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Introduction The denture bases fabricated from polymethylmethacrylate (PMMA) have some disadvantages, such as surface prone to microbial growth and biofilm accumulation, which contributes to the onset and dissemination of infections among denture wearers. Therefore, the purpose of this in vitro study was to evaluate the flexural strength, hardness, and antimicrobial effect of denture base resin incorporated with 0.05% and 0.1% silver nanoparticles (AgNPs) of Aloe barbadensis miller (aloe vera), Morinda citrifolia (noni), and Boesenbergia rotunda (finger root). Materials and methods A total of 84 PMMA samples were used and were divided into three groups. Flexural strength tests were performed on Group 1 PMMA blocks. Group 2 involved hardness testing of PMMA blocks, whereas Group 3 involved antimicrobial activity. Each group was subsequently split into seven subgroups with differing concentrations of AgNPs: Sub Group 1: control (no AgNPs), Sub Group 2: 0.05% aloe vera AgNPs, Sub Group 3: 0.1% aloe vera AgNPs, Sub Group 4: 0.05% noni AgNPs, Sub Group 5: 0.1% of noni AgNPs, Sub Group 6: 0.05% finger root AgNPs, and Sub Group 7: 0.1% finger root AgNPs. The flexural strength was evaluated using a universal testing machine (Instron 8801). Surface hardness was measured using a Vickers tester (Tukon 1102). For the antimicrobial activity analysis, the samples were incubated in a suitable culture broth containing Candida albicans for 24 hours. Microbial colony count (colony-forming unit (CFU)/mL) was estimated to evaluate the microbial adhesion to the surface of the denture base materials. Statistical analysis The flexural strength, hardness, and CFU between the groups were analyzed using one-way analysis of variance (ANOVA) followed by multiple comparisons with Tukey's honest significant difference (HSD) test (α=0.05). The level of statistical significance was determined at p<0.05. Results It was observed that the mean flexural strength was maximum in PMMA incorporated with 0.05% of aloe vera AgNPs and least in PMMA incorporated with 0.1% noni AgNPs. It was seen that a steady loss in flexural strength is observed from 0.05% to 0.1%. The mean hardness was maximum in PMMA incorporated with 0.1% of noni AgNPs and least in PMMA incorporated with 0.05% aloe vera AgNPs. It was also found that the hardness was directly proportional to the number of nanoparticles. With an increase in the weight percentage of nanoparticles, a steady increase in hardness was seen in all the test groups. In our study, the results showed that finger root 0.1% showed the least CFU with a significant reduction of C. albicans adherence; therefore, it indicates higher anti-fungal activity. Aloe vera 0.05% showed the lowest inhibition of C. albicans, suggesting the least anti-fungal activity. Conclusion Within the limitations of this study, It can thus be concluded that the addition of AgNPs incorporated with plant extracts of Aloe barbadensis miller (aloe vera), Morinda citrifolia (noni), and Boesenbergia rotunda (finger root) can alter the flexural strength, hardness, and microbial adhesion of PMMA. In our study, it can be concluded that flexural strength increases with the addition of AgNPs of 0.5% concentration after which a steady loss is seen. However, the hardness and antimicrobial activity increased with an increase in the concentration of AgNPs in all three plant extracts.
RESUMO
OBJECTIVE: The purpose of this in vitro study is to compare and evaluate the surface roughness and microbial adhesion of Staphylococcus aureus and Candida albicans after the finishing and polishing of three different denture base materials. MATERIALS AND METHODS: A total of 84 samples of three different denture materials were used. The samples were divided into three groups: Group I (conventional poly methyl methacrylate), Group II (injection-molded polymethyl methacrylate), and Group III (injection-molded polyamide). Fourteen samples from each group were tested for surface roughness using an optical profilometer. Seven samples from each group were incubated in a suitable culture broth containing Candida albicans and Staphylococcus aureus separately for 48 hours. Microbial colony forming unit (cfu/ml2) was estimated in order to evaluate the microbial adhesion to the surface of the denture base materials. Confocal laser scanning microscopy was done to visualize the microorganisms. RESULTS: The mean surface roughness of Group I was 0.1176± 0.04 µm, Group II was 0.0669±0.02 µm, Group III was 0.1971±0.02 µm. One-way ANOVA revealed statistically significant differences in the mean surface roughness values among the three groups (p < 0.05). Tukey HSD (honestly significant difference) test confirmed the specific differences within the groups. The results of colony forming unit showed maximum adherence in Group III samples among both the species followed by Group I samples and least in Group II samples. Confocal laser scanning microscopy revealed significant differences in microbial adhesion among both Staphylococcus aureus and Candida albicans in the three groups (p <0.05). One-way multivariate ANOVA was performed to analyze the data obtained from confocal laser scanning microscopy. Microbial adhesion was least observed in Group II samples followed by Group I samples and the highest microbial adhesion was observed in Group III samples. CONCLUSION: Microbial adhesion was proved to have a direct correlation with the surface roughness of denture base materials. An increase in surface roughness (Ra) increases microbial adhesion.
