Abstract: Objective: To evaluate the degree of polymerization, the long-term antibacterial, and bonding properties of resin adhesive containing silver nanoparticles. Methods: Silver 2-ethylhexanoate was added to 2-(tert-butylamino) ethyl methacrylate to form a 8 wt% silver salt containing solution. Then the mixed solution was added to the adhesive part of Clearfil SE Bond (CSB) to obtain three resin adhesives containing 0wt%, 0.10wt%, and 0.20wt% Ag. All specimens (diameter of 6 mm, thickness of 1 mm) were irradiated by 1000 mW/cm² for 20 s. Specimens were separately immersed in the sterile artificial saliva for 1 week and 12 weeks. The direct contact method was used to detect the antibacterial activity against Streptococcus mutans, and the formation of biofilms was observed by scanning electron microscope. The degree of conversion of specimens was measured by Fourier transform infrared spectrometer. And the micro-tensile bond strength of specimens was measured after soaking in artificial saliva for 1 d and 12 w. Results: There was no significant difference in the degree of conversion and micro-tensile bond strength above three resin adhesives (P>0.05). After immersion for 12 weeks, the 0 wt% Ag resin adhesive had no antibacterial ability, while the antibacterial rates of 0.10wt% Ag and 0.20wt% Ag adhesive were 87.00% and 93.48%, respectively. Conclusion: In-situ synthesis of silver nanoparticles could provide antibacterial properties for resin adhesives, and had no effect on the degree of conversion and bonding property of adhesives.

Key words: silver nanoparticles, resin adhesive, antibacterial activity, degree of conversion, microtensile strength