Objectives: The disinfection of fabricated prostheses is crucial to prevent cross-infection between dental laboratories and clinics. However, there is a lack of information about the effects of chemical disinfection on 3D-printed denture base resins. This study aimed to evaluate the impact of different disinfectants on the flexural strength, elastic modulus, micro-hardness, surface roughness (Ra), and change in color of 3D-printed and conventional heat-polymerized (HP) denture base resins (DBRs). Methods: A total of 240 specimens (80 bar-shaped (64 × 10 × 3.3 mm) and 160 disk-shaped (10 × 2 mm)) were made from HP and 3D-printed DBRs. For each resin, the specimens were divided into four groups (n = 10) according to the disinfectant solution. One remained in water without disinfection as a control group, while the other three groups were disinfected using 1% sodium hypochlorite, 2% glutaraldehyde, or 10% Micro 10+ for 30 min. The flexural strength, elastic modulus, micro-hardness, Ra, and color change were measured. The collected data were statistically analyzed using a two-way ANOVA and Tukey’s post hoc test (α = 0.05). Results: A significant decrease in flexural strength, elastic modulus, and hardness was found with sodium hypochlorite (p < 0.05). When comparing the resins per solution, the 3D-printed resin showed a significant decrease in flexural strength, elastic modulus, and hardness compared with PMMA (p < 0.001), while no change was found in the Ra of both resins with all disinfectants (p > 0.05). Disinfecting with sodium hypochlorite resulted in a significant increase in color change for both resins (p < 0.05); however, all the changes were within clinically acceptable limits. Sodium hypochlorite showed the highest color change, while 2% glutaraldehyde and 10% Micro 10+ showed no significant changes in the tested properties (p > 0.05). Conclusions: Neither resin showed a change in surface roughness with immersion in disinfectants. Sodium hypochlorite had an adverse effect on the flexural properties, hardness, and change in color of the PMMA and 3D-printed DBRs, while the other disinfectants had no effect on the tested properties.

Background/Objectives: The dental industry is continuously developing high-performance polymer (HPP) materials with different qualities for denture frameworks. The aim of this in vitro study was to assess how thermal ageing (TA) affects the flexural strength (FS) and microhardness of two different HPP materials: Nanoksa G-plus and Bio-HPP/PEEK. Methods: The TA process was carried out for 5000 cycles at 5 °C and 55 °C in distilled water. To assess FS, a total of 40 bar-shaped specimens measuring 65.0 mm × 10.0 mm × 2.5 mm (20 per group) were obtained; TA and No-TA (NTA) subgroups were prepared for each material group (10 per subgroup); and a three-point bending test was conducted using an Instron universal testing machine. Each specimen that fractured during the FS test was subjected to microhardness measurement using a Vickers hardness tester. The mean FS and microhardness of the TA and NTA specimens were statistically examined using the t-test. Results: Both the TA and NTA Bio-HPP/PEEK specimens exhibited significantly greater (p < 0.0001) microhardness and FS qualities than the Nanoksa G-Plus specimens. The FS and microhardness of the Bio-HPP/PEEK and Nanoksa G-Plus materials significantly decreased (p < 0.05) after TA. Conclusions: The Bio-HPP/PEEK material showed better FS and microhardness properties than the Nanoksa G-Plus material. TA considerably decreased the FS and microhardness of the Bio-HPP/PEEK and Nanoksa G-Plus materials.

Objective: This study was aimed to evaluate the effect of incorporation of chitosan nanoparticles (Cs/NPs) on flexural strength, impact strength, fracture toughness as well as, water sorption and solubility of thermoplastic resin material. Materials and Methods: Cs/NPs (Nano-gate Company, Egypt) was incorporated into thermoplastic resin (Bre-flex, Bredenttm, Germany) with different concentration (1.5 wt., 5wt., and 7 wt.%). This study was divided into four main groups; unmodified “control group” and four modified groups according to the concentration of the incorporated Cs/NPs. Results: The results of this study revealed that; the incorporation of Cs/NPs decrease the flexural strength, impact strength, and fracture toughness of thermoplastic resin. While, the water sorption and solubility of modified thermoplastic resin were increased. Conclusion: The incorporation of Cs/NPs into thermoplastic resin at different concentrations could adversely affects its flexural strength, impact strength, fracture toughness as well as its water sorption and solubility. Key Wards: Chitosan, Nanoparticles, Mechanical properties, physical properties, Thermoplastic resin.

Objective: This study was aimed to evaluate the effect of incorporation of two-different nanoparticles; silica (SiO2), and zirconia (ZrO2) on flexural strength, impact strength, as well as, water sorption and solubility of thermoplastic resin material. Materials and Methods: Two nanoparticles SiO2-NPs, and ZrO2-NPs (Nano-gate Company, Egypt) were incorporated into thermoplastic resin (Bre-flex, Bredenttm, Germany) with different concentration (1.5 and 7 wt.%). This study was divided into five main groups; unmodified “control group” and four modified groups according to the type and concentration of the incorporated nanoparticles. Results: The results of this study revealed that; the incorporation of 1.5 wt.% SiO2-NPs significantly improve the flexural strength of thermoplastic resin. While, the incorporation of SiO2-NPs, and ZrO2-NPs nanoparticles insignificantly decrease its impact strength. However, they significantly increase water sorption and solubility of thermoplastic resin. Conclusion: The incorporation of nanoparticles into thermoplastic resin at different concentrations could negatively affects its flexural strength, impact strength, as well as its water sorption and solubility. Key Wards: Silica Nanoparticles, Mechanical properties, Thermoplastic resin, Zirconia.