms of marginal crown fit, no significant differences were found between the conventional and digital workflows for the fabrication of monolithic lithium disilicate crowns. In the occlusal regions, the conventionally manufactured crowns revealed better fit than the digitally fabricated crowns. Chairside milling resulted in less favorable crown fit than centralized milling production.
Article
Statement of problem: Trials comparing the overall performance of fully digital and conventional workflows in reconstructive dentistry are needed. Purpose: The purpose of the first part of this randomized controlled clinical trial was to determine whether optical impressions produce different results from conventional impressions with respect to time efficiency and patient and operator perceptions of the clinical workflow. Material and methods: Three digital impressions and 1 conventional impression were made in each of 10 participants according to a randomly generated sequence. The digital systems were Lava COS, iTero, and Cerec Bluecam. The conventional impression was made with the closed-mouth technique and polyvinyl siloxane material. The time needed for powdering, impressions, and interocclusal record was recorded. Patient and clinician perceptions of the procedures were rated by means of visual analog scales. The paired t test with Bonferroni correction was applied to detect differences (α=.05/6=.0083). Results: The mean total working time ±standard deviation amounted to 260 ±66 seconds for the conventional impression, 493 ±193 seconds for Lava, 372 ±126 seconds for iTero, and 357 ±55 seconds for Cerec. The total working time for the conventional impression was significantly lower than that for Lava and Cerec. With regard to the working time without powdering, the differences between the methods were not statistically significant. The patient rating (very uncomfortable=0; comfortable=100) measured 61 ±34 for conventional impression, 71 ±18 for Lava, 66 ±20 for iTero, and 48 ±18 for Cerec. The differences were not statistically significant. The clinician rating (simple=0; very difficult=100) was 13 ±13 for the conventional impression, 54 ±27 for Lava, 22 ±11 for iTero, and 36 ±23 for Cerec. The differences between the conventional impression and Lava and between iTero and Lava were statistically significant. Conclusions: The conventional impression was more time-effective than the digital impressions. In terms of patient comfort, no differences were found between the conventional and the digital techniques. With respect to the clinician perception of difficulty, the conventional impression and the digital impression with iTero revealed more favorable outcomes than the digital impression with Lava.
Article
Statement of problem: For 20 years, the intraoral digital impression technique has been applied to the fabrication of computer aided design/computer aided manufacturing (CAD/CAM) fixed dental prostheses (FDPs). Clinical fit is one of the main determinants of the success of an FDP. Studies of the clinical fit of 3-unit ceramic FDPs made by means of a conventional impression versus a digital impression technology are limited. Purpose: The purpose of this in vitro study was to evaluate and compare the internal fit and marginal fit of CAD/CAM, 3-unit ceramic FDP frameworks fabricated from an intraoral digital impression and a conventional impression. Material and methods: A standard model was designed for a prepared maxillary left canine and second premolar and missing first premolar. The model was scanned with an intraoral digital scanner, exporting stereolithography (STL) files as the experimental group (digital group). The model was used to fabricate 10 stone casts that were scanned with an extraoral scanner, exporting STL files to a computer connected to the scanner as the control group (conventional group). The STL files were used to produce zirconia FDP frameworks with CAD/CAM. These frameworks were seated on the standard model and evaluated for marginal and internal fit. Each framework was segmented into 4 sections per abutment teeth, resulting in 8 sections per framework, and was observed using optical microscopy with ×50 magnification. Four measurement points were selected on each section as marginal discrepancy (P1), mid-axial wall (P2), axio-occusal edge (P3), and central-occlusal point (P4). Results: Mean marginal fit values of the digital group (64 ±16 μm) were significantly smaller than those of the conventional group (76 ±18 μm) (P<.05). The mean internal fit values of the digital group (111 ±34 μm) were significantly smaller than those of the conventional group (132 ±44 μm) (P<.05). Conclusions: CAD/CAM 3-unit zirconia FDP frameworks fabricated from intraoral digital and conventional impressions showed clinically acceptable marginal and internal fit. The marginal and internal fit of frameworks fabricated from the intraoral digital impression system were better than those fabricated from conventional impressions.
