everal tissue interactions could be observed in oral tissues. At high power level, lasers can ablate and vaporize the tissues promoting not only the elimination or cut of a tissue but also to destroy bacteria. There is increasing popularity of high-power lasers for surgical debridement and antimicrobial therapy in the management of peri-implantitis and periodontal therapy. A recent method of low energy uses Er:YAG laser to contract oropharynx and decrease snoring. It would be necessary to evaluate the biological effect on fibroblasts and collagen to explain the mechanisms of this proposed treatment. The general objective is to understand the biological effect of Lasers in cells of lesions or diseases of the oral cavity. Our longterm goal is to explore the potential to use lasers in the treatment of several diseases of oral cavity. We will analyse the effect Laser in cells lines and evaluate proliferative markers, apoptotic markers and hypoxia markers. We will also perform a clinical prospective study of the use of Lasers groups of patients treated in CESPU Clinic. We will analyse the outcome in terms of recurrence/success of treatment or malignant transformation.