The effect of mouthwashes containing biguanides on dentin loss

Objective: This study analyzed the effect of biguanides (polyhexamethylene biguanide – PHMB and CHX) on dentin loss. The hypothesis tested was that the pre-treatment with 0.07% PHMB or 0.12% CHX would influence enzymatic degradation of the demineralized dentin matrix. Method: Seventy-two bovine dentin specimens were prepared and randomly divided into six groups. Nail varnish was applied on both sides of the surface of each sample to maintain a reference surface for wear determination. Specimens were cyclically de- and remineralized for six days. Demineralization was performed with a 0.87M citric acid solution (6x5min daily) in all groups. After demineralization, specimens were treated with distilled water (negative control), 0.12% CHX (positive control), 0.07% PHMB, Sanifill Premium^TM (0.07% PHMB plus 0.05% NaF), 0.15% Methylsilanol solution or F solution (0.05% F, as NaF). Specimens were kept in the treatment solutions for 1min, thoroughly rinsed, and then subjected to enzymatic challenge for 10min with bacterial collagenase (Clostridium hystoliticum, 100 µ/mL). Dentin loss was assessed after each day by profilometry (µm). Data were analyzed by 2-way RM-ANOVA and Bonferroni’s test (p<0.05). Results: In the first day, mean dentin loss ranged between 41.2 and 52.6 µm and no significant differences among the groups were observed. Dentin loss progressed significantly for all the groups along the six days of treatment. In day 6, the lowest mean (±SD) dentin loss was observed for Sanifill Premium^TM (94.3±3.9 µm), which significantly differ from all the other groups. PHMB and CHX led to intermediate dentin losses (129.4±41.2 and 135.3±33.5 µm, respectively) that were significantly lower than the values found for water (168.2±6.2 µm) and F (157.4±6.1 µm) that did not significantly differ from each other. Conclusions: Sanifill Premium^TM has good potential to prevent dentin loss which might be associated with the presence of PHMB and possibly other components present in the formulation.