Bacterial counts in carious dentine under restorations: 2-year in vivo effects

Little is known about the long-term effects of fluoride-releasing materials on carious dentine in vivo. The aim was to investigate the 2-year influenc e of a resin-modified glass ionomer cement (RM-GIC) and amalgam on the bact eriological counts of carious dentine that remained under class I restorati ons. To enable a split-mouth design, 33 molar pairs in 33 patients (mean ag e 15.1 years, SD 1.4) were selected, based on clinically and radiographical ly diagnosed occlusal dentine caries. The enamel of the carious molars was removed, and the carious dentine was sampled under aseptic conditions just beneath the dentinoenamel junction. The molars were alternately restored wi th RM-GIC or amalgam without further removal of carious dentine. The sample s were processed for microbiological determination of total viable counts ( TVC), mutans streptococci (MS), and lactobacilli (LB). The molar pairs of 2 5 patients were reevaluated after 2 years using the same clinical technique s and were permanently restored after complete caries removal. Both materia ls showed a substantial decrease in numbers of TVC and LB of the carious de ntine after the 2-year period. Compared to amalgam, the decrease in the num bers of LB was significantly more pronounced for RM-GIC. No microorganisms were detected in only 11 molars (6 RM-GIC and 5 amalgam] after the 2-year p eriod. Based on this study, we suggest that complete removal of carious den tine is still the best conservative treatment, irrespective of the restorat ive material used.