No abstract

The study purposed to investigate the biocompatibility and sustainability of two computer-aided design/computer-aided manufacturing (CAD/CAM) resin-based composites compared to a resin-modified ceramic in terms of surface roughness, biofilm formation, cytotoxicity, genotoxicity, and cellular changes observed under transmission electron microscopy (TEM). Three CAD/CAM blocks were used, two resin-based composites [Brilliant Crios (BC) and Cerasmart, (CS) and one hybrid ceramic (Vita Enamic (EN)]. Each block was sectioned into 10 × 12 × 2 mm specimens, followed by finishing and polishing. Each specimen was evaluated for surface roughness using 3D optical profilometry and scanned by scanning electron microscopy. Biofilm formation and its relation to surface roughness have been investigated for all tested materials. A Hep-2 cell line was used to investigate the viability through MTT assay. The cytotoxicity of the materials was measured at 24, 48, and 168 h. The activity of P53, caspase 3, and cytochrome C was evaluated to detect the genotoxicity of different groups, followed by TEM tracking of the cellular changes. Statistical analysis was implemented by utilizing a one-way analysis of variance test. The significance was set at P ≤ 0.05. With regard to the surface roughness, no statistically significant differences were shown between groups. BC possessed the highest biofilm formation value, followed by EN and CS, with no significance between them. No correlation between surface roughness of tested materials and biofilm formation was shown. Considering viability, the highest values were recorded for EN, whereas BC showed the lowest values. P53-fold changes in EN were significantly the lowest, indicating less genotoxicity. Within the current study’s limitations, BC showed the highest biofilm formation. However, no significant surface roughness difference or correlation with biofilm formation was observed in tested materials. EN showed the lowest cytotoxicity and the highest viability. EN revealed the best compatibility performance among tested materials. On the contrary, the BC exhibited fewer preferences.

Statement of the problem:The wide use of digital dentistry in fixed prosthodontics using 3D printers and CAD/CAM in fabricating crowns and partial fixed dental prosthesis created a need for more information about their marginal gap and internal fit.Purpose: This study aimed to evaluate the effect of fabrication technique using CAD/CAM manufactured and heat pressed lithium dislicate crowns made from milled wax and 3D printed resin patterns on their marginal gap and internal fit. Material & Methods:A total of 50 prepared mandibular first molar resin models were used and divided into two main groups according to their fabrication phase: Patterns group and fully fabricated crowns group. Patterns group was subdivided into milled wax patterns (W) (n=10) and 3D printed resin patterns (P) (n=10). Fully fabricated crowns group was subdivided according to fabrication technique of lithium disilicate crowns into: Machinable ceramics (M), using IPS e-max CAD blocks (n=10), Pressable ceramics (Pw), using IPS e-max press ingots following wax milling (n=10) and Pressable ceramics (Pp), using IPS e-max press ingots following 3D resin printing (n=10). All patterns and ceramic crowns were cemented with Rely-X self-adhesive resin cement. Marginal and internal adaptations were measured using SEM at 300 × magnification. Kruskal-Wallis and Wilcoxon signed-rank tests were applied to compare between the groups. Data were presented as median and range values. The significance level was set at P ≤ 0.05.Results: P group showed a significant higher median total marginal gap of 111.4 μm (80.8-139.7) than W group of 51.3 μm (45.1-57.8) before heat pressing. While M group showed the significant highest median marginal gap of 138.4 μm (83.4-191.8) and no significant difference between heat pressed groups (Pw and Pp) (P ≤ .05). Regarding changes after heat pressing, Pw group showed no significant decrease, while Pp group showed a significant decrease in median total marginal gap. For internal fit, there was no significant difference between the pattern groups (2780)

Purpose To verify whether 3D surface deviation analysis software can detect the surface changes of composite veneered polyetheretherketone posterior crowns following wear simulation compared to optical digital profilometry. Materials and methods Twenty dental crowns, fabricated from CAD‐CAM polyetheretherketone (PEEK) and veneered with high impact polymer composite (HIPC), were subjected to wear test (50N, 5/55°C; 120,000 chewing cycles). Optical digital profilometry and 3D surface deviation using Geomagic design X software was used before and after the wear test to measure volumetric wear loss (mm3). The data were statistically analyzed with Wilcoxon signed‐rank test to compare the two methodologies. The significance level was set at p ≤ 0.05. Results There was no statistically significant difference between the two assessment methods (p‐value = 0.075, Effect size = 0.854). Regarding the optical digital profilometry analysis, HIPC veneered PEEK crowns showed 0.01686 (0.018‐0.02155) mm3 as a median volumetric wear loss value. While the crowns analyzed by 3D surface deviation showed –0.0398 (–0.0913 to –0.0042) mm3 as a median volumetric loss value (p‐value = 0.075, Effect size = 0.854). In addition, there was no statistically significant correlation between wear measurements by optical digital profilometry and 3D surface deviation analyses (ρ = –0.177, p‐value = 0.685). Conclusions There was no significant difference or correlation between optical digital profilometry and 3D surface deviation analyses for volumetric wear loss of veneered PEEK crowns.

Statement of problem: Veneered polyether ether ketone (PEEK) is a recent alternative choice for fixed dental prostheses. There is a lack of data about the color stability of veneered CAD/CAM PEEK crowns using different veneering composite techniques. Purpose: To verify the effect of thermocycling and different mouth rinses on color stability of CAD/CAM composite versus conventional nanohybrid composite veneered PEEK crowns. Methods: Forty-two duplicated epoxy resin dies of prepared mandibular first molar to receive a ceramic crown were fabricated. 42 CAD/CAM PEEK cores were fabricated and divided into two groups (n=21) based on the veneering technique; group (C): nanohybrid crea.lign composite veneered PEEK cores (control) and group (H): HIPC veneered PEEK cores. Each group was further subdivided based on the mouth rinse into 3 groups (n=7): Listerine-alcohol free, Hexitol and Distilled Water (control). The color at baseline, after thermocycling equivalent to clinical 6 months service and 1-week immersion in mouth rinses were measured utilizing a spectrophotometer. The data were statistically analyzed using ANOVA, pair-wise Tukey's post-hoc and student t-tests to reveal the significance between groups (P ≤ 0.05). Results: All specimens showed visually unperceptible color differences after thermocycling and immersing in mouth rinses (∆E*<3.3). Based on material, C group showed statistically significant higher color change values than H group. ANOVA test revealed that the highest color change was for Hexitol followed by Listerine then Distilled Water (p=<0.0001<0.05). Tukey's post-hoc test showed a non-significant difference between Hexitol and Listerine. The interaction between the effect of mouth rinses and type of veneering composite materials was statistically non-significant for C group (P>0.05) while significant for H group (P<0.05). Conclusions: Although visually nonperceptible, HIPC or nanohybrid composite veneered PEEK crowns showed a color difference after thermocycling and immersion in different mouth rinses.