Single-session extraoral photobiomodulation reduces early postoperative pain but not edema or trismus after impacted mandibular third molar extraction: a randomized controlled trial

Postoperative pain, edema, and trismus are frequent complications following impacted mandibular third molar surgery. While photobiomodulation (PBM) is a proposed adjunctive therapy, clinical evidence remains controversial. This study evaluated the effects of single-session extraoral dual-wavelength PBM (650 + 904 nm) applied immediately after extraction on postoperative pain, edema, trismus, and quality of life (QoL). This prospective RCT enrolled 70 patients (mean age: 22.04 ± 2.61 years) with asymptomatic mesioangular impacted mandibular third molars (Pell-Gregory Class IB). Participants were randomized to a PBM (n = 35) or control (n = 35) group. Following standardized surgical extraction by a single surgeon, the PBM group received a 10-minute extraoral application (650 + 904 nm, GaAlAs laser). The primary outcome was postoperative pain, assessed by VAS on postoperative days 2 and 7. Secondary outcomes included QoL (VAS, days 2 and 7), edema (sum of three facial distances), and trismus (maximum interincisal distance), the latter two evaluated at baseline and on postoperative days 2 and 7. On postoperative day 2, pain VAS scores were significantly lower in the PBM group (20.34 ± 24.38 vs. 41.43 ± 25.15; p < 0.001) and QoL scores significantly higher (69.83 ± 25.87 vs. 50.51 ± 23.24; p = 0.002) compared to controls. By day 7, a statistically significant but clinically negligible between-group difference persisted in pain (Mann-Whitney U = 776.5, p = 0.040; mean difference 2.6 mm), while QoL no longer differed significantly between groups (p = 0.154). No significant between-group differences were observed for edema or trismus at any time point (p > 0.05). Single-session extraoral dual-wavelength PBM significantly reduces early postoperative pain and improves QoL on the second postoperative day following impacted third molar extraction, with no significant effect on edema or trismus. The clinically meaningful pain and QoL benefits resolved by day 7, and sham-controlled multi-session trials are warranted.