ABSTRACT
Background: A major drawback of resin composites is their tendency to accumulate microbial biofilms that can lead to secondary caries. The objective of this study was to compare the mechanical properties and the degree of conversion of commercial resin-based composite materials containing a contact-killing antibacterial agent, dimethylaminohexadecyl methacrylate (DMAHDM), at different concentrations, with a fluoride-releasing composite material. Materials and methods: Four groups were tested: Tetric N Ceram composite material (G1), Tetric Evo Ceram (G2), and Tetric N Ceram with the addition of contact-killing antibacterial agent DMAHDM at concentrations of 3% (G3) and 5% (G4). The mechanical properties, including flexural strength, elastic modulus, and Vickers microhardness and the degree of conversion were investigated. Results: Adding 3 % and 5 % DMAHDM resulted in flexural strength values that were comparable to Tetric Evo Ceram. Tetric N Ceram was comparable to the group containing 3 % DMAHDM (p > 0.05). However, it was significantly greater when compared to Tetric Evo Ceram (93.3 ± 9.4) and 5 % DMAHDM (p < 0.05). Both the elastic modulus and Vickers microhardness values of Tetric N Ceram were significantly higher than those of the other groups (p < 0.05). Furthermore, the elastic modulus of Tetric Evo Ceram showed similar results to groups with 3 % and 5 % DMAHDM. Nevertheless, the Vickers microhardness value is significantly higher when compared to 5 % DMAHDM (0.394 ± 0.021) (p < 0.05) while it was comparable to that of 3 % DMAHDM (0.484 ± 0.016) (p > 0.05). There was no statistically significant difference in the degree of conversion between the groups (p > 0.05). Conclusion: Adding 3% DMAHDM to Tetric N Ceram resulted in flexural strength values that were similar to those of Tetric N Ceram and Tetric Evo Ceram. DMAHDM did not affect the degree of conversion of Tetric N Ceram composite.
ABSTRACT
PURPOSE: To compare the effect of polishing systems on surface roughness of nanohybrid and microhybrid resin composites. METHODS: Two types of restorative resin composites and two one-step polishing systems were used in this study (IPS Empress Direct as the nanohybrid resin composite and Filtek P90 as the microhybrid). A total of 120 discs were fabricated (n=120). The specimens were divided into six groups of n=20 each. For polishing systems, PoGo One-Step Diamond Micro-Polisher and OptraPol Next Generation were selected. The before and after mean Ra values were recorded using a surface profilometer. Results were statistically analyzed with the Kruskal-Wallis H and the Mann-Whitney U tests. A P-value of ≤0.05 was considered statistically significant. RESULTS: PoGo polishing system recorded the lowest surface roughness, in case of both nano and microhybrid composites, with mean Ra values of 0.060 µm and 0.108 µm, respectively. PoGo also produced maximum reduction in the surface roughness in the nanohybrid group with 56.83%. OptraPol recorded a comparatively similar mean Ra value of 0.067 µm for the nanohybrid composites but recorded the least reduction in surface roughness with 48.41% for the microhybrid group. CLINICAL SIGNIFICANCE: One-step diamond polishing systems combined with nanohybrid resin composites exhibit increased surface smoothness compared to microhybrids.
