Antimicrobial photodynamic therapy-A discovery originating from the pre-antibiotic era in a novel periodontal therapy

- The major periopathogen, P. gingivalis, was proved very susceptible to photodynamic inactivation.
- aPDT promotes new bone formation in animals with induced periodontitis.
- It is controversial whether aPDT applied with SRP provides benefits in patients with periodontitis.
- aPDT reduces inflammation, as expressed by decreased bleeding scores, in periodontal patients.

Antimicrobial photodynamic therapy (aPDT) involves pathogens' destruction caused by means of toxic Reactive Oxygen Species (ROS) that are generated upon the interaction of a photoactivatable substance (photosensitizer), light of the appropriate wavelength and oxygen. Among many clinical applications, it is also used as a supplementary method of treatment of periodontal disease. Many in vitro studies confirmed, that a major periopathogenic bacterium, Porphyromonas gingivalis is susceptible to this method. Several animal model studies pointed, that even a single application of aPDT adjunctive to conventional scaling and root planning (SRP) promotes better tissue healing, reduces the inflammatory infiltrate and bone loss. The outcomes of clinical trials are, however, inconsistent. Although in several the superiority of combined treatment protocol (SRP + aPDT) over the conventional (SRP alone) was reported, it was not confirmed in other trials. Nonetheless, the reduction of bleeding indices favoring the combined therapy was observed in the majority of the studies. It indicates, that aPDT has an influence on the extent of inflammation and further studies are needed to establish an optimal protocol of treatment combining mechanical debridement with photochemotherapy in order to obtain good treatment outcomes in our patients.