This is a one year prospective two arm parallel randomised controlled trial design.Patient’ll be recruited from the OPD (Out Patient Department) of department of Radiation oncology of Acharya Harihar Post Graduate Institute of Cancer (AHPGIC),Cuttack.Patients with head and neck cancer who are planning for/undergoing RT with more than 50Gy of radiation, with or without chemotherapy, those whose oral cavity lies within the RT field during treatment, 21 years of age or older, having at least two remaining teeth after oral health clearance, having no known milk allergy and who are able to give informed consent will be included in the study.Patients who have received RT previously or receiving RT for palliative care,  those with edentulous upper and lower jaws and those with a habit of mouth breathing will be excluded from the study. Information regarding the socio demographic profile, tumor location, staging, histopathology, radiation dosage, and surgery, oral hygiene habits, relevant medical history, dental history, baseline recordings and follow up recordings of parameters will be collected using a validated patient intake and follow-up questionnaire proforma . Preradiotherapy, followup decayed-missing-filled-tooth Index (DMFT), dental sensitivity, and compliance to three-month FVA will be recorded till one year followup and oral health status of the participant will be recorded using WHO oral health survey proforma 2013.  After oral prophylaxis , slow release aqueous-based topical 5% NaF varnish (Fluoritop- SR, ICPA Health Products Ltd. Mumbai, India) will be applied to one group and  5% NaF varnish enhanced with 2% RECALDENT (CPP-ACP) [MI Varnish, GC India private Ltd. Maharastra, India] will be applied to another group. Statistical Analysis of the data recorded will be done using Statistical Package for the Social Sciences version 27.0 (IBM Corp. Released 2020. IBM SPSS Statistics for Windows, Version 27.0. Armonk, NY: IