Treating Oral Lichen Planus (OLP) is a big challenge for clinicians. Despite numerous existing remedies, to date no effective cure has been found, which is mainly attributed to the lack of understanding of the pathogenesis of the disease. The investigator's aim was comparing the effectiveness of topical steroids and diode laser in treating OLP patients. Twenty-four patients with OLP were allocated into two groups of twelve patients each. One group was treated with 970 nm diode laser applied twice weekly and the other group was treated with topical steroids applied four times per day. Patients were followed up for two months. Pain was recorded using the visual analog score (VAS) and the clinical signs and symptoms were recorded using the reticular, atrophic, erosive (RAE) sores. Pain and RAE records were taken before treatment, after treatment and after 2 months.

24 patients (16 females , 8 males ) were recruited in this study from the Dental Clinic of the National Research Centre, Egypt, and the Ethical Committee approved the study protocol. All patients were informed about the treatment plan and they all submitted a written informed consent before enrolment, which was carried out in accordance with the declaration of Helsinki. Inclusion criteria included oral lesions clinically and histopathologically consistent with the modifications for the WHO 2003 criteria suggested by van der Meij and van der Waal.13 Patients were excluded from the study in case of indefinite diagnosis (such as lichenoid inflammation); or those suffering from any disease that may present with features similar to OLP (graft versus host disease or lupus erythematosus),if they received any medication for OLP treatment in the two months prior enrolment in the study, if they were pregnant or lactating women, or if histological diagnosis revealed lichenoid changes or any signs of dysplasia. 4,14

Study design:

Patients were randomly divided into two groups using a randomization software, where a blocked randomization was used to ascertain equal distribution of patients into each group (parallel-group study).15 One group (12 patients) was irradiated with diode laser and the other group was treated with topical steroids. In the laser group, normal protective measures were taken, where patients and personnel wore laser safety glasses . OLP lesions were irradiated with a 970-nm diode laser (SIRO Laser Advance class III b, SIRONA, Germany) with a 2 W irradiation power in a continuous non-contact mode. The laser beam was delivered using a fiber-optic tip with a 320 µm diameter with defocused mode directed at the lesions plus 0.5 cm peri- lesional tissues with a slight overlapping in order to evenly distribute energy covering all the lesional and peri-lesional tissues until blanching of the area was observed.14 Diode laser was calibrated to an output power of 3W, frequency of 30 Hz, energy of 180 joule and time interval of 8 minutes divided into 4 sessions , two min each with one minute rest in between to allow for tissue relaxation.

Irradiation was done twice weekly (once every third day) for two months until the resolution of signs (meaning the resolution of all atrophic-erosive lesions, regardless of any persisting hyperkeratotic lesions) for a maximum of ten sessions.11 After each session, patients were advised to have a cold diet and use chlorhexidine oral gel postoperatively. The patients applied the gel twice a day to the lesion for one week.16 For the steroid group (12 patients), 0.1 % topical triamcinolone acetonide preparation (Kenacourt-A Orabase Pomad, DEVA HOLDINGS A.S., Istanbul, Turkey) was used where the patients' were instructed to apply the gel 4 times daily, with no food or fluid taken one hour after application. Patients used the medication for 4 weeks , and if extension of treatment was required after that period , patients were instructed to apply miconazole oral gel (JANSSEN-CILAG Pty Ltd 1-5 Khartoum Road North Ryde NSW 2113 Australia) four times a day for one week to protect from superimposed fungal infections.15 Scoring of the clinical signs was done according to the RAE (Reticular, Erosive, Atrophic ) scale of Thongprasom and co- workers.17 Total improvement of the clinical signs was given scores zero or one and was defined as the disappearance of all atrophic-erosive lesions, whether any hyperkeratotic lesions persisted or not. Partial improvement or persisting of the patient's condition meant a decrease (score 2, 3 or 4), or no improvement (no change in the patient's score). Hence the clinical and symptomatic improvement of the patient's lesion was expressed by the numerical difference between baseline and endpoint scores. 14 Pain was recorded using the Visual Analogue Scale (VAS), which consisted of a 10-cm horizontal line, starting from 0 (designating no pain experienced by the patient to 10 (designating unbearable or most severe pain). Pain and RAE records were taken before treatment, after treatment and then after 2 months follow up.

Inclusion Criteria:

• histological diagnosis of OLP on the basis of WHO criteria (Meji and van der Waal 2003).
• presence of painful and atrophic-erosive oral lesions, unresponsive to topical corticosteroid therapy
• ability to complete the present clinical trial.

Exclusion Criteria:

• Presence of histological signs of dysplasia
• use of lichenoid reaction inducing drugs
• Therapy for OLP in the 2 months prior to the study;
• Patients suffering from any disease that may present with features similar to OLP (graft versus host disease or lupus erythematosus)
• Pregnant or lactating females
• Patients with uncontrolled diabetes or hypertension, positive HCV Ab or HBs Ag.
• Smokers