Methods: One hundred disc-shaped specimens (6 mm in diameter, 2 mm in thickness) were made using five different dental restorative composite materials (Filtek Silorane and Filtek SupremeXT, 3M ESPE; CeramX Duo, Dentsply; Venus, Heraeus; Tetric EvoCeram, Ivoclar Vivadent). The samples were light cured with a halogen lamp (1000 mW/cm2 ) for 40 seconds in oxygen-free conditions below a glass slide device to prevent roughness, then sterilized by means of a UV-lamp.
Specimens for each material were divided in 5 groups, then incubated for 2, 4, 6, 24 and 48 h at 37 °C with Streptococcus mutans NCTC 10449 and processed to extract DNA from the bacteria adhered to the surfaces. Real-time PCR amplification was performed. Using a standard quantitative curve based on serial dilutions of a specific recombinant plasmid, the S. mutans concentration on each sample surface was calculated, considering a latency phase (2 to 4 h) and a growth phase (6 to 48 h).
The inter and intra group results were analysed with ANOVA statistic method.
Results: No significant difference was found in the overall performance of the tested materials after 48 h (p>0,05), with remarkable bacterial concentration on all samples. In the bacterial adhesion phase (2 to 4 h), Filtek Silorane showed the lowest grade of adhesivity (64,04%). In the 6 to 48 h time frame, Tetric EvoCeram showed the lowest S. Mutans percentual growth.
Conclusion: S. mutans may grow on all composite material surfaces. At the same time we observed that Filtek Silorane seems to prevent the initial bacterial adhesion compared to other composite materials.