Back ground: Oral lichen planus is a chronic inflammatory disease that affects the mucous membrane of the mouth. Several researchers suggest that oxidative stress is implicated in the pathogenesis of this disorder. It has been hypothesized that melatonin is powerful anti-oxidants and can easily cross the cell membrane and is considered a free radical scavenger of Hydroxid, Oxygen and Nitrogen dioxide, cortisol as a stress hormone and the immunoglobulin A as first line of defense and protection to the mucous membrane of the mouth are interrelated factors for the emergence of oral lichen planus. Aim of this study was to evaluate the level of melatonin, Cortisol and IgA in saliva of patients with oral lichen planus lesions in comparison with participants with normal oral mucosa. Materials and methods: In this study seventy five subjects with age 18 and over were included. The subjects were divided into two groups; control group, this group comprised of 41 subjects with normal oral mucosa and the study group, which comprised of 34 subjects with clinically and histopathologically diagnosed oral lichen planus lesion. The samples were selected from patients attending College of Dentistry/University of Baghdad and cases that recruited to the AL-Emmam Ali hospital / in Baghdad /Dermatology Department. Samples collection started from 2/ may 2013 to 23/ January 2014.Saliva samples were collected between 10-12 Am. High performance chromatography (HPLC) analyzing technique was used for estimating the salivary melatonin and cortisol level. IgA level was measured by ELIZA method. Results: The mean salivary melatonin level in patients with oral lichen planus was 4.786 µg/ml and the mean saliva melatonin level in normal person was 8.759 µg/ml. significant difference (p<0.01) was observed in the salivary melatonin levels between the study and control group. The mean salivary cortisol level in patients with OLP was 0.730 µg / ml and the mean saliva cortisol level in normal persons was 0.165 µg/ml. significant difference (p<0.01) was observed in the salivary cortisol levels between the study and control, group. The mean salivary IgA level in patients with OLP was 221.4 µg/ml and the mean saliva IgA level in normal person was 125.8 µg/ml. There was a high significant difference (p<0.01) the study and control groups. Conclusions: The level of salivary melatonin was lower in patients with oral lichen planus, however cortisol and IgA was higher when comparing the salivary level with that of the control groups.
