Background: The present study was aimed to measure the salivary level of IL-17 in patients having atrophic and erosive Oral lichen planus lesions (OLP) and to evaluate the effect of topical corticosteroids used for treatment of erosive/atrophic oral lichen planus on the level of IL-17 in the saliva.

Subjects and methods: The present study was performed on 40 subjects divided into 3 groups Group (I) Twenty patients diagnosed with erosive/atrophic OLP received topical steroid (triamcinolone acetonide0.1%) four times per day for four weeks. Group (II) Ten patients diagnosed with reticular OLP and Group (III) Ten patients with normal mucosa (healthy control Group). Salivary samples were collected before and after treatment in group (I) and once from subjects in group (II) and (III) for determination of IL-17 levels using enzyme-linked immunosorbent assay (ELISA).

Results: The mean IL-17 levels in saliva of erosive/atrophic OLP group were statistically significantly higher before treatment with topical steroid than after treatment and both are statistically significantly higher than the reticular group and healthy control subjects. Also, the clinical score and pain visual analogue score values were statistically significantly higher in the erosive/atrophic group before treatment than after treatment.

Conclusions: The salivary levels of IL-17 in erosive/atrophic OLP patients was higher than the reticular OLP patients and both are higher than the healthy control subjects, suggesting that IL-17 has a major role in the pathogenesis of OLP and its salivary level may be diagnostic for the severity of the condition of the erosive/atrophic OLP.