Photobiomodulation in Cells’ Repair

Abstract

Photobiomodulation is a non-invasive treatment modality acting at different biological levels through the non-thermal transfer
of photons to the living matter via a photoelectric effect, inducing photochemical reactions in treated cells. The objective of
this article is to review the literature on Photobiomodulation, its different fields of application and mechanisms of action, for
establishing a comprehensive summary of evidence. The search strategy initially run searches in scientific databases MEDLINE,
PubMed, EMBASE and Cochrane registries from 1990 up to March 2020, with entries Photobiomodulation, LLLT-LEDT, PDT,
Photobiology, Cytochrome c Oxidase. Selection criteria was based on preferably inclusion of randomized clinical trials (RCTs),
systematic reviews (SR) and studies providing qualitative and quantitative data with the best consistency, in a field where heterogeneity
of light parameters is often a difficulty to comparison of findings. Publised expert opinions were also considered. A total
of 80 publications were reviewed out of a thousand obtained from databases, among which were retained 9 RCTs, 6 systematic
reviews, 3 meta-analysis and 2 case-reports. Differences were found in treatment parameters as wavelength, dosage, energy output,
treatment length, performances of light-sources, quantity of diodes and single power of these, which may explain the paucity
of high-level body of evidence in Cochrane databases. However, numerous state-of-the- art researches are also found, led by
dedicated research teams paving the way to standardized methods of evaluation and comprehension of light-biological-tissues
interaction and optimization of outcomes in a promising field.