Inclusion Criteria:  Patients with malignant neoplasm in the oral cavity, pharynx or salivary glands.  The patient should receive a continuous course of radiation therapy (IMRT) with all of the following criteria applicable:  For a period of 3-7 weeks, 5-6 fractions per week. A minimum cumulative dose of 30Gy expected to cause OM (ORAL MUCOSITIS) by the third week. Or: Based on the clinical judgment of the Radiation Oncologist and BED2 ≥ 30 Gy The treatment field will include at least one oral site (buccal mucosa, floor of mouth, tongue, hard palate, retro-molar trigon, lips or oropharynx) With or without chemotherapy and / or immunotherapy at the same time. A patient with an ECOG PS functional status equal to or less than 2 Able to read and understand the informed consent form (ICF) and voluntarily provided informed consent The patient is able to undergo intra-oral treatments The patient is willing to perform the protocol.  Exclusion Criteria:  The patient underwent previous radiation to the current therapeutic field The patient has health conditions of the teeth or mouth that will prevent the application of intra-oral treatment The patient receives non-standard treatment for mucositis such as benzidamine, flipermine, etc. The patient is enrolled to any other clinical trial that includes treatment or intervention that may affect the course of mucositis. The patient has a diagnosis that affects the healing of wounds (eg diabetes, lupus, etc.) Pregnancy