The application of antimicrobial photodynamic therapy (aPDT) in dentistry: a critical review

Abstract

In recent years there have been an increasing number of in vitro and in vivo studies that show positive results regarding antimicrobial photodynamic therapy (aPDT) used in dentistry. These include applications in periodontics, endodontics, and mucosal infections caused by bacteria present as biofilms. Antimicrobial photodynamic therapy is a therapy based on the combination of a non-toxic photosensitizer (PS) and appropriate wavelength visible light, which in the presence of oxygen is activated to produce reactive oxygen species (ROS). ROS induce a series of photochemical and biological events that cause irreversible damage leading to the death of microorganisms. Many light-absorbing dyes have been mentioned as potential PS for aPDT and different wavelengths have been tested. However, there is no consensus on a standard protocol yet. Thus, the goal of this review was to summarize the results of research on aPDT in dentistry using the PubMed database focusing on recent studies of the effectiveness aPDT in decreasing microorganisms and microbial biofilms, and also to describe aPDT effects, mechanisms of action and applications.

Keywords: bacteria; biofilms; photochemotherapy; photosensitizing agents.

Figures

Figure 1

Mechanism of PDT. The photosensitizer is absorbed by the microorganisms and following exposure to light under an appropriate wavelength it becomes activated to an excited state. Then, the photosensitizer transfers energy from light to molecular oxygen to generate singlet oxygen and free radicals that are cytotoxic to cells.

Figure 2

Morphological structure of bacteria: Gram-positive and Gram-negative.

Figure 3

Scheme of laser operation.

Figure 4

Scheme of LED operation.