Three-Dimensional Digital Evaluation of the Fit of Endocrowns Fabricated from Different CAD/CAM Materials

Purpose A wide variety of CAD/CAM materials are available for single‐tooth restorations. CAD/CAM material characteristics are different and may influence CAM fabrication accuracy. There is no study investigating the influence of different CAD/CAM materials on the final fit of the restoration. The aim of this study was to evaluate the fit of endocrowns fabricated from different CAD/CAM materials using a new 3D evaluation method with an intraoral scanning system. The null hypothesis was that there are no significant differences for the fitting accuracy of different CAD/CAM materials. Materials and Methods Preparation for an endocrown was performed on a maxillary right first molar on a typodont, and restorations were fabricated with a chairside CAD/CAM system (CEREC Omnicam, MCXL). Three groups using three different CAD/CAM materials were established (each n = 10): zirconia‐reinforced lithium silicate ceramic (Celtra Duo; CD), leucite‐reinforced silicate ceramic (Empress CAD; EM), resin nanoceramic (Lava Ultimate; LU). A 3D digital measurement technique (OraCheck, Cyfex AG) using an intraoral scanner (CEREC Omnicam) was used to measure the difference in fit between the three materials for a master endocrown preparation. The preparation scan and the endocrown fit scan were matched with special difference analysis software OraCheck. Three areas were selected for fitting accuracy measurements: margin (MA), axial (AX), occlusal (OC). Statistical analysis was performed using 80% percentile, one‐way ANOVA, and post‐hoc Scheffé test. Significance level was set to p = 0.05. Results Results varied from best 88.9 ± 7.7 μm for marginal fit of resin nanoceramic restorations (LU_MA) to worst 182.3 ± 24.0 μm for occlusal fit of zirconia‐reinforced lithium silicate restorations (CD_OC). Statistically significant differences were found both within and among the test groups. Group CD performed statistically significantly different from group LU for marginal fit (MA) and axial fit (AX) (p 0.05). Deviation pattern for differences was visually analyzed with a color‐coded scheme for each restoration. Conclusions Statistically significant differences were found for different CAD/CAM materials if the CAM procedure was identical. Within the limitations of this study, the choice of CAD/CAM material may influence the fitting accuracy of CAD/CAM‐fabricated restorations

Digital evaluation of the fit of zirconia-reinforced lithium silicate crowns with a new three-dimensional approach

OBJECTIVE: Several methods for the evaluation of fit of computer-aided design/computer-assisted manufacture (CAD/CAM)-fabricated restorations have been described. In the study, digital models were recorded with an intraoral scanning device and were measured using a new three-dimensional (3D) computer technique to evaluate restoration internal fit. The aim of the study was to evaluate the internal adaptation and fit of chairside CAD/CAM-fabricated zirconia-reinforced lithium silicate ceramic crowns fabricated with different post-milling protocols. The null hypothesis was that different post-milling protocols did not influence the fitting accuracy of zirconia-reinforced lithium silicate restorations. METHOD AND MATERIALS: A master all-ceramic crown preparation was completed on a maxillary right first molar on a typodont. Twenty zirconia-reinforced lithium silicate ceramic crowns (Celtra Duo, Dentsply Sirona) were designed and milled using a chairside CAD/CAM system (CEREC Omnicam, Dentsply Sirona). The 20 crowns were randomly divided into two groups based on post-milling protocols: no manipulation after milling (Group MI) and oven fired-glazing after milling (Group FG). A 3D computer method was used to evaluate the internal adaptation of the crowns. This was based on a subtractive analysis of a digital scan of the crown preparation and a digital scan of the thickness of the cement space over the crown preparation as recorded by a polyvinylsiloxane (PVS) impression material. The preparation scan and PVS scan were matched in 3D and a 3D difference analysis was performed with a software program (OraCheck, Cyfex). Three areas of internal adaptation and fit were selected for analysis: margin (MA), axial wall (AX), and occlusal surface (OC). Statistical analysis was performed using 80% percentile and one-way ANOVA with post-hoc Scheffé test (P = .05). RESULTS: The closest internal adaptation of the crowns was measured at the axial wall with 102.0 ± 11.7 µm for group MI-AX and 106.3 ± 29.3 µm for group FG-AX. The largest internal adaptation of the crowns was measured for the occlusal surface with 258.9 ± 39.2 µm for group MI-OC and 260.6 ± 55.0 µm for group FG-OC. No statistically significant differences were found for the post-milling protocols (P > .05). The 3D difference pattern was visually analyzed for each area with a color-coded scheme. CONCLUSION: Post-milling processing did not affect the internal adaptation of zirconia-reinforced lithium silicate crowns fabricated with a chairside CAD/CAM technique. The new 3D computer technique for the evaluation of fit of restorations may be highly promising and has the opportunity to be applied to clinical studies

Surface Evaluation of Resilient CAD/CAM ceramics after Contouring and Polishing

ObjectiveThis in‐vitro study measured the differences in surface roughness for computer assisted design/computer assisted manufacturing (CAD/CAM) resilient ceramic and CAD/CAM composite materials.Materials and MethodsThe materials included Lava Ultimate (3 M), Cerasmart (GC America), Vita Enamic (Vita Zahnfabrik), and Brilliant Crios (Coltene). One calibrated operator polished each material with three polishing sytems: spiral polishers (Diacomp FeatherLite/Brasseler), rubbercup polishers (Enhance/DentsplyCaulk), and brush‐paste (Diashine/VH Technologies). Surface roughness was assessed using a confocal laser microscope (Lext OLS4000/Olympus).ResultsA two‐way ANOVA revealed statistically significant differences in mean surface roughness values (Sa) among materials and polishers. Tukey multiple comparisons showed that mean Sa values for Lava Ultimate, Enamic, Cerasmart and Brilliant Crios polished with brush‐paste as well as Lava Ultimate and Cerasmart values polished with spiral polishers were not significantly different from each other.ConclusionsThe finished surfaces were significantly smoother than milled surfaces for all materials. The brush‐paste polishing technique created the lowest surface roughness values for all CAD/CAM materials and values were comparable to what was achieved by spiral polishers for Lava Ultimate and Cerasmart. Rubber polishers did not provide a clinically smooth surface for CAD/CAM resilient ceramic/composite materials.Clinical significanceThe results of the study indicate that polishing creates smooth surfaces for CAD/CAM resilient ceramic and CAD/CAM composite restorations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/168463/1/jerd12735_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168463/2/jerd12735.pd