SUMMARY Dentin hypersensitivity (DH) is related to an increase in dentin permeability. This study tested the effect of titanium tetrafluoride (TiF 4 ) compared with sodium fluoride (NaF) and potassium oxalate gel on reducing hydraulic conductance (Lp) from the perspective of diminishing dentin permeability. The Lp of the dentin disks (1.0 ± 0.2 mm) was evaluated using Flodec. The maximum Lp values of each disk were taken after phosphoric acid etching (15 seconds) and randomly allocated to seven groups (n=8) according to the treatments. The minimum (smear layer) and the maximum (after acid etching) Lp values were recorded. Treatments were performed for 4 minutes as follows: 1) NaF varnish 2) and solution (2.45% F, pH 5.0), 3) TiF 4 varnish and 4) solution (2.45% F, pH 1.0), 5) 3% potassium oxalate gel, 6) free fluoride varnish (placebo, pH 5.0), 7) and no treatment (control). The Lp after each treatment was assessed. Samples were exposed to an erosive challenge (6% citric acid, pH 2.1, 1 minute), and the final Lp was recorded. The data were statistically analyzed using repeated measures two-way analysis of variance ( p <0.05). All treatments were effective in reducing dentin Lp compared with the control immediately after the application. However, only potassium oxalate and NaF varnish significantly differed from placebo varnish ( p <0.0001). The same results were found after the erosive challenge. Therefore, the TiF 4 was less effective than the NaF varnish and potassium oxalate gel in reducing dentin permeability. Using this experimental model, both NaF varnish and potassium oxalate gel reduced the Lp similarly to the presence of smear layer.