Effect of silver nanoparticles incorporation on impact strength of Heat-cure denture base resins

Background: Poly (Methyl methacrylic acid) based materials are widely used for the fabrication of removable complete and partial denture prostheses. these materials are prone to fractures when subjected to impact forces. While recent studies have explored the antimicrobial potential of denture base materials incorporating silver nanoparticles, their impact on the mechanical properties crucial for the prosthesis\u27s durability has not been adequately established. Aim: To evaluate the impact strength of the heat-cure denture base materials incorporated with various concentrations of silver nanoparticles.  Materials and Methods: Silver nanoparticles were incorporated at various concentrations (0.5, 1.0, 2.0 and 5.0 wt%) into three different heat-cure denture base materials. A total of 150 rectangular-shaped specimens (50 x 6 x 4), which comprises 50 samples from each of the three heat-cure acrylic resins were made using the compression molding technique. Ten specimens (n=10) were allocated for each concentration such as control, 0.5wt%, 1.0wt%, 2.0wt% and 5.0wt% concentrations of silver nanoparticles. A “V” notch was made exactly at the centre of each specimen to prevent the ductile fracture. The impact strength was evaluated using the Izod impact tester. The data were subjected to One-way ANOVA and Post hoc tests for statistical analyses. Results: A decrease in the impact strength was observed in the modified groups compared to the control groups. One-way ANOVA showed significant differences (p=0.000) among the different concentrations of all three denture base materials. Conclusion: Silver nanoparticles incorporation reduced the impact strength of the denture base materials

Effect of silver nanoparticles incorporation on microhardness of Heat-cure denture base resins

Background: Poly (Methyl methacrylic acid) based materials are widely used for the fabrication of removable complete and partial denture prosthesis. Regular cleansing of these dentures may abrade the surface due to an inherent lack of adequate surface hardness. This roughness may adhere food to the denture surface, making it dirty and further cause stomatitis. Recently, antimicrobial activity of denture base materials incorporated with silver nanoparticles was studied, that may logically prevent microbial growth on the denture. However, the effect of these nanoparticles on the mechanical properties, which provide longevity to the prosthesis, was not substantiated.  Aim: This study was designed to evaluate the effect of incorporating various concentrations of silver nanoparticles into heat-cure denture base resin materials, on their surface hardness.  Materials and methods: Silver nanoparticles were incorporated at various concentrations (0.5, 1.0, 2.0 and 5.0 wt%) into three different heat-cure denture base materials. A total of 150 rectangular-shaped specimens (62 x 10 x 2.5), which comprises 50 samples from each of the three heat-cure acrylic resins were made using the compression moulding technique. Ten specimens (n=10) were allocated for each concentration such as control, 0.5wt%, 1.0wt%, 2.0wt% and 5.0wt% concentrations of silver nanoparticles. The microhardness was evaluated using the Vickers micro-hardness tester. The data were subjected to One way ANOVA and Tukey HSD tests for statistical analyses. Results: Significant differences (p=0.000) were observed between the unmodified and modified denture base materials.  Conclusion: Silver nanoparticles can be considered as the favourable additives to increase the surface hardness of denture base materials

Machining Performance of AA2024/5Al2O3/5Gr Hybrid Composites under Al2O3 Mixed Dielectric Medium

In this research work, AA2024/5Al2O3/5Gr hybrid composites fabricated through stir casting were machined utilising an electric discharge machine (EDM). Experiments were performed by varying current, pulse on time (POT), gap voltage (GV), and Al2O3 powder concentration (PC). The experiments were designed using response surface methodology in which material removal rate (MRR), tool wear rate (TWR), and surface roughness (Ra) were recorded as responses. The addition of Al2O3 particles has a positive impact on MRR and Ra, whereas it has a negative impact on TWR. The interaction impact of process parameters (p-p) on responses was thoroughly analyzed using contour plots. A mathematical model was developed and validated for all the responses. The experimental results were compared with the predicted values. It was found that all the values have a maximum deviation of 3.5%. The ANOVA table reveals that the PC was the most influential factor followed by the current