Intraoral and transcutaneous photobiomodulation protocol for hyposalivation in head and neck cancer patients undergoing radiotherapy: a study protocol

Hyposalivation is a common complication in patients undergoing head and neck radiotherapy. It negatively affects quality of life and increases the risk of secondary conditions such as dental caries, opportunistic infections, and nutritional impairment. Photobiomodulation (PBM) has been proposed as a preventive strategy; however, there is no consensus regarding the optimal protocol or the most appropriate route of application. This pilot study aims to compare the efficacy of intraoral and transcutaneous PBM in preventing radiotherapy-induced hyposalivation. The intraoral protocol will use a 660 nm red laser (100 mW, 1 J, 10 s per point, 10.02 J/cm², total 44 points). The transcutaneous protocol will use an 808 nm infrared laser (100 mW, 1 J, 10 s per point, total 32 points). The intraoral approach will deliver targeted irradiation to oral tissues, while the transcutaneous approach will deliver infrared irradiation externally, taking advantage of its greater tissue penetration and potentially improved patient comfort. The primary outcome will be the incidence of stimulated salivary flow rate (salivary flow rate < 0.7 mL/min). Secondary outcomes will include patient-reported xerostomia and quality of life, assessed using validated instruments. This study will provide comparative data on two PBM delivery approaches for the prevention of radiotherapy-induced hyposalivation and may contribute to the optimization of clinical protocols in oncological care.