Article
Purpose: The purpose of this study was to evaluate the marginal adaptation of fixed dental prosthesis frameworks fabricated by computer-aided design/computer-assisted manufacture (CAD/CAM) with three different systems of data acquisition. Materials and methods: A total of 50 specimens were fabricated as follows: using the conventional method (Ni-Cr) (n = 10); iTero/industrial milling (Group 1, n = 10); Cerec Bluecam/industrial milling (Group 2, n = 10); 3S/industrial milling (Group 3, n = 10); and Cerec BlueCam/Sirona milling (Group 4, n = 10). The specimens were numbered and randomized, and the vertical marginal discrepancy was analyzed. Results: Intraobserver analysis indicated no statistically significant difference (paired t test, P = .822) between periods before and after analysis. The conventional method (321 μm) showed greater discrepancy when compared with the CAD/CAM system (89 μm) (P < .001). The intraoral system showed a lower rate of marginal discrepancy when compared with the extraoral system (3S) (P < .001). The closed system presented a higher marginal discrepancy (114 μm) than the open intraoral system (iTero) at P < .001. In addition, the intraoral system when open showed statistically significant differences in mean marginal discrepancy values compared with the same system in closed condition (P > .05). Conclusion: The CAD/CAM systems showed less marginal discrepancy than the conventional method for the fabrication of the frameworks.
Article
Unlabelled: The aim of this study is to review all the published literature investigating the accuracy of fit of zirconia fixed partial dentures (FPD). A comprehensive electronic search was performed through PubMed (MEDLINE) using Boolean operators to combine the following key words: 'zirconia,''margin,''FPD,''internal,''fit,''gap,''fitting surface,''bridge' and 'fixed prosthesis.' The search was limited to articles written in English, published up to January 2010. In addition, a manual search was also conducted through articles and reference lists retrieved from the electronic search and peer-reviewed journals. A total of 115 articles were retrieved and only 15 met the specified inclusion criteria for the review. Twelve of these articles were in vitro and three of them were in vivo. The selected articles had assessed marginal and/or internal fit of zirconia FPDs against the effect of various parameters that were computer-aided design and computer-aided manufacturing (CAD/CAM) and CAM systems, post-sintered and pre-sintered milling, framework configuration, span length, veneer application and ageing. Conclusions: CAD/CAM, post-sintered milling, straight configuration and shorter span frameworks provided superior results than CAM, pre-sintered milling, curved configuration and longer span frameworks. Veneering zirconia frameworks caused deterioration in fit, while ageing of zirconia had no implications on the fit. Further studies are needed to determine the clinical significance of the differences in the accuracy reported in this review.
Article
This prospective study evaluated the clinical outcome of three-unit posterior fixed dental prostheses (FDPs) made of In-Ceram Zirconia. All 65 FDPs were inserted at the Department of Prosthodontics, School of Dentistry, Kiel, Germany, and cemented with glass-ionomer cement. Follow-ups were performed annually. During a mean observation time of 54.4 months, two FDPs failed (one technical and one biologic failure). Two FDPs debonded and the veneering ceramic fractured in four cases. Three abutment teeth needed endodontic treatment and two additional abutment teeth exhibited secondary caries. Results suggest that posterior three-unit all-ceramic FDPs made from In-Ceram Zirconia may be a viable prosthetic treatment option with an outcome comparable to metal-ceramic FDPs.
Article
Marginal discrepancies of zirconia posterior fixed dental prostheses (FDPs) fabricated using various systems have been assessed to determine the quality of the restorations and facilitate clinical use; however, studies are limited and results are ambiguous because of the sample sizes and measurement methods. The purpose of this in vitro study was to compare changes in marginal fit of posterior fixed dental prostheses of 3 zirconia systems manufactured using CAD/CAM technology and metal ceramic posterior fixed dental protheses fabricated with the conventional lost-wax technique, before and after cementation. Forty standardized master steel dies with 2 abutments simulating first mandibular premolars were fabricated to receive a posterior 3-unit FDP (from first molar to first premolar) and divided into 4 groups (n=10): Lava All-Ceramic System, Procera Bridge Zirconia, VITA In-Ceram 2000 YZ, and metal ceramic (control group). All FDPs were prepared for an internal space of 50 microm. The external marginal gap of the restorations was investigated by measuring 30 points in the middle of the buccal and lingual surfaces; therefore, 60 measurements per abutment were recorded. Measurements were made with an image analysis program on the master steel model before and after conventional cementation with a glass ionomer agent (Ketac Cem Easymix). The data obtained were statistically analyzed using 1-way ANOVA, Duncan's multiple range post hoc test, and Student's paired t test (alpha=.05). No significant differences in the vertical marginal fit before and after cementation were recorded for the analyzed groups. The marginal discrepancy of Procera abutments before and after cementation (9 +/-10 microm and 12 +/-9 microm, respectively) was less than that of the other groups. Significant differences (P=.001) were observed in marginal adaptation between Procera Bridge Zirconia and the other groups. The results of this study showed that cementation did not cause a significant increase in the vertical marginal discrepancies of the FDPs and that an internal space of 50 mum provided a high precision of fit of the restorations. The accuracy of fit achieved for the 3 zirconium oxide groups analyzed was within the range of clinical acceptance, and the discrepancies were lower than in the metal ceramic group. Procera Bridge Zirconia showed the lowest vertical discrepancies.
Article
The aim of this prospective clinical trial was to evaluate the reliability of three- and four-unit posterior fixed partial dentures (FPDs) with zirconia frameworks after 3 years of clinical function. Thirty patients, each needing a posterior FPD to restore one or two missing teeth, were included in the study. Preparation guidelines were: occlusal reduction of 1.5 to 2 mm, axial reduction of 1.5 mm, and circumferential chamfer preparation placed 0.5 mm subgingivally. Frameworks were fabricated using a computer-aided design/computer-assisted manufacture technique. All FPDs were cemented with glass-ionomer cement. At baseline and 12, 24, and 36 months after cementation, survival and success of the zirconia framework and the ceramic veneer were evaluated. To analyze the effect of placement of an all-ceramic restoration on the gingival tissue, Gingival Index, Plaque Index, sulcus bleeding index, and pocket depth at abutment (test) and contralateral analogous teeth (control) were assessed. Data were analyzed by descriptive statistics, the Wilcoxon test, and the McNemar test. Of the 30 initial subjects, 27 patients with 27 zirconia FPDs were examined after a mean testing period of 34.2 months. All FPDs were still in use and unfractured, resulting in a 100% survival rate for the frameworks. One FPD exhibited a major chip after 36 months. The cumulative success rate was 96.3%. No significant differences between the periodontal parameters of the test and control teeth were observed. The Plaque Index revealed significantly higher scores for mesial and distal control teeth at baseline and after 12 and 24 months for distal control teeth. Posterior zirconia-based three- and four-unit FPDs present a reliable treatment modality after medium-term clinical use.
Article
The purpose of this study was to investigate the rate of type I zinc phosphate cement solubility as it relates to the degree of marginal opening. Standardized test samples were constructed that would simulate clinically relevant marginal gaps of 25, 50, 75, and 150 microns and their subsequent cement lines. The study was divided into two phases. Phase 1 evaluated the effects of simple diffusion on cement solubility in a static environment, whereas phase 2 investigated the effects of convective forces on cement dissolution in a dynamic environment. Both the phase 1 and phase 2 studies demonstrated no significant difference in the rate of cement dissolution for the 25-, 50-, and 75-micron test groups. The 150-micron test groups for both studies, however, demonstrated an increase in the rate of cement dissolution. The results of the phase 1 and phase 2 studies should not be compared because different methodologies were used.
Article
The in vitro marginal fit of five different all-ceramic crown systems (In-Ceram, Empress staining technique, Empress veneering technique, Celay feldspathic system, Celay In-Ceram system) was evaluated before and after cyclic preloading in an artificial mouth. The crowns were adhesively luted to extracted natural maxillary incisors prepared with a 90 degrees shoulder. The results were compared to those for porcelain-fused-to-metal (PFM) crowns with circular porcelain-butt margins which were cemented with zinc phosphate cement. The analysis of the marginal discrepancies showed significant (P < 0.001) differences among the groups. Crown cementation increased the marginal gaps significantly (P < 0.01). Empress staining technique crowns showed the smallest marginal gaps (median 47 microm), followed by conventional In-Ceram crowns (median 60 microm) and Empress veneer technique crowns (median 62 microm). Celay In-Ceram crowns displayed marginal openings with a median of 78 microm, followed by Celay feldspathic crowns with a median of 99 microm. The marginal gap of the PFM control crowns showed a median of 64 microm. Ageing in the chewing simulator had no significant influence on the marginal fit of all specimens. The study indicates that all the tested all-ceramic crowns have clinically acceptable margins. However, in vivo investigations of all all-ceramic crown systems should be made before clinical routine.
Article
Color stability, strength, and accuracy of fit are the main requirements for complete-ceramic crowns. The Procera AllCeram crown system is a CAD/CAM system used to fabricate individual complete-ceramic crowns that have a dry sintered, aluminum oxide core and appear to match clinical requirements. However, there are few articles about the clinical fit of all-ceramic crowns. This in vivo study measured the accuracy of fit of Procera AllCeram crowns in anterior and posterior teeth. The clinical fit of 80 anterior and posterior Procera AllCeram crowns was evaluated by a replica technique with a light body silicone to fill space between crown and tooth and a heavy body silicone to stabilize the light body film. After removal from the artificial crowns, the replicas were segmented, and measurements of the film thickness were performed with a light microscope. Medians of mean marginal gap widths were between 80 and 95 microm in anterior teeth and between 90 and 145 microm in posterior teeth. Medians of maximal marginal gap widths ranged from 80 to 180 microm in anterior teeth and from 115 to 245 microm in posterior teeth. The accuracy of fit achieved by Procera AllCeram was comparable to other conventional and innovative systems.
Article
Robust dental systems obtained by computer-aided design and manufacture (CAD/CAM) have been introduced and, in parallel, the strength of the ceramic materials used in fabricating dental crowns has improved. Yet all-ceramic crowns suffer from near-surface damage, limiting their clinical success, especially on posterior teeth. Factors directly associated with CAD/CAM fabrication that contribute to the degree of damage include material selection and machining parameters and strategies. However, a number of additional factors also either create new damage modes or exacerbate subcritical damage, potentially leading to catastrophic failure of the crown. Such factors include post-fabrication manipulations in the laboratory or by the clinician, fatigue associated with natural occlusal function, and stress fields created by compliance or distortion within the supporting tooth structure and/or adhesive material holding the crown to the tooth. Any damage reduces the strength of a crown, increasing the probability of catastrophic failure. The challenge is to understand and manage the combination of competing damage initiation sites and mechanisms, limitations imposed by the demand for aesthetics, and biologically related constraints.
Article
The aim of this clinical study was to compare the internal gaps between abutment teeth and posterior fixed partial dentures (FPDs) fabricated utilizing milled zirconia and cast gold-alloy frameworks. As part of an ongoing randomized controlled clinical trial, 32 three-unit FPDs (16 zirconia and 16 metal-ceramic) in 25 patients were randomly selected for adaptation measurements. During the bisque-stage ceramic try-in, an A-silicone impression material was placed between the abutment teeth and the framework. The internal gap, corresponding to the thickness of the replica, was measured under magnification at the following locations: cervical, axial, and occlusal (cusp-tips and central). The internal gaps of FPDs with zirconia frameworks were significantly larger in cervical, axial, and centro-occlusal regions (cervical: 189.6 +/- 71.8 mum vs. 118.6 +/- 31.5 mum; axial: 140.5 +/- 38.3 mum vs. 95.7 +/- 18.1 mum; and centro-occlusal: 192.0 +/- 66.5 mum vs. 153.1 +/- 69.8 mum). The cervical gaps next to the pontics were significantly larger compared with those of the outer walls in both types of FPDs (zirconia: mean difference 67.7 +/- 114.7 mum; metal-ceramic: mean difference 30.0 +/- 71.2 mum). Posterior three-unit FPDs incorporating milled zirconia frameworks exhibited larger internal gaps than those constructed using conventional metal-ceramic techniques.
Article
CAM (computer-aided manufacturing) and CAD (computer-aided design)/CAM systems facilitate the use of zirconia substructure materials for all-ceramic fixed partial dentures. This in vitro study compared the precision of fit of frameworks milled from semi-sintered zirconia blocks that were designed and machined with two CAD/CAM and one CAM system. Three-unit posterior fixed dental prostheses (FDP) (n=10) were fabricated for standardized dies by: a milling center CAD/CAM system (Etkon), a laboratory CAD/CAM system (Cerec InLab), and a laboratory CAM system (Cercon). After adaptation by a dental technician, the FDP were cemented on definitive dies, embedded and sectioned. The marginal and internal fits were measured under an optical microscope at 50x magnification. A one-way analysis of variance (ANOVA) was used to compare data (alpha=0.05). The mean (S.D.) for the marginal fit and internal fit adaptation were: 29.1 microm (14.0) and 62.7 microm (18.9) for the milling center system, 56.6 microm (19.6) and 73.5 microm (20.6) for the laboratory CAD/CAM system, and 81.4 microm (20.3) and 119.2 microm (37.5) for the laboratory CAM system. One-way ANOVA showed significant differences between systems for marginal fit (P<0.001) and internal fit (P<0.001). All systems showed marginal gaps below 120 microm and were therefore considered clinically acceptable. The CAD/CAM systems were more precise than the CAM system.
The effect of cement thickness on the fracture strength of all-ceramic crowns
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