Incorporation of Inorganic Antibacterial Agents into an Experimental Self-Etching Primer

Objectives: Developing antibacterial dental materials is a new direction for the improvement of caries control. This study was to compare the antibacterial activity and bond strength of an experimental self-etching primer (ESP) incorporating with different kinds of inorganic antibacterial agents, loading Ag/Cu/Zn or chlorite. Methods: Six inorganic agents (basic magnesium hypochlorite, Longbei inorganic antibiotic powder, Antim-AMS2, IONPURE-H, ZnO whisker antibacterial complex (ZnOw) AT-83, and ZnOw AT-88) were incorporated respectively into ESP, of which main components are maleic acid, 2-hydroxyethyl methacrylate (HEMA) and acetone. Broth microdilution susceptibility test and direct contact antibacterial test were performed against Streptococcus mutans ATCC 25175 to examine the antibacterial activity of primer at both unpolymerized and polymerized state. Enamel shear bond strengths were also tested. Results: The addition of Longbei inorganic antibiotic powder and ZnOw AT-83 at a concentration of 0.5% or 2.5% greatly decreased the Minimal Inhibitory/Bactericidal Concentration of ESP. Incorporation of ZnOw AT-83, Longbei inorganic antibiotic powder, Antim-AMS2, IONPURE-H at both concentrations significantly enhanced the antibacterial effect of ESP after being cured. Bond strengths didn't change statistically when the incorporation concentration of inorganic agents were 0.5%, while decreased greatly at a concentration of 2.5%. Conclusion: This study demonstrated, from the view of antibacterial activities, the preliminary feasibility of developing antibacterial self-etching primer by the incorporation of Longbei inorganic antibiotic powder or ZnOw AT-83 at a proper concentration, without adverse influence on bond strength.