Levels of mutans streptococci and lactobacilli in plaque on aged restorations of an ion-releasing and a universal hybrid composite resin

The purpose of this in vivo study was to evaluate the cariogenic microflora of plaque on aged restorations of a hydroxyl, fluoride, and calcium ion-releasing composite resin (IRCR) (Ariston pHc), and to compare it intra-individually with a universal hybrid composite resin and enamel. Each of 19 subjects received one proximal restoration of the IRCR, one proximal universal hybrid composite resin restoration (CR) and each subject had one non-filled proximal enamel control surface to make intra-individual comparisons possible. To avoid peak ion releases from the materials, aged restorations were studied. Plaque was collected from 57 surfaces using sterile applicator tips. Samples were cultured to determine the numbers of mutans streptococci, lactobacilli, and total microorganisms. The relative numbers for mutans streptococci (% of total bacteria) were: IRCR 0.59%, CR 0.40%, enamel 0.22%. Two outliers were found in the IRCR group. Excluding these outliers resulted in a relative number of 0.33%. Lactobacilli were detected in the plaque from only 9 surfaces and at very low relative proportions for all three surfaces: 0.01%. The enamel surfaces showed the lowest relative numbers of mutans streptococci and lactobacilli, but the differences were not significant. It can be concluded that the ion release of the IRCR did not influence the growth of cariogenic microorganisms in dental plaque.