Photodynamic therapy of oral lichen planus

Oral lichen planus (OLP) is a chronic inflammatory and immune-mediated disease affecting the oral mucosa. OLP presents with asymptomatic, lacelike white stripes and/or symptomatic red, ulcerated mucous membranes. Eating, drinking and oral hygiene procedures may be painful resulting in reduced quality of life (QOL). The histopathological picture is a zone of cellular infiltrate, mainly CD8+ cells, in the superficial layer of the connective tissue and signs of liquefaction degeneration of the basal membrane. Conventional treatment is corticosteroids. Local and systemic side effects are common, and patients may develop drug resistance. The intention with this article is to demonstrate the heterogeneity in photodynamic therapy (PDT) of OLP. A search in PubMed, Embase (Ovid) and Medline (Ovid) identified seventeen clinical studies investigating PDT of OLP. Only five were randomised controlled studies and the study groups varied from 5 to 50 patients. Five different photosensitisers or precursors were tested. Both broadband spectrum lamps, lasers and light-emitting-diodes (LEDs), with wavelengths from 420 nm to 682 nm, were used. The number of treatment sessions varied from one to ten. The patients were followed up for 0 to 48 months, but in thirteen studies the post treatment observation time was ≤6 months. Single arm studies demonstrated improvement of OLP except in one study. In all controlled studies except for one, PDT was superior or equal to conventional treatment. The majority of patients experienced a slight burning sensation during light activation, but no serious adverse events were reported. Only few studies examined the effect of PDT on a cellular level.