189 JCHR (2021) 11, 189-196 Journal of Chemical Health Risks www.jchr.org ORIGINAL ARTICLE The Efficiency of Photodynamic Therapy in the Management of Pain in Patients with Oral Lichen Planus Mona Abdallah Sabry *1 , Ali Mohamed Saafan 2 , Hanaa Mohamed El-Shennawy 3 , Amal Ali Hussine 4 , Doaa Mohamed Abd El- Aziz 5 , Doaa Ahmed Abdel Fadeel 6 1 Assistant Researcher, Surgery and Oral Medicine Department, National Research Center (NRC), Giza, Egypt 2 Professor of Dental Laser applications, National Institute of Laser Enhanced Sciences (NILES), Cairo University, Egypt 3 Professor of Oral & Dental Laser applications, Surgery and Oral Medicine department, National Research Center (NRC), Giza, Egypt 4 Associate professor of Oral Medicine & Periodontology, Faculty of Oral &Dental Medicine, Cairo University, Egypt 5 Associate professor of Chemical & Clinical Pathology, Faculty of Medicine, Ain Shams University, Egypt 6 Lecturer of Laser Applications in Pharmaceutical Sciences, National Institute of Laser Enhanced Sciences (NILES), Cairo University, Egypt (Received: 7 July 2021 Accepted: 15 September 2021) KEYWORDS Oral lichen planus; Pain; Photodynamic therapy ABSTRACT: Photodynamic therapy (PDT) which is a type of photochemotherapy is a new method of treatment used in cases of erosive/atrophic oral lichen planus (OLP) to reduce symptoms of the disease. Assessment of the effect of PDT on pain scale in patients having erosive / atrophic oral lichen planus.30 patients having erosive/atrophic OLP were recruited in this study. The oral lesions were subjected to PDT twice per week for 2 months. Methylene blue (MB) oral gel was used as a photosensitizer applied to the oral lesions, then diode laser of 650 nm WL and 150 mW (milli Watts) powers was used in a non- contact mode for 2:30 minutes. Visual analogue scale (VAS); pain scale was used for clinical assessment. The results showed improvement in the severity of pain over the duration of treatment. There was a gradual decrease of the mean VAS score over 8 weeks duration from 8±1 to 4±2. The decrease was statistically significant in the mean VAS score in the first month from 7±2 to reach 5±2 by the end of the second month (p<0.001). The use of photodynamic therapy was found to be effective in management of erosive / atrophic OLP; it showed improvement in the subjective as well as objective signs and symptoms of the disease with no side effects. INTRODUCTION Lichen planus is a chronic mucocutaneous autoimmune disease of unknown etiology. OLP is believed to be due to abnormal T- cell mediated immune response against the basal cell layer which was recognized foreign as a result of changes in the antigenicity of the cells [1]. Although the etiology of OLP is still unclear, there is evidence that it is a complex immunologic disease mediated by cytotoxic cells and directed against basilar keratinocytes and resulting in vacuolar degeneration and lysis of basal cells [2]. It affects skin, oral mucosa, genital mucosa, nails and scalps [3]. About 0.5- 2% of the populations are affected and females of the middle age commonly suffer from this disease [4]. Intraorally, the posterior buccal mucosa is most commonly affected, the *Corresponding author: sabry.mona@gmail.com (M. Abdallah Sabry) DOI: 10.22034/jchr.2021.686355