Investigation of surface properties and bacterial adhesion of bulk-fill composite resins

Objective: This study aimed to investigate the effects of surface properties and elemental analysis of different bulk fill composites on bacterial adhesion. Method: In this study, Sonic Fill-2, Filtek Bulk Fill, Admira Fusion, Beautifil Bulk Restorative were used. Composite specimens were prepared (10x10x1 mm) and finishing and polishing procedures were applied with Sof-Lex discs. Glass was used as control material. Surface roughness (SR) was measured with profilometer. The hydrophobicity and SFE (Surface free energy) values of all test material surfaces was evaluated by measuring contact angles with computerized contact angle system. Elemental analysis of materials were performed. To produce pellicle, test specimens were covered with artificial saliva and mucin. Bacterial suspension was added to the pellicle-coated specimens. Bacterial suspensions were incubated at 37°C in 5% CO2 atmosphere for 24 hours. Adhered bacteria counts were determined as x108 ml Cfu/ml. Bacterial adhesion was investigated using confocal laser scanning microscopy. Statistical analysis was performed using the One-way ANOVA and Tukey HSD multiple comparisons (p=0.05). Results: The control group showed the lowest SR values.Statistically, there was no significant difference between the other groups except from the control materials. The lowest contact angle values were found in control group and Sonic Fill-2 while the highest SFE values were observed in these materials.The elemental contents of materials differed.There was no statistically significant difference between all values for S.Mutans.For S.Mitis adhesion, the highest value was found in Sonic Fill-2 and no significant differences was observed between the other groups. Conclusion: SR of bulk-fill composite resins had no effect on bacterial adhesion.However, it was observed that bacterial adhesion increased with the higher SFE values. The present study showed that bulk fill composite restoratives have similar susceptibility to adhere streptococci than to the control group. Key words: bulk-fill composite, bacterial adhesion, surface roughness, hydrophobicity