Effect of photobiomodulation with low-level laser therapy combined with potassium nitrate on controlling...

To evaluate the effect of photobiomodulation with low-level laser therapy (PBM-LLLT) combined with 5% potassium nitrate (KNO₃) on controlling tooth sensitivity (TS) after in-office tooth bleaching.

Fifty volunteers were selected based on the inclusion and exclusion criteria and were randomly allocated into four groups: G1 (control): placebo gel application, 35% hydrogen peroxide bleaching (HP35) and mock PBM-LLLT without light emission; G2: placebo gel application, bleaching with HP35 and PBM-LLLT; G3: application of KNO₃, bleaching with HP35 and mock PBM-LLLT; and G4: application of KNO₃, bleaching with HP35 and PBM-LLLT. A pain assessment questionnaire was used to evaluate TS during the 21 days of treatment. The Friedman test was used for intragroup analysis, and the Wilcoxon and Mann-Whitney tests were used for intergroup comparisons.

The intragroup evaluation showed significant differences among the evaluation times in all groups (p ≤ 0.05). The highest pain sensitivity levels were recorded on the 1st, 8th, and 15th days. In G1, TS manifested for up to 3 days after each bleaching session, while G2, G3, and G4 presented TS only on the days of the bleaching sessions. Intergroup analysis showed that TS manifestation differed significantly between G1 and the other groups (p ≤ 0.05) but did not differ significantly among G2, G3, and G4 (p ≥ 0.05).

PBM-LLLT and KNO₃ are effective at reducing pain sensitivity after tooth bleaching, but no synergistic effect between these treatments was observed for the different evaluation periods.

The effect of PBM-LLLT combined with KNO₃ on post-bleaching tooth sensitivity is similar to their individual use alone.