RESUMO
BACKGROUND: Pain from dental injections is a common reason why people fear dentistry and avoid dental treatment. Thus, researchers have attempted to find methods to decrease dental injection pain. OBJECTIVES: Considering the analgesic effect of the photobiomodulation therapy (PBMT), the aim of this study was to evaluate the effects of PBMT on the pain caused by dental anesthetic injections. MATERIAL AND METHODS: This randomized, split-mouth, triple-blind clinical trial evaluated 60 bilateral canine teeth in 30 dental students. After the random selection of the test (laser) quadrant, the injection site was irradiated with a 940 nm diode laser. Buccal infiltration anesthesia was then administered by injecting lidocaine plus epinephrine with a short needle. The level of pain experienced during the injection was determined using a 100-millimeter visual analog scale (VAS). The same procedure was performed for the control (no laser) quadrant, with the difference being that the laser handpiece was turned on, but no radiation was administered. The 2 groups were compared using the non-parametric Wilcoxon signed-rank test. RESULTS: The mean VAS pain scores were 21.2 ±15.7 for the laser quadrant and 27.9 ±18.9 for the control quadrant; this difference was statistically significant (p = 0.030), but did not seem to be clinically relevant. CONCLUSIONS: The photobiomodulation therapy prior to dental anesthetic injections has no clinical advantage for reducing injection pain.