Photodynamic treatment of oral lesions

Abstract

Photodynamic treatment (PDT) was first started in the oral cavity in the mid 1980s. Hematoporphyrins were rapidly replaced by Photofrin and meta-tetrahydroxyphenylchlorin (mTHPC) as photosensitisers of choice, and over the years these two have been approved by several health authorities for PDT. 5-aminolevulinic acid (ALA) and some dyes (e.g., toluidine and methyene blue) have also been tested. Several different nonthermal lasers have been used and lately light-emitting diodes (LEDs) have been tried. Most of the clinical treatments have been carried out on oral squamous cell carcinoma (OSSC), either primary or metastatic lesions, with good results. The treatment leaves little scarring and can be used before, in conjunction with, and adjunctive to other treatment modalities. The greatest disadvantage is that the patients are photosensitive for several weeks following systemic administration of the photosensitiser. PDT is now an accepted palliative treatment. Systemic administration of ALA has been more successful than local application in the treatment of precancerous lesions such as oral leukoplakia. PDT following topical application of photosensitiser (metylene blue and methyl-ALA) has shown improvement in cutaneous diseases of the oral mucous membrane such as oral lichen planus. The bactericidal effect of PDT has also been tested on oral plaque, but little clinical work has been performed so far. Instead of mechanical cleaning or antibiotic therapy, PDT may also play a role in dental diseases.