Effects of polishing methods on adherence of Streptococcus sobrinus to composite resin-F2000

YANG Hong; SU Ling-yun; NI Long-xing

Abstract：AIM:To evaluate the effects of different polishing techniques on the adherence of Streptococcus sobrinus to surface of composite resin-F2000. METHODS:70 Composite resin-F2000 blocks (4 mm in diameter and 1 mm in thickness) were randomly divided into 5 groups and were polished for 10 s with polishing bur, polishing disc, polishing cup and polishing brush, respectively. Blocks with no polish served as controls. After polishing, the blocks were coated with fresh saliva and then placed into Streptococcus sobrinus suspensions. After 6 h and 24 h culture, the blocks were taken out and the bacteria attached to the surface were washed with 3 ml PBS ultrasonically. The OD value of the wash-out was measured. Furthermore, 1 ml of the wash-out was further plated on agar culture medium for 48 h to count the number of live bacterial. RESULTS:The number of attached bacteria increased in time dependently. The OD value and viable cells in polishing bur group is significantly higher than that of the control group ( P <0.05 ). However, the OD value and viable bacteria in polishing brush group is significantly lower than that of the control (P<0.05). There was no significant difference among the control, polishing disc and polishing cup groups. CONCLUSION :Polishing methods affect the adherence of bacteria to composite resin surface. The adherence of the polishing brush group was the least.