Dentin-layer and photoactivation effects on antimicrobial potential of bonding systems

A new dentin bonding system (DBS) was recently launched with the aim of improving antimicrobial activity. Despite this potential, there are clinical factors that can reduce this effect. Objectives:The aim of this study is to access antimicrobial potential of Clearfil Protect Bond (CPB) compared to other commercially available DBS, considering clinical factors. Methods: CPB, Scotchbond multi-purpose (SBMP), Single Bond 2 (SB), Excite (E), Prime Bond NT (PBNT), Adhese (A), Xeno III (X) was tested. 0.12% Chlorexidine was used as a positive control. These products were evaluated in conjuction with Streptococcus mutans and Lactobacillus casei by using the pour plate method under different conditions: with or without light-curing (halogen device - 600mW/cm2) and with or without dentin disks interposition. Multi-step systems were individually evaluated. Products were placed on paper disks or 0.5mm dentin disks and placed onto agar culture, which were triplicated. After 48hours of incubation at 37ºC in an anaerobic condition, measurements (mm) of inhibition zones were calculated. Data was analyzed by ANOVA and Tukey test (p<0.05). Results: SBMP, PBNT, E, X and CPB inhibited S. mutans and CPB was the most effective one. CPB was the only system capable to inhibit L. casei. After light-curing, SBMP, PBNT, and CPB still inhibited S. mutans, although with a minor effect. Dentin disks were able to reduce antimicrobial effects of Clearfil Protect Bond, but did not stop the inhibition, regardless of the tested microorganism. Conclusion: Clearfil Protect Bond seems to be a promissory product on caries with regard to the recurrent prevention, once well-indicated. It showed antimicrobial effect even considering different microorganisms, photoactivation and dentin interposition.