Efficacy of a novel at-home bleaching technique with carbamide peroxides modified by CPP-ACP and its effect on the microhardness of bleached enamel.

This study was designed to evaluate in vitro the efficacy of a novel at-home bleaching technique using 10% or 16% carbamide peroxide modified by casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and its influence on the microhardness of bleached enamel. A total of 40 bovine incisors were divided into four groups (n=10) according to the bleaching agent used: 10% carbamide peroxide only; a blend of 10% carbamide peroxide and a CPP-ACP paste; 16% carbamide peroxide only; and a blend of 16% carbamide peroxide and a CPP-ACP paste. During the 14-day bleaching regimen, the samples were stored in artificial saliva. The Vickers microhardness and color of the teeth were assessed at baseline (T0) and immediately after the bleaching regimen (T14) using a microhardness tester and a spectrophotometer, respectively. The degree of color change was determined by the Commission Internationale de l'Eclariage (CIE) L*a*b* system (ΔE, ΔL*, Δa*, and Δb*) and Vita shade guide parameters. The data were analyzed by analysis of variance and the Tukey test (p<0.05). The teeth that were bleached with a blend of peroxide (10% or 16%) and the CPP-ACP paste presented increased microhardness values at T14 compared with T0, whereas the samples that were bleached with peroxide only did not show any differences in their microhardness values. All of the bleaching agents were effective at whitening the teeth and did not show a statistically significant difference using the CIEL*a*b* system (ΔE, ΔL*, Δa*, and Δb*) or the Vita shade guide parameters. The use of a CPP-ACP paste with carbamide peroxide bleaching agents increased the bleached enamel's microhardness and did not have an influence on whitening efficacy.

Microbiota of dentinal caries as assessed by reverse-capture checkerboard analysis.

BACKGROUND/AIMS: This study aimed to identify the microbiota of different layers of dentinal caries by using a culture-independent molecular biology approach. METHODS: DNA was extracted from samples taken from 3 distinct layers (superficial, middle and deep) of advanced occlusal caries and analyzed for the presence and relative levels of 28 oral bacterial species/phylotypes using a reverse-capture checkerboard hybridization assay. RESULTS: The mean number of target taxa per layer was 7.7 (± 3.96) in the superficial, 7 (± 3.4) in the middle, and 6.3 (± 3.04) in the deep layer. No statistical significance was observed for these differences (p = 0.36). Overall, the most prevalent taxa in the 3 layers were Atopobium genomospecies C1 (72.5%), Fusobacterium nucleatum (69%), Lactobacillus casei (68%), Veillonella species (55%) and Lactobacillus fermentum (52%). No differences were found in the prevalence rates of the most frequent target species in the 3 layers. The most prevalent taxa found at levels above 10(5) in the advanced front line of deep-dentin caries were Atopobium genomospecies C1, F. nucleatum, Streptococcus mutans, Streptococcus species and Veillonella species. CONCLUSION: The present results revealed that the prevalences of several established or candidate caries pathogens do not differ significantly in the different zones of dentinal caries lesions. The finding that some as-yet-uncharacterized species and novel species were found in high frequencies join other molecular studies to include them in the set of candidate caries pathogens.