Fahad A. Al-Harbi

Objective The aim of this study was to evaluate the surface roughness, contact angle, and adhesion of Candida albicans to computer-aided designing/computer-aided manufacturing (CAD/CAM) and heat-polymerized (HP) denture base materials. Materials and Methods Specimens were allocated to six groups based on the composition of studied denture base materials, HP acrylic resin, milled resins (AvaDent and IvoCad), and 3D-printed resins (ASIGA, FormLabs, and NextDent). Ten specimens per group were used for each test (n = 10/test). Surface roughness and contact angles were analyzed using profilometer and goniometer, respectively. Adhesion of C. albicans was counted using colony-forming unit (CFU/mL). Means and standard deviations were calculated, and then one-way analysis of variance (ANOVA), followed by Tukey's post hoc test. Correlation of Candida adhesion and surface parameters was determined by using Pearson's correlation analysis. Results No statistically significant difference was noted in surface roughness between HP, milled, and 3D-printed denture base resins except NextDent, which showed significantly higher roughness in comparison to all other resins (p = 0.001). In terms of contact angle, milled resins had the lowest value, followed by HP, ASIGA, and FormLabs, whereas NextDent showed the highest contact angle (p = 0.001). C. albicans adhesion showed no significant difference between all denture base resins. A positive and significant correlation was found between C. albicans adhesion and contact angle (p = 0.003), while no correlation was reported between C. albicans adhesion and surface roughness (p = 0.523). Conclusion Adhesion of C. albicans was similar in all tested specimens. Surface roughness showed no significant difference between all groups except NextDent, which had the highest value. Milled denture base resins had the lowest contact angle among all groups.

Purpose To evaluate the flexural strength (FS), impact strength (IS), surface roughness (Ra), and hardness of 3D‐printed resin incorporating silicon dioxide nanoparticles (SNPs). Materials and Methods A total of 320 acrylic specimens were fabricated with different dimensions according to test specifications and divided into a control group of heat denture base resin, and 3 test groups (80/test (n = 10) of unmodified, 0.25 wt%, and 0.5 wt% SNPs modified 3D‐printed resin. 10,000 thermal cycles were performed to half of the fabricated specimens. FS, IS (Charpy impact), Ra, and hardness were evaluated and the collected data was analyzed with ANOVA followed by Tukey's post hoc test (α = 0.05). Results Incorporating SNPs into 3D‐printed resin significantly increased the FS, IS (at 0.5%) and hardness compared to unmodified 3D‐printed resin ( p < 0.001). However, the FS of pure 3D‐printed and 3D/SNP‐0.50% resin and IS of all 3D‐printed resin groups were significantly lower than the control group ( p < 0.0001). Hardness of 3D/SNP‐0.25% and 3D/SNP‐0.50% was significantly higher than control and unmodified 3D‐printed resin ( p < 0.0001), with insignificant differences between them. The Ra of all 3D‐printed resin groups were significantly higher than control group ( p < 0.001), while insignificant difference was found between 3D‐printed groups. Thermal cycling significantly reduced FS and hardness for all tested groups, while for IS the reduction was significant only in the control and 3D/SNP‐0.50% groups. Thermal cycling significantly increased Ra of the control group and unmodified 3D‐printed resin ( p < 0.001). Conclusion The addition of SNPs to 3D‐printed denture base resin improved its mechanical properties while Ra was not significantly altered. Thermal cycling adversely affected tested properties, except IS of unmodified 3D‐printed resin and 3D/SNP‐0.25%, and Ra of modified 3D‐printed resin.