Purpose: To compare single-application fluoride formulations on enamel erosion and erosion-abrasion in vitro. Materials and Methods: Enamel specimens were pretreated with either sodium, tin, titanium, or sodium/calcium fluoride and subjected to either an erosion model or an erosion-abrasion model, after which optical profilometry was used to measure enamel step height loss. Results: For erosion, the titanium fluoride (P .001) reduced enamel loss, whereas the calcium, tin, and sodium treatments showed no significant effects (P > .05). For erosion-abrasion, the titanium fluoride increased enamel loss in comparison to control (P .001). Conclusions: Titanium fluoride has differing effects on enamel loss from erosion and erosionabrasion models.