Effect of Low-Level Laser Therapy on Trismus, Facial Swelling, and Pain Following Surgical Extraction of Impacted Lower Third Molars

Background: Light amplification by the stimulated emission of radiation (laser) is currently used as a therapy method for decreasing inflammation followed by oral surgeries. Therefore, the present study aimed at evaluating the effect of using diode low-power laser irradiation (photobiomodulation) on the amount of pain, swelling, and trismus due to latent mandibular third molar surgery (surgical removal of latent mandibular third molars). Methods: In this double-blind randomized clinical trial study, 16 individuals with latent mandibular third molars with an identical condition were selected. The teeth were randomly assigned to two groups of laser irradiated intervention group and a non-irradiated control group. A 940 nm diode laser with an output power of 200 mW and an energy density of 12 J/cm2 was applied for 60 seconds at a distance of 1 cm three intraoral points and an extraoral point. The distance between incisal edges of upper and lower central teeth, the horizontal distance between corners of lips and auricle (LE), the vertical distance between the outer canthus of the eye and the mandibular angle (EA), and pain visual analogue scale were measured before surgery and two and seven days after surgery. Results: There was no statistically significant difference between the two groups regarding EA and LE before intervention and on days 2 and 7 after intervention (P>0.05). However, the pain score was significantly higher before intervention (3.31±0.7 vs. 2.38±0.8, P=0.001) and on day 2 after intervention (6.5±1.32 vs. 4.5±0.97, P<0.001) in the control group. On day 7, a higher maximum jaw opening (MJO) was observed in the intervention group (40.68±5.76 vs. 36.81±4.35, P=0.04). Conclusions: Adjunctive diode laser photobiomodulation after third molar surgery was associated with a significant reduction in pain and trismus.