Guanidine hydrochloride polymer additive to undertake ultraconservative resin infiltrant against Streptococcus mutans

Abstract The S.mutans biofilm formation is an ongoing challenge for the long-term survival of dental resins. In this study, we report a strategy to endow antibacterial ability to resin infiltrants, a new and conservative class of material for microinvasive treatments. Polyhexamethylene guanidine hydrochloride was added at 0.5 or 1 wt%. One group without PHMGH was used as control. The antimicrobial performance of biointeractive dental resin infiltrant was evaluated against Streptococcus mutans planktonic cells and direct exposure biofilm models. The quality of the polymer was assessed by the degree of monomer conversion using Fourier-transform infrared spectroscopy. Data were analyzed by one-way ANOVA and Tukey (α = 0.05). The complete eradication of S. mutans biofilm was achieved when in contact with the resin infiltrants containing PHMGH at 1 wt% employed bactericidal and biofilm inhibition activity through a “contact–kill and release” mode of action. More importantly, the polyhexamethylene guanidine hydrochloride conveys biofilm inhibition to resin infiltrants while not adversely affect the critical physical properties of this material. This work may provide a simple pathway to develop antibacterial dental resin infiltrants.