The effectiveness of low-level laser therapy and low-intensity pulsed ultrasound in reducing pain induced by orthodontic separation: a randomized controlled trial.

Background: The low-level laser therapy (LLLT) and low-intensity pulsed ultrasound (LIPUS) have been recently applied to control pain during orthodontic treatment.

Objective: To evaluate and compare the effectiveness of LLLT and LIPUS in reducing pain induced by orthodontic separation.

Study Design: A single-blinded randomized controlled trial.

Methods: One hundred and fifty patients were randomly assigned into three groups; LLLT group, LIPUS group, and control group. After 5 min from the separators' placement, the first dose of the laser or the ultrasound was applied, the second dose was applied after 24 h, and the third dose was applied after 48 h on both maxillary and mandibular first molars. The exposure of laser was for 20 s at each point (maxillary and mandibular first molars), with an 810-nm aluminum-gallium-arsenide (AlGaAs) diode laser on continuous mode. The output power set at 150 mW, the energy density of 4 J/cm, and a laser spot diameter of 7 mm were applied. Whereas the frequency of ultrasonic toothbrush was 1.6 MHz; and average output intensity was 0.2 W/cm. The application was for 20 min (5 min on each first molar). The control group received the separators without another intervention. A Visual Analog Scale (VAS 100 mm) was used to assess pain intensity at several time intervals during the first four days after the separators' placement.

Results: A total of 145 patients were assessed. There was a significant difference in pain perception among the three groups after 5 min (P = .002). The maximum pain level was reached after 24 h. However, the laser group and the ultrasound group showed a statistically significant decrease in pain scores compared to the control group at all the assessment time points (P < .001). Whereas there was no difference between the laser group and the ultrasound group in reducing the pain scores (P > .05).

Conclusions: The LLLT and the LIPUS effectively reduce the separation pain when applied in multiple doses without differences between them.

Trial Registration: This trial was registered with the German Clinical Trials Register (DRKS). ( https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID= DRKS00029991). Date of registration: 26/08/2022.