Effect of luting cement on dental biofilm composition and secondary caries around metallic restorations in situ.

Since the importance of luting cement on secondary caries in enamel and dentin is unknown, an in situ crossover study was conducted in three phases over 21 days using a fluoride-containing toothpaste. One hundred and twenty-six metallic restorations were cemented into the dentinoenamel junction of slabs of human teeth with zinc phosphate (ZP), resin-modified glass ionomer (GI) or resinous cement (RC). The slabs were inserted onto flanges of the removable partial acrylic dentures of 14 volunteers and covered with gauze to enhance dental plaque accumulation. The volunteers used fluoride toothpaste (1.100 microg F/g, w/w). After 21 days, the biofilm that formed on the slabs was collected for biochemical and microbiological analyses, and the demineralization in enamel-dentin around the restorations was evaluated. The fluoride concentration of biofilm in the GI group was higher (p<0.05) than the ZP and RC groups. Also, the concentration of Zinc in biofilm formed on the slabs cemented with ZP was higher (p<0.05) than the other groups. However, the effect of the luting material on enamel or dentin demineralization was not statistically significant (p>0.05). The data suggest that when fluoride toothpaste is used, the anticariogenic property of the luting cement may not be relevant to the reduction of secondary caries.

Effect of enzymatic and NaOCl treatments on acrylic roughness and on biofilm accumulation.

As denture cleansers should be able to reduce biofilm accumulation without changing the acrylic resin surface structure, this study evaluated the effect of denture cleansers on surface roughness of acrylic resin and on biofilm accumulation. It was conducted a crossover study of three phases of 4 days each and 13 volunteers wore palatal appliances containing four specimens of acrylic resin of known surface roughness which were extra-orally submitted once a day to three groups of separated treatments: (i) negative control, (ii) enzymatic commercial solution (Ortoform) or (iii) 0.5% sodium hypochlorite (NaOCl). The appliances were immersed eight times a day in a 20% sucrose solution to enhance biofilm formation. On morning of the fifth day of each phase, the amount of biofilm formed on the specimens was estimated by the amount of protein extracted with alkali and the surface roughness of the specimens was again measured. New palatal appliances with new specimens were worn by the volunteers in the following phases, but the treatments were changed. The roughness of the resin increased after the treatments (P < 0.05) but the difference among the cleansers was not statistically significant (P = 0.85). The lowest amount of biofilm formed on acrylic resin specimens was found for the treatment with NaOCl (P < 0.05) but the enzymatic product did not differ from the negative control group (P > 0.05). The data suggest that the roughness of acrylic resin was not changed by the cleansers, but the ability to reduce biofilm accumulation depended on the product used.