The purpose of this study is to evaluate the effectiveness of using to low intensity laser as an intervention against preventive and therapeutic oral mucositis induced by radiotherapy and chemotherapy.

Inclusion Criteria:

• Patients diagnosed with squamous cell carcinoma of the oral cavity.
• Patients aged between 18 and 80 years.
• Patients who are to receive one of the following treatment
• Combined radiotherapy (conventional fractionation 70 Gy reaching the tumor and affected lymph nodes, and 50 Gy in the areas ganglion drainage) and chemotherapy (cisplatin 100 mg/m2 IV on days 1, 22 and 43 irradiation or cetuximab 400mg/m2 as a single dose pre-load radiotherapy and 250mg/m2 weekly for the same. Regardless of whether they have received previous surgical treatment.
• Treatment with radiotherapy of 70 Gy in 35 daily sessions 2Gy/día consecutive.
• Patients who voluntarily express their intention to participate by informed consent.

Exclusion Criteria:

• Patients who denied informed consent.
• Patients who have hypersensitivity or allergy to any of the components included in the study.
• Patients diagnosed with HIV, and autoimmune diseases.