Effects of a dental adhesive incorporating antibacterial monomer on the growth, adherence and membrane integrity of Streptococcus mutans

Objectives: This study was attempted to incorporate an antibacterial monomer, methacryloxylethyl cetyl dimethyl ammonium chloride (DMAE-CB), into a commercial dental adhesive and to evaluate the antibacterial activity of the DMAE-CB-incorporated adhesive after being cured against Streptococcus mutans. Methods: DMAE-CB was incorporated at 3% (w/v) into a clinically used dental adhesive, Single Bond 2. Single Bond 2 without DMAE-CB was served as a negative control; Clearfil Protect Bond, containing an intensively researched antibacterial monomer MDPB, was enrolled as a positive control. The effects of the cured adhesives and their eluents on the growth of S. mutans were determined by film contact test and absorbance measurement, respectively. The effects of the cured adhesives on the adherence and membrane integrity of S. mutans were investigated using confocal laser scanning microscopy (CLSM) in conjunction with fluorescent indicators. Results: Compared with negative control, the cured DMAE-CB-incorporated dental adhesive and positive control were found to exhibit inhibitory effect on the growth of S. mutans (P < 0.05), whereas their eluents did not show detectable antibacterial activity. Moreover, the fluorescence analysis of CLSM images demonstrated that the cured DMAE-CB-incorporated adhesive and positive control could hamper the adherence of S. mutans and exert detrimental effect on bacterial membrane integrity (P < 0.05). Conclusions: The incorporation of DMAE-CB can render dental adhesive with contact antibacterial activity after polymerization via influencing the growth, adherence and membrane integrity of S. mutans. (C) 2008 Elsevier Ltd. All rights reserved.