Effect of xylitol varnishes on remineralization of artificial enamel caries lesions in situ.

OBJECTIVES: Analyze the effect of varnishes containing xylitol compared to commercial fluoridated varnishes on the remineralization of artificial enamel caries lesions in situ. METHODS: Twenty subjects took part in this crossover, double-blind study performed in four phases of 5days each. Each subject worn palatal appliances containing four predemineralized bovine enamel specimens. Artificial caries lesions were produced by immersion in 30ml of lactic acid buffer containing 3mM CaCl2·2H2O, 3mM KH2PO4, 6µM tetraetil metil diphosphanate (pH 5.0) for 6days. The specimens in each subject were treated once with the following varnishes: 20% xylitol (experimental); Duofluorid™ (6% NaF, 6% CaF2), Duraphat™ (5% NaF, positive control) and placebo (no-F/xylitol, negative control). The varnishes were applied in a thin layer and removed after 6h. Fifteen subjects were able to finish all phases. The enamel alterations were quantified by surface hardness and transversal microradiography. The percentage of surface hardness recovery (%SHR), the integrated mineral loss and lesion depth were statistically analyzed by Friedmann and Dunn's tests test (p<0.05). RESULTS: Enamel surface remineralization was significantly increased by Duraphat™, Duofluorid™ and 20% xylitol formulations. Significant subsurface mineral remineralization could also be seen for the experimental and commercial varnishes, except for Duraphat™, when the parameter "lesion depth" was considered. CONCLUSIONS: 20% xylitol varnish seem to be a promising alternative to increase surface and subsurface remineralization of artificial caries lesions in situ. CLINICAL SIGNIFICANCE: effective vehicles are desirable for caries control. Xylitol varnishes seem to be promising alternatives to increase enamel remineralization in situ, which should be confirmed by clinical studies.

Inhibition of tooth erosion by milk containing different fluoride concentrations: an in vitro study.

OBJECTIVES: This in vitro study assessed the effect of milk containing different fluoride concentrations on tooth erosion. METHODS: Bovine enamel and root dentine specimens were treated with: (1) bovine whole milk with 0ppm F; (2) 2.5ppm F; (3) 5ppm F; (4) 10ppm F (all after erosion); (5) whole milk with 0ppm F (before erosion); (6) NaF (0.05% F, positive control, after erosion) or (7) 0.9% NaCl (negative control, after erosion). The specimens were submitted to pH cycles (4× 90s in soft drink) and treatments for 5 days. The specimens were immersed in the treatment solutions for 1min (only at the first cycle each day) with further exposition to 1:1 milk:saliva slurry for 10min. The tooth loss was measured using a contact profilometer and statistically analysed (p<0.05). RESULTS: Rinsing with milk before erosive challenge significantly reduced tooth loss compared to negative control (67% and 24% reduction in dentine and enamel loss, respectively) and to milk after erosive challenge, only for dentine. The addition of fluoride to milk also reduced tooth loss compared to negative control, but with no significant differences among fluoride concentrations for enamel and dentine (µm), respectively: 0ppm (3.63±0.04 and 2.51±0.53), 2.5ppm F (2.86±0.42 and 1.96±0.47), 5ppm F (2.81±0.27 and 1.77±0.44), 10ppm F (2.03±0.49 and 1.68±0.59). There was a negative and significant correlation between [F] and the tooth loss. CONCLUSIONS: Daily rinse with milk containing F is able to reduce both enamel and dentine erosion in vitro. CLINICAL SIGNIFICANCE: Since the prevalence of dental erosion is steadily increasing, rinse with milk or its derivate might be an important strategy to reduce the progression of tooth erosion.