Chapter 13: Photobiomodulation Therapy

INTRODUCTION

In recent years there has been significant interest in using light as a clinical therapeutic modality. This intervention provides the clinician with the potential of increasing or decreasing biochemical activity at any point during the healing cycle with few known contraindications. Terms such as phototherapy, biostimulation, photobiomodulation (PBM), and laser therapy are frequently used in the literature. Biostimulation has been determined not to be the best term as cellular inhibition can occur just as easily as cellular stimulation with the use of the light sources.⁸ The term soft laser was originally used to differentiate therapeutic lasers from hard lasers or surgical lasers. Several different designations then emerged, such as MID-laser (mid-infrared) and medical laser. Low-level laser therapy (LLLT) is another very common term that is used in the literature. There is some debate whether this name accurately depicts this light source as the term “low-level” can be very subjective.^25,33 In 2015 it was proposed that the term photobiomodulation be an all-encompassing term used to best describe nonthermal, nonionizing, light therapy including lasers (light amplification by stimulated emissions of radiation), light emitting diodes (LEDs), and broadband light that can create inhibiting or stimulating biochemical changes in tissues.^25,33 While those heavily involved in PBM research are trying to unify light therapy under one umbrella to avoid confusion, help guide future research, and accelerate the treatment’s acceptance, this chapter will still focus on specific forms of light therapy, namely LLLT, high-intensity laser therapy (HILT), and LED applications. Specifically, the chapter will reflect what is present in the literature, determine how similar and dissimilar the light sources are, and how to adopt different forms of PBM into clinical practice.

Einstein, in 1916, was the first to postulate the theorems that conceptualized the development of lasers. The first work with amplified electromagnetic radiation dealt with microwave amplification of stimulated emission of radiation (MASER). In 1955 Townes and Schawlow showed that it was possible to produce stimulated emission of microwaves beyond the optical region of the electromagnetic spectrum. This work with stimulated emission soon extended into the optical region of the electromagnetic spectrum, resulting in the development of devices called optical masers. The first working optical maser was constructed in 1960 by Theodore Maiman when he developed the synthetic ruby laser. Other types of lasers were devised shortly afterward. ...