The present review summarises the effects of titanium tetrafluoride (TiF(4)) on the development and progression of carious and erosive lesions. The mode of action of TiF(4) is due to the formation of an acid-stable surface layer, which provides mechanical protection to the surface, and to an increased fluoride uptake, which might chemically reduce demineralisation of dental hard tissues. Most in vitro studies showed that TiF(4) is effective in reducing the formation of carious and erosive enamel and dentine lesions. Thereby, TiF(4) was equally or more effective than sodium fluoride (NaF), amine fluoride (AmF) or stannous fluoride (SnF(2)). While clinical data confirm the caries-preventive effect, clinical trials analysing the anti-erosive effect of TiF(4) are lacking. Few data available from in situ studies revealed conflicting results by showing either no effect or a beneficial effect of TiF(4) on enamel erosion. Even though research focused on TiF(4), there is also evidence to show that other metal fluorides, such as zirconium and hafnium tetrafluorides, affect enamel and dentine demineralisation. CONCLUSION: The potential of TiF(4) to prevent acid demineralisation requires further research to confirm the promising in vitro results obtained by in situ studies and clinical trials.