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.

Aim: To evaluate flexural strength (FS) and micro-hardness of poly(methylmethacrylate) (PMMA) denture base material modified with Zirconium oxide (ZrO2), titanium oxide (TiO2) and zinc oxide (ZnO) nanoparticles powder with different concentration (1.5, 3 and 5% ) Subjects and Methods: Test specimens of PMMA of dimensions (65 ×10 × 2.5 mm) were made from heat-cured acrylic resin served as control group Another nine group were made of PMMA containing 1.5, 3, and 5% (w/w) (ZrO2), (TiO2) and (ZnO) nanoparticles. Two types of mechanical tests were performed on the samples: flexural strength and hardness. Results: Statistical analysis results revealed that non-significant increase in flexural strength of heat cured reinforced with ZrO2 Nps and ZnO Nps for all concentrations. While adding 1.5% and 5% of TiO2 Nps showed significant increase in flexural strength but 3% showed significant decrease values. Results revealed that non-significant decrease in hardness of heat cured reinforced with ZrO2 Nps ,TiO2 Nps, and ZnO Nps for all concentrations except 3% of heat cured reinforced with TiO2 Nps which showed non-significant increase in hardness. Conclusions: It was discovered that adding of 1.5and 5% Tio2 Nps to the used denture base materials would improve the flexural strength of the denture base materials. Also, adding 1.5, 3 and 5 % ZrO2, Tio2, and ZnO Nps reduces the microhardness.

This article assesses the effect of different ferrule preparations on the stress distribution in the primary second molar restored with zirconia crown. Four finite element models were created to simulate different ferrule heights: M1 (0 mm), M2 (1 mm), M3 (1.5 mm), and M4 (2 mm). A lower primary second molar was scanned to create a solid model, which was imported into finite element analysis software. Simulations included varying ferrule heights, material properties, and meshing. Models were subjected to 330 N occlusal loads at vertical, oblique, and lateral angles. The analysis revealed that stress within the endocrown body increased with greater ferrule height under vertical loading. Conversely, stress levels decreased with increased ferrule height under oblique and lateral loads. Under vertical load, peak stresses were recorded as follows: endocrown body (219.5 MPa for M1), cement layer (11.7 MPa for M1 and M4), remaining tooth (36 MPa for M1), cortical bone (59.7 MPa for M1), and cancellous bone (8.7 MPa for M1 and M4). Under oblique load, stress values increased as follows: cement layer (62.9 MPa for M4), remaining tooth (59 MPa for M1), and endocrown body (203 MPa for M1). Under lateral load, stress values increased as follows: endocrown body (321 MPa for M1), cement layer (100 MPa for M4), remaining tooth (94 MPa for M1), cortical bone (154 MPa for M1), and cancellous bone (15 MPa for M1). Ferrule height significantly influences stress distribution in the tooth structure and supporting bone. Higher ferrule heights enhance structural stability by reducing stress on underlying components.

Objectives: The aim of the present study was to evaluate the sealing ‎ability of experimental nano sealers (nano calcium hydroxide and nano ‎bioactive glass) and to compare it with the commercial AH plus sealer ‎using a dye penetration method. ‎ Materials and methods: ‎ Sixty single-rooted mandibular premolars were selected. The coronal ‎portion of each tooth was removed to standardize root length at 16 mm ‎and the root canals were prepared with NiTi rotary files (ProTaper Next) ‎up to X4 (40/0.06). Teeth were randomly assigned and divided ‎according to the sealer used for obturation into three groups of 20 each. ‎Group I: AH plus, Group 2: Nano calcium hydroxide and Group 3: ‎Nano-bioactive glass. All root canals were obturated using single cone ‎gutta-percha(#40/.06) and one of the tested sealers. Root canal sealing ‎was assessed by a dye penetration test. The data were statistically ‎analyzed by ANOVA test followed by post hoc analysis (P < 0.05).‎ Results:‎ Significant improvement shown by the presented study suggests that ‎nano calcium hydroxide sealer showed significantly less dye leakage ‎than nano bioactive glass sealers and Ah plus sealer.‎ Conclusion: ‎ The results of this study showed that the synthesized nano-powder ‎sealers are suitable for use in root canal therapy to prevent leakage.‎ The root canal can be sealed better by using smaller nano-powder ‎particle sizes. In addition, the two groups exhibited significant ‎differences in leakage in comparison with commonly used AH plus ‎sealer.‎

Aim: The aim of this study was to assess and draw comparisons between the antibacterial properties of various bioceramic sealers.Materials and methods: The samples were categorized according to the sealer type that was utilized. Group 1: Well Root ST, group 2: Ceraseal, group 3: Neosealer Flo, group 4: AH plus. Manufacturer's instructions were followed when preparing the sealers and placed in sterile plastic cylinders with a diameter and depth of 5 mm. Following that, specimens were incubated at 37°C and 100% humidity for 7 days. The bacterial suspension was made with a standardized density of 0.5 on the MacFarland (1.5x108/ml). The suspensions were diluted 10,000 times after mixing for six, fifteen, and sixty minutes, and then a triplicate amount of 0.01 from each diluted suspension was placed onto the pre-prepared BHI agar plates. (Difco Lab., Detroit, MI, USA). The number of colonies forming unit for each sealer was calculated in different time throughout the experiment. Results: For the effect on Enterococcus faecalis at 6 minutes, Neosealer Flo showed lowest bacterial count, at 15 minutes AH plus showed lowest bacterial count and 60 minutes Ceraseal showed lowest bacterial count. For the streptococcus mutans at 6 minutes, Neosealer flo showed lowest bacterial count, at 15 min AH plus and Well root ST showed lowest bacterial count and at 60 min well Root ST showed lowest bacterial count. Conclusion: All sealers showed antibacterial effect, where increasing the time resulted in decreasing Log10 CFU.

Objective: The aim of this study was to evaluate the effect of different concentrations of titanium dioxide nanoparticles on the mechanical properties of heat polymerized acrylic resin before and after thermocycling. The tested parameters were flexural strength and hardness Material and Methods: 120 specimens were prepared according to the specific dimension for each test (flexural strength and micro hardness) and distributed into - Before thermocycling (control, (TiO2) nanoparticles with concentration (0.1% and 0.2%) - After thermocycling (control, (TiO2) nanoparticles with concentration (0.1% and 0.2%) Thermal cycles were performed in a thermocycling machine consisted of 5000 cycles at 5°C and 55°C Results: Flexural strength and micro hardness were tested for both groups. The data was collected and statistically analyzed. Both Flexural strength and micro hardness were decreased by adding TiO2 nano particles concentrations. Conclusion: adding (TiO2) nanoparticles to methyl methacrylate adversely affects the flexural strength and micro hardness before and after thermocycling