The cytotoxic effect of TiF4 and NaF on fibroblasts is influenced by the experimental model, fluoride concentration and exposure time

Objective Titanium tetrafluoride (TiF 4 ) has shown promising effect in preventing tooth lesions. Therefore, we compared the cytotoxicity of TiF 4 with sodium fluoride (NaF) (already applied in Dentistry) considering different fluoride concentrations, pH values and experimental models. Materials and methods Step 1) NIH/3T3 fibroblasts were exposed to mediums containing NaF or TiF 4 (from 0.15 to 2.45% F), both at native and adjusted pH, for 6 h. Step 2) NIH/3T3 were exposed to NaF or TiF 4 varnishes with 0.95, 1.95 or 2.45% F (native pH), for 6, 12 or 24 h. We applied MTT (1 st and 2 nd steps) and Hoescht/PI stain (2 nd step) assays. Step 3) NIH/3T3 were exposed to NaF or TiF 4 varnish (2.45% F), at native pH, for 6 or 12 h. The cell stiffness was measured by atomic force microscopy (AFM). Results Step 1) All cells exposed to NaF or TiF 4 mediums died, regardless of the F concentration and pH. Step 2) Both varnishes, at 1.90 and 2.45% F, reduced cell viability by similar extents (33–86% at 6 h, 35–93% at 12 h, and 87–98% at 24 h) compared with control, regardless of the type of fluoride. Varnishes with 0.95% F did not differ from control. Step 3) TiF 4 and NaF reduced cell stiffness to a similar extent, but only TiF 4 differed from control at 6 h. Conclusions Based on the results of the 3 experimental steps, we conclude that TiF 4 and NaF have similar cytotoxicity. The cytotoxicity was dependent on F concentration and exposure time. This result gives support for testing the effect of TiF 4 varnish in vivo.