Effects of Infrared and Dual‐Wavelength Photobiomodulation Therapy on Mandibular Bone Healing Following Radiotherapy and Tooth Extraction: An Experimental Study

BACKGROUND: Osteoradionecrosis (ORN) is a serious complication of head and neck radiotherapy characterized by impaired bone healing. Infrared photobiomodulation therapy (IR-PBMT) and dual-wavelength photobiomodulation therapy (Dual-PBMT) have been proposed as non-invasive approaches to enhance bone regeneration. METHODS: Twenty-nine male Wistar-Albino rats were included. An experimental protocol designed to induce mandibular ORN was performed using a single 35 Gy radiation dose followed by mandibular molar extraction. Animals were allocated to four groups: control, radiotherapy plus extraction (RT + EX), RT + EX + IR-PBMT, and RT + EX + Dual-PBMT. IR-PBMT was performed using a 940 nm diode laser, whereas Dual-PBMT combined 632-650 nm red and 904-940 nm infrared wavelengths. Both PBMT protocols were applied extraorally for 14 consecutive days. Bone samples were evaluated histopathologically and immunohistochemically for alkaline phosphatase (ALP), bone morphogenetic protein-2 (BMP-2), osteonectin (ONC), and tartrate-resistant acid phosphatase (TRAP). RESULTS: The RT + EX group exhibited severe inflammation and tissue destruction, whereas both PBMT-treated groups showed reduced inflammation and partial epithelialization. Osteogenic marker expression was significantly lower and TRAP expression was significantly higher in the RT + EX group than in the control group (p < 0.05). Compared with the RT + EX group, both IR-PBMT and Dual-PBMT significantly increased ALP, BMP-2, and ONC expression and reduced TRAP expression (p < 0.05). ALP expression was significantly higher in the Dual-PBMT group than in the IR-PBMT group, whereas no significant differences between the two protocols were observed for BMP-2, ONC, or TRAP. CONCLUSION: Both IR-PBMT and Dual-PBMT improved the evaluated histological and bone-remodeling parameters following radiotherapy and tooth extraction. Because the control animals did not undergo tooth extraction, comparisons with the control group should be interpreted cautiously. Although Dual-PBMT produced a greater increase in ALP expression, the findings do not demonstrate the overall superiority of one PBMT protocol over the other. Both approaches may represent promising adjunctive strategies for mitigating radiation-associated impairment of mandibular bone healing.