This study aimed to measure the effect of storage environment on the hardness, surface roughness and wear ability of CAD/CAM resin-matrix ceramics. A total of 200 rectangular-shaped specimens were obtained by sectioning 5 CAD/CAM blocks; Crystal Ultra (CU), Vita Enamic (VE), Lava Ultimate (LU), Cerasmart (CS) and Vita blocks Mark II (MII). Microhardness and surface roughness were measured at baseline and after 7 days of immersion either in saliva or cola (n = 10). The wear ability of the CAD/CAM materials against steatite-ceramics antagonist was determined using a chewing simulator. The data were statistically analyzed using factorial ANOVA followed by post hoc Bonferroni multiple comparison tests (p < 0.05). The independent factors significantly influenced the microhardness and surface roughness (p < 0.05). The highest VHN was observed in MII at baseline (586.97 ± 13.95), while CU showed the lowest VHN after 7 days of immersion in cola (68.3 ± 1.89). On the contrary, the highest Ra was observed after 120,000 chewing cycles for the VE specimens (1.09 ± 0.43 µm) immersed in cola, while LU showed the lowest Ra at baseline (0.07 ± 0.01 µm). The highest % mass loss of the antagonist was observed with MII immersed in cola (1.801%), while CS demonstrated the lowest % mass loss of 0.004% and 0.007% in AS and cola, respectively. This study confirms that the surface properties of tested CAD/CAM materials are susceptible to degradation in an acidic environment except for hardness and wear of CS material.

Purpose: To evaluate the fracture resistance of zirconia overlays, considering various preparation designs and the presence of endodontic access.Materials and Methods: Ninety translucent zirconia (5Y‐PSZ) overlay restorations were divided into six groups (n = 15/group) based on different preparation designs, with and without endodontic access: chamfer margin 4 mm above the gingival level without (group 1) and with endodontic access (group 2); margin 2 mm above the gingival level without (group 3) and with endodontic access (group 4); overlay with no chamfer margin without (group 5) and with endodontic access (group 6). Restorations were bonded to mandibular first molar resin dies, and the groups with endodontic access were sealed with flowable resin composite. All restorations underwent 100,000 cycles of thermal cycling between 5°C and 55°C, followed by loading until fracture. Maximum load and fracture resistance were recorded. ANOVA with Tukey post‐hoc tests were used for statistical comparison (α < 0.05).Results: Fracture resistance significantly varied among overlay designs with and without endodontic access (p < 0.001), except for the no‐margin overlays (groups 5 and 6). Overlays with a 2 mm margin above the gingival margin with endodontic access (group 4) exhibited significantly higher fracture resistance compared to both the 4‐mm supragingival (group 2) and no‐margin (group 6) designs, even when compared to their respective intact groups (groups 1 and 5). There were no significant differences between the no‐margin and 4‐mm supragingival overlays.Conclusion: The more extensive zirconia overlay for mandibular molars is the first choice since the 2 mm margin above the gingival level design withstood considerable loads even after undergoing endodontic access. A no‐margin overlay is preferred over the 4‐mm supragingival design as it preserves more tooth structure and there was no outcome difference, irrespective of endodontic access. Caution is warranted in interpreting these findings due to the in vitro nature of the study.

Objectives: The aim of this study was to assess the relationship between tooth shade among different groups of patients according to their age, gender, and skin color in a Saudi population. Materials and methods: Participants were divided based on age into Group 1 (10–20 years), Group 2 (21–30 years), Group 3 (31–40 years), and Group 4 (41+ years), and according to gender. Tooth shade was measured by Vita easyshade, Shade scanner, 3D Master shade system. The skin color was determined according to the Firzpatrick Scale. It consists of six shades, namely: I, II, III, IV, V, and VI. The skin complexion of the participants was divided into six categories: white/very fair, fair, light brown, moderate brown, dark brown, and black. Results: One hundred and ninety-eight individuals were recruited. Around 70% were males. Females had 25.4% A2 followed by 22% A1, and 22% A3 shade types, while males had B3 shade (18%) followed by A2 and A3 (15.8%). A statistically significant difference was observed between shade and gender (p < 0.05). A statistically significant difference was observed between shade and age group (p < 0.05), where increased age was correlated with darker teeth shades. Shade A1 was correlated with type I skin color in 57.1% of individuals. Skin color type II had A2 as a dominant shade by 34.1%. A2 and A3 shades were equally observed in skin color III by 20.3%. Overall, statistically significant differences were observed between shade and skin color groups (p < 0.05). Conclusions: In conclusion, the most frequent classical shade noted among male and female participants was shade type A, which represents reddish brownish. Group 2 (21–30 years) had the B3 shade as the most prominent shade type among age groups. Gender, age, and skin types all showed a significant relation with the tooth shade.

To assess the influence of three different wash solutions on the flexural strength (FS), elastic modulus (E), surface microhardness (VHN), surface roughness, water sorption (Wsp), and solubility (Wsl) of a 3D-printed glass-reinforced composite resin (3D-CR). VarseoSmile Crown Plus was printed at a 50 µm layer thickness and a 90° build angle. Three test groups were formed based on the ultrasonic bath wash solution: InovaPrint Wash (Group 1), 96 % ethanol (Group 2), and 90 % denatured ethyl alcohol (Group 3). Thirty bar-shaped specimens (25 × 2 × 2 mm³), ten per group, were produced to measure FS and E using a three-point bending test, while five disk-shaped specimens (Ø 15 × 3 mm²) per group were employed to evaluate VHN. Both tests were conducted under dry conditions. Additionally, another set of five specimens (Ø 15 × 3 mm²) per group was used to assess surface roughness before and after simulated toothbrushing, while five disk-shaped specimens (Ø 15 × 1 mm²) were utilized to determine Wsp and Wsl over 28 days. Kruskal-Wallis and Bonferroni post hoc tests were applied for statistical group comparisons. The Kruskal-Wallis test showed a significant difference between the groups in terms of FS (p = .008), E (p = .004) and in VHN (p = .001). Variations among groups were notable in Wsp and Wsl at 21 and 28 days (p = .001). Regarding the surface roughness, the specimens exhibited values surpassing the clinical acceptability threshold (0.2 μm) before and after brushing. These findings underscore the importance of selecting appropriate washing protocols to optimize the long-term performance of 3D-printed composite resins. Optimizing the washing protocol can mitigate the degradation of mechanical and surface properties in 3D-printed composite resins. This is a critical consideration for ensuring the long-term success of definitive restorations.