Surface degradation and biofilm formation on hybrid and nanohybrid composites after immersion in different liquids.

PURPOSE: This study evaluated the association of surface degradation and formation of Streptococcus mutans (S. mutans) biofilm in resin-based composites (RBCs) after storage in different acidic liquids. METHODS: To evaluate microhardness and surface micromorphology, hybrid and nanohybrid RBC discs were stored in artificial gastric acid, cola drink, orange juice, artificial saliva, and distilled water for three intervals of 15 min per day for 7, 15, and 30 days. After 30 days of storage, surface roughness was analyzed, and the RBC discs were placed in a biofilm reactor inoculated with S. mutans to evaluate surface biofilm formation. RESULTS: As compared with nanohybrid RBCs, roughness and surface microhardness values were significantly lower (P < 0.05) for hybrid RBCs stored in artificial gastric acid, followed by specimens stored in cola drink and orange juice. Artificial gastric acid caused greater surface degradation, which increased the biomass of S. mutans on the surface of both RBC types. CONCLUSION: Surface degradation of hybrid and nanohybrid RBCs correlated with the pH of the liquid, while S. mutans biofilm formation was associated with increased surface roughness in hybrid RBCs.

Effect of dental restorative materials surface roughness on the in vitro biofilm formation of Streptococcus mutans biofilm.

PURPOSE: To evaluate Streptococcus mutans biofilm formation over different restorative dental materials. METHODS: Using a bioreactor over 72 hours, four commercially available ceramics were evaluated: IPS E-max Press, IPS E-max CAD, Lava Ultimate CAD-CAM, Vita Enamic and two resin composites (SR Nexco Paste and Brilliant NG). The results were evaluated using atomic force microscopy and confocal microscopy, the biofilm was stained and the arbitrary fluorescence units (AFU) quantified. RESULTS: The results showed that IPS E-max CAD had the lowest roughness values (4.29±1.79 nm), while the highest values were observed for Vita Enamic discs ( (77.13±17.35 nm). Analysis of S. mutans biofilm formation by AFU revealed lower values for IPS E-max CAD (6.77±1.67 nm); the highest values were found for Lava Ultimate (79.99±22.23 nm). Regarding the composite groups, SR Nexco Paste showed roughness values of 15.07±2.77 nm and lower arbitrary fluorescence units of 30.92±12.01 nm than Brilliant NT. There was a correlation between the surface roughness of ceramics and composite with S. mutans biofilm formation. CLINICAL SIGNIFICANCE: The adhesion of oral bacteria to restorative dental materials plays a key role in the success of dental treatment; the surface roughness influences the S. mutans biofilm formation.