In vitro enamel erosion and abrasion-inhibiting effect of different fluoride varnishes

To investigate the erosion and abrasion inhibiting effect of CPP-ACP/NaF and xylitol/NaF varnishes.

Bovine enamel samples (n=40) were exposed to the following treatments (n=10): NaF varnish (Duraphat^®, positive control); CPP-ACP/NaF varnish (MI varnishTM); xylitol/NaF (Profluorid^®) or distilled and deionized water (MilliQ^®, negative control). The samples were submitted for 3days to 4 cycles/day of erosion (5min in Sprite Zero) and 2 cycles of abrasion/day after the first and last erosive challenge, with a toothbrush machine and slurries of a placebo toothpaste for 15s (50 strokes/s). Among the cycles and after the last daily cycle, the specimens remained in artificial saliva. The change in the enamel surface was evaluated by using 3D non-contact optical profilometry with surface roughness (Ra and Sa values) and tooth structure loss (TSL) measurements. Scanning electron microscopy (SEM) assessed the enamel topographic characteristics. Differences in the Ra, Sa and TSL among treatments were tested using one-way ANOVA followed by the Tukey test.

All varnishes promoted better results for Ra and Sa values than the negative control (p=0.0001), without difference among them (p>0.05). However, CPP-ACP/NaF varnish stimulated fewer TSL (7.09±0.70μm) compared to NaF varnish (10.33±1.36μm, p=0.002), xylitol/NaF varnish (9.96±0.41μm, p=0.007) and the negative control (18.38±3.32μm, p=0.0001).

A single-application of fluoride topical varnishes was effective in reducing enamel wear. The CPP-ACP/NaF varnish had the best effect against enamel loss from an erosion-abrasion challenge.