Effect of fluoride-resistant strains of Streptococcus mutans on the bonding strength of dental resin composite

Abstract

The aim of this study was to determine the influence of fluoride-resistant strains of S. mutans on the bonding strength of dental resin composite. Standardized specimens of resin composite (Z350), and self-etch adhesives (Single bond Universal, 3M) were incubated with S. mutans UA159, fluoride-resistant strains of S. mutans UA159 (UA159-FR) or uninoculated culture medium (Control) or PBS for up to 14 days. Resin-dentin bonded disks were subjected to push-out test. Fractured surface analysis of the specimens was performed by scanning electron microscopy(SEM). SPSS18.0 software package was used for statistical analysis. UA159-FR and UA159 were shown to decrease the bond strengths in levels comparable with those found in the control groups (P<0.05). SEM confirmed the increased degradation of all materials with UA159-FR and UA159, compared with control and PBS. The results suggest that resin-dentin interface can be compromised by oral bacteria that contribute to the progress of secondary caries. Fluoride-resistant strains of S. mutans and its parental strains both decrease bonding strengths in a short time, but no significant difference in the extent of damage.