Streptococcus mutans biofilm adhesion on composite resin surfaces after different finishing and polishing techniques

This study evaluated Streptococcus mutans biofilm adhesion on the surface of three composite resins (nanofilled, Filtek Z350, 3M ESPE, Salt Lake City, UT, USA; nanohybrid, Vit-1-escence, Ultradent Products, South Jordan, UT, USA; and microhybrid, Esthet X, Dentsply, Milford, DE, USA) following different finishing and polishing techniques. Sixty standardized samples (6 × 3 mm) of each composite were produced and randomly divided into three finishing and polishing treatments (n=20): 1) control group: composite resin surface in contact with Mylar matrix strips with no finishing or polishing performed, 2) Sof-Lex aluminum oxide disc technique (3M ESPE, and 3) carbide bur finishing and Astrobrush polishing technique (Ultradent). Half the samples of each group were incubated in human saliva for 1 hour, and all the samples were subjected to S mutans (ATCC 35688) biofilm development. The mean log of CFU/mL present in the S mutans biofilm was calculated, and data were statistically analyzed by three-way analysis of variance and the Tukey test (p<0.05). Human saliva incubation promoted a significant increase of bacterial adherence on all three of the composites' surfaces, regardless of the polishing treatment performed (p<0.05). Of the three, the nanofilled composite (Filtek Z350) had the lowest bacterial adherence with each of the finishing and polishing techniques despite the presence or absence of human saliva (p<0.05). Mylar matrix strips (control group) promoted the lowest bacterial adhesion on the surface of the microhybrid and nanofilled composites in the absence of human saliva.