Evaluation of relationship between surface roughness and biofilm formation on silorane-based composite resin after bleaching with different strategies

Abstract

The main problem of resin composites is polymerization shrinkage which leads to leakage and secondary caries and to reduce this problem resin composites with the base of silorane has been introduced. Various studies have been evaluated the effect of bleaching on the surface roughness and biofilm formation of restorative materials, but none of them have been studied the effect of bleaching on the surface roughness and biofilm formation of composites with the base of silorane. This study was aimed to evaluate the effect of different bleaching strategies on the surface roughness and biofilm formation of composites with the base of silorane. Methods and materials: 60 samples of resin composites with the base of silorane (thickness of 3mm and diameter of 6mm) were prepared in the cylindrical acrylic molds. All samples were polished with aluminum oxides disks. Samples were divided into 4 groups (n=15) randomly. The samples of group 1 were stored in distilled water for control group. The samples of groups 2, 3 and 4 were bleached using 15% carbamide peroxide, 35% hydrogen peroxide and 35% hydrogen peroxide activated by photo. Then surface roughness of control and bleached groups were measured by profilometer. The streptococcus mutans which had been cultured in the BHI was used to evaluate the biofilm formation on the samples of 4 groups and pure plate technique was used to colony count. The data related to surface roughness and biofilm formation was analyzed with one way ANOVA and suitable post-hoc test. Regression model test was used to determine the relationship between surface roughness and biofilm formation. Results: The results of this study showed that biofilm formation of groups with surface roughness of <1?m, 0.6-0.9 ?m and equal or more than 1 ?m were 7326.4 103 cfu/ml, 8200 103 cfu/ml and 7317.3 103 cfu/ml, respectively. Statistical analysis with one way ANOVA showed significant difference in the biofilm formation according to the surface roughness. The results of Tukey test also showed that biofilm formation in samples with surface roughness of 0.6-0.9 ?m were significantly more than surface roughness of <1 ?m (P<0.05) and samples with surface roughness of equal or more than 1 ?m (P<0.05). Conclusions: According to the results of this study we concluded that there was a significant difference in the biofilm formation according to the surface roughnes of resin composites with the base of silorane after bleaching process with different agents.