The present review summarises the effects of titanium tetrafluoride (TiF4) on the development and progression of carious and erosive lesions. The mode of action of TiF4 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 TiF4 is effective in reducing the formation of carious and erosive enamel and dentine lesions. Thereby, TiF4 was equally or more effective than sodium fluoride (NaF), amine fluoride (AmF) or stannous fluoride (SnF2). While clinical data confirm the caries-preventive effect, clinical trials analysing the anti-erosive effect of TiF4 are lacking. Few data available from in situ studies revealed conflicting results by showing either no effect or a beneficial effect of TiF4 on enamel erosion. Even though research focused on TiF4, 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 TiF4 to prevent acid demineralisation requires further research to confirm the promising in vitro results obtained by in situ studies and clinical trials. Schlagwörter: caries, dentine, enamel, erosion, tetrafluoride