To evaluate the influence of a desensitizing agent (VivaSens) on efficacy of a paint-on bleaching agent (VivaStyle Paint On Plus). METHODS: Bleaching was performed for 7 days with VivaStyle Paint On Plus. The varnish was applied twice a day for 10 minutes each. 80 subjects were included in the study and randomly distributed in two groups (n = 40) according to exposed cervical dentin and perceived hypersensitivities. Group A used VivaStyle without VivaSens while Group B used VivaStyle Paint On Plus after a single application of VivaSens. Tooth color was assessed on facial surfaces of first upper incisors with Vita shade guide at baseline and 10 days after bleaching therapy. Sensitivity, with intensity graded from 0 (no sensitivity) to 10 (high sensitivity), was assessed chair-side using a blow of air at baseline, at the end of therapy (7 days) and 10 days after bleaching therapy. Statistical evaluation was performed with non parametric ANOVA. RESULTS: Thirteen subjects dropped out of the study; six due to gingival burning sensation (A: 3; B: 3) related to the bleaching regimen and seven due to lack of compliance. Directly after completion of bleaching therapy, tooth color had changed significantly compared to baseline in both treatment groups without difference among the groups. Color changes (Delta) according to Vita shade guide were as follows (mean +/- standard deviation): Group A: Delta 2.7 +/- 1.0, Group B: Delta 2.8 +/- 0.9. After bleaching (7 days) the intensity of tooth hypersensitivity (mean +/- standard deviation) was increased significantly compared to baseline in both groups (P < 0.05): Group A: 1.58 +/- 1.91 (baseline: 0.4 +/- 0.5); Group B: 1.3 +/- 1.8 (baseline: 0.5 +/- 0.7). The number of subjects reporting tooth hypersensitivity increased in Group A by 5 (n = 13) and in Group B by 1 (n = 10) subject. Although degree of hypersensitivities and number of subjects with hypersensitivities were lower in Group B, there was no significant difference between the groups.