Purpose: To assess the effectiveness of four in-office therapies used for the treatment of dentin hypersensitiviy (DH) after one single application. Materials and Methods: A randomised, controlled, split-mouth clinical trial was designed to evaluate the following treatments: 5% sodium fluoride varnish (positive control); 3% potassium oxalate; two-step self-etching adhesive; high power diode laser. Nineteen patients were selected and one tooth per quadrant was included in the study. After evaporative stimulation, pain was quantified by the Visual Analog Scale (VAS) at baseline, immediately after treatment, and after 15, 30 and 60 days. Results: Compared to the baseline values, fluoride varnish (p = 0.00) and potassium oxalate (p = 0.00) presented an immediate desensitising effect that remained constant at 15, 30 and 60 days. The high-power diode laser presented significant reduction in VAS scores after 15 days (p = 0.00), while in the self-etching adhesive group, a significant reduction in VAS scores was observed only after 60 days (p = 0.03). The change in VAS ([VAS x days] - VAS baseline) differed among the groups immediately after treatment, being higher in the fluoride varnish and lower in the adhesive groups, but no statistically significant difference was found at time intervals of 15, 30 and 60 days. Conclusion: When an immediate desensitising effect is desired after one single application, fluoride varnish and potassium oxalate should be used. High-power diode laser and self-etching adhesive may not be clinically considered an appropriate desensitising therapy after one single application. Keywords: dentinal desensitisers, dentin hypersensitivity, dentin permeability, diode lasers