Photobiomodulation Delivery Parameters in Dentistry: An Evidence-Based Approach

Dosimetry at a level of 2-8 J/cm² at target cellular level has been accepted to represent the optimum range for the stimulatory benefits associated with photobiomodulation therapies. However, it has been proposed that a higher bracket of 10-30 J/cm² at target tissue level may represent a good and effective range for analgesia, accompanied by at-distance regional anti-inflammatory effects. However, although this provides a useful guideline, transforming recommendations into a translatable and repeatable clinical skill have to date proven elusive. Based on prior publications of systematic reviews by the authors, key factors have been identified, associated with reported clinical and in vitro and in vivo animal studies that can support outcome success or null responses. Drawn from five recently published systematic reviews, an analysis of an extended published evidence base indicates that research methodology should embrace a mature understanding of terminology, a requirement for consistent metered energy delivery, and an appreciation of optical transport techniques. Using models derived from orthodontics and oncology, evidence-based optimal delivery parameters and techniques are presented. Within the confines of the accepted inclusion criteria, a modified Cochrane risk of bias tool has been applied and the parameters extracted from the included studies were subjected to a meta-analysis. This demonstrated a low risk of bias from the studies included with a multivariate and/or univariate statistical analysis that supports the author's evidence-based determinations. The adoption of a surface optical spot size of >1 cm² demonstrated a high degree of success in managing both superficial as well as subsurface pathologies in oral care. Also, the timing of the intervention with conditioning before or at the same time as a potentially traumatic cellular event was found to be a significant signal of outcome success. An extended commentary explores the benefits and disadvantages of scanning techniques. The extracted clinical data are cross-referenced to the mechanisms suggested for photobiomodulation therapies from the authors' own current in vitro research, and proposals are made for some possible lines of approach in future research and clinical trials.