The prevalence of contact hypersensitivity in patients with oral lichen planus

Introduction
Oral lichen planus (OLP) is a chronic autoimmune inflammatory disease with an unknown aetiology and a higher prevalence in women. Oral lichenoid lesions both clinically and histologically resemble oral lichen planus and are often associated with contact allergy to dental materials. 
Aim: To investigate the prevalence of delayed hypersensitivity reactions in patients with OLP and to identify the most common allergens that may exacerbate the disease.

Material and methods
Twenty patients diagnosed with OLP and undergoing treatment in the Gerodontology and Oral Pathology Department of the Poznan University of Medical Sciences were enrolled in the study. The subjects underwent a detailed oral examination consisting of anamnesis and a clinical evaluation by a qualified dentist, while an assessment of the skin and skin appendages was carried out by a dermatologist. Patch testing was performed using the Polish Baseline Series and Dental Screening Series.

Results
 Fifty percent of the examined patients displayed positive patch test reactions. A total of 18 allergic reactions were revealed, but only four appeared during the first test. The most common allergens were found to be nickel, gold, and a fragrance mix. Only one patient had a positive reaction to more than three allergens. 

Conclusions
There seems to be a high contact reaction rate in patients with oral lichen planus, which is not related to contact with synthetic dental materials. However, further investigations on a larger population with the introduction of additional tests administered seven days after exposure are required to confirm the effects of delayed hypersensitivity reactions on patients with OLP exacerbation.