Monte Carlo simulation of light propagation in oral tissues for photobiomodulation therapy

Photobiomodulation (PBM) has emerged as a non-invasive approach for managing oral conditions such as oral mucositis, periodontal disease, and post-surgical wound healing. Despite encouraging clinical outcomes, no consensus exists regarding optimal PBM treatment protocols, particularly with respect to laser wavelength, power, and exposure time. A key barrier is the limited understanding of how light propagates through the heterogeneous and complex structures of the oral cavity. We utilize Monte Carlo (MC) simulations to model light propagation in oral tissues to better understand PBM dose distribution for dental and oral disease applications. Monte Carlo simulations were performed using both a simplified cubic geometry and a human head phantom. Our results demonstrate a significant angular dependence for 810nm light transport. Furthermore, the limited penetration depth—restricted to only a few millimeters of cortical tissue—suggests that transdermal delivery is insufficient for targeting the intraoral cavity, necessitating an internal light source for effective treatment. The results provide mechanistic insights into how light scattering and absorption govern therapeutic dose delivery in the oral cavity. These findings will contribute to the rational design of PBM protocols for oral diseases, supporting the establishment of standardized, evidence-based treatment parameters. Ultimately, this work aims to bridge the gap between clinical practice and biophysical modeling, enabling safer and more effective PBM therapy in dentistry.