During conditioning with chemotherapy and radiotherapy for the transplantation of hematopoietic stem cells (HSCT), oral changes, such as mucositis, xerostomia infections and dysgeusia may occur. Low level laser therapy is used to minimize the intensity of the lesions, prevent ulcerations in the mucosa, and diminish the time of healing. To verify the efficacy of low level laser therapy in the prevention of dysgeusia in patients undergoing allogenic HSCT and detect the frequency of dysgeusia, the flavors most changed, and the association of these changes with the clinical conditions of the patient. The study sample will be composed of 80 patients selected at the Hematopoietic Stem Cell Transplantation Center of the "Hospital Israelita Albert Einstein". The patients will be randomized and distributed into two groups: Placebo Group (n=40) - submitted to the routine laser therapy protocol in addition to simulated laser irradiation on the taste papillae; Test Group (n= 40) - submitted to the same laser therapy protocol as that of the Placebo Group, however, laser irradiation on the taste papillae will be effective. Daily intraoral exam will be performed in all the patients to evaluate mucositis, xerostomia and depapillation. The taste acuity test will determine the function of taste, using samples with the four basic flavors. This will be performed on the first day of conditioning (T0), during the stage of neutropenia (T1), at the time of discharge after transplantation (T2) and 100 days after transplantation (T3). A questionnaire will also be applied to evaluate the impact of changes in taste, smell and xerostomia on the quality of life. Our hypothesis is that the laser irradiation on the lingual papillae would help to prevent the changes in the cells of the taste papillae, preserving their morphology and function, which may attenuate the change in sense of taste and have a positive impact on the quality of life of patients during transplantation.

uring conditioning with chemotherapy and radiotherapy for the transplantation of hematopoietic stem cells (HSCT), oral changes, such as mucositis, xerostomia infections and dysgeusia may occur. Low level laser therapy is used to minimize the intensity of the lesions, prevent ulcerations in the mucosa, and diminish the time of healing. To verify the efficacy of low level laser therapy in the prevention of dysgeusia in patients undergoing allogenic HSCT and detect the frequency of dysgeusia, the flavors most changed, and the association of these changes with the clinical conditions of the patient. The study sample will be composed of 80 patients selected at the Hematopoietic Stem Cell Transplantation Center of the "Hospital Israelita Albert Einstein". The patients will be randomized and distributed into two groups: Placebo Group (n=40) - submitted to the routine laser therapy protocol in addition to simulated laser irradiation on the taste papillae; Test Group (n= 40) - submitted to the same laser therapy protocol as that of the Placebo Group, however, laser irradiation on the taste papillae will be effective. Daily intraoral exam will be performed in all the patients to evaluate mucositis, xerostomia and depapillation. The taste acuity test will determine the function of taste, using samples with the four basic flavors. This will be performed on the first day of conditioning (T0), during the stage of neutropenia (T1), at the time of discharge after transplantation (T2) and 100 days after transplantation (T3). A questionnaire will also be applied to evaluate the impact of changes in taste, smell and xerostomia on the quality of life. Our hypothesis is that the laser irradiation on the lingual papillae would help to prevent the changes in the cells of the taste papillae, preserving their morphology and function, which may attenuate the change in sense of taste and have a positive impact on the quality of life of patients during transplantation.

Inclusion Criteria:

• submitted a bone marrow transplantation
• adequate oral hygiene
• absence of periodontal disease and other infectious foci prior to transplantation
• normal chewing, swallowing and phonation functions prior to transplantation
• participation of all previously planned laser therapy sessions.

Exclusion Criteria:

• not performing all the steps of oral hygiene oriented during the transplant
• lack of collaboration in diagnostic test of the palate
• lack of records on dietary intake
• absence of record of clinical data of interest for the project in the medical record
• death during the transplant or 30 days after the completion of the bone marrow transplantation.

The patients will be randomized and distributed into two groups: Placebo Group (n=40) - submitted to the routine laser therapy protocol in addition to simulated laser irradiation on the taste papillae; Test Group (n= 40) - submitted to the same laser therapy protocol as that of the Placebo Group, however, laser irradiation on the taste papillae will be effective.