The goal of this clinical trial is to learn if high-level laser therapy can manage oral mucositis in pediatric patients undergoing hematopoietic bone marrow transplantation. The main question it aims to answer is :

Is high-level laser therapy effective as a treatment for oral mucositis in pediatric hemopoietic stem cell transplant patients? Researchers will compare patients receiving basic oral care to see the effect on the WHO oral mucositis scale.

Participants will be subjected to high level laser on lesion sites .

Inclusion Criteria:

• Children under the age of 18 years undergoing bone marrow transplantation during the phase of oral mucositis.
• Oral mucositis starting from grade II on the WHO scale for OM.
• Willingness to undergo treatment for four consecutive days and to return for evaluation 7 and 11 days after enrolment.

Exclusion Criteria:

• Previous treatment with photobiomodulation for oral mucositis.
• Limited mouth opening less than 2 cm.
• Presence of dysplastic oral lesions.
• Radiotherapy in the head and neck area.
• Vulnerable groups of patients or decision-impaired individuals as prisoners, handicapped and mentally retarded individuals