In situ effect of fluoride from adhesive system and dentifrice on caries formation around restorations with gap in enamel and dentine

Secondary caries may be developed between tooth and restoration when marginal gaps are present, however this process could be inhibited by fluoride presence. This research had as the main objective to evaluate, in situ, through a randomized, split-mouth and double-blind, cross-over design, the influence of fluoride from self-etching adhesive systems or dentifrice on the secondary caries development on enamel and root dentine around composite resin restorations with or without marginal gaps. During two phases, of 14 days each, 16 volunteers wore intraoral palatal devices containing 4 human dental slabs composed by a portion of enamel and dentine, restored with Z-250 composite resin. The slabs were randomly divided among 8 experimental groups for each substrate (enamel and dentine) restored with one of the following adhesive: All Bond SETM (no fluoride - NFA) and One Up® Bond F Plus (fluoride - FA) with (G+) or without (G-) the presence of marginal gaps and the use of fluoride dentifrice (FD) or placebo (PD). The restoration procedures were made following the manufacturers instructions and the gap was induced with the use of metallic strips. Each volunteer was instructed to drop on the slabs a 20% sucrose solution 10x/day and use the standardized dentifrice 3x/day. By the end of each clinical phase, the dental slabs were removed and the biofilm was collected for total microorganisms, mutans streptococci and lactobacilli counting, as well as for analysis of fluoride quantity present. The mineral loss was analyzed by microhardness test in a longitudinal cut on enamel and dentine. The lesion depth and presence of the wall lesion were determined by polarized light microscopy. The results were analyzed by ANOVA, following a factorial delineation of 2x2x2. The fluoride from the adhesive did not provide any protection against secondary caries development for enamel and dentine and for none of the studied response variables (p > 0.05). The fluoride from the dentifrice showed a little protection for demineralization in dentin (p 0,05). O flúor do dentifrício mostrou leve proteção contra a desmineralização em dentina (p < 0,05). Houve uma maior presença de lesão de parede, tanto em esmalte quanto em dentina (p< 0,05), em restaurações com fenda independente da presença de flúor. No entanto, em restaurações com fenda, uma maior profundidade de lesão foi observada em dentina (p