Comparison of the effects of TiF4 and NaF solutions at pH 1.2 and 3.5 on enamel erosion in vitro.

This study aimed to analyse and compare the protective effect of buffered (pH 3.5) and native (pH 1.2) TiF(4) in comparison with NaF solutions on enamel erosion. Bovine samples were pretreated with 1.50% TiF(4) or 2.02% NaF (both 0.48 M F) solutions, each at a pH of 1.2 and 3.5. The control group received no fluoride pretreatment. Twenty samples per group were eroded with HCl (pH 2.6) for 10 x 60 s. Erosion was either investigated by profilometry (n = 10) or by determination of calcium release into the acid (n = 10). Additionally, the elemental surface composition was quantified by X-ray energy-dispersive spectroscopy in fluoridated but not eroded samples (6 samples per group). Scanning electron microscopy was performed prior and after erosion (2 samples per group). Cumulative enamel loss (mum) and calcium release (nmol/mm(2)) were analysed by repeated-measures ANOVA. The Ti and F surface composition was analysed by one-way ANOVA separately for each element. Only TiF(4) at pH 1.2 reduced enamel surface loss significantly. Calcium release was significantly reduced by TiF(4) and NaF at pH 1.2, but not by the solutions at pH 3.5. Samples pretreated with TiF(4) at pH 1.2 showed a significant increase in Ti, while NaF increased F concentration significantly. Only TiF(4) at pH 1.2 induced the formation of a glaze-like layer, which was still present after erosion. Enamel erosion can be significantly reduced by TiF(4) at pH 1.2 but not at pH 3.5. TiF(4) at pH 1.2 was more effective in protecting against enamel erosion than NaF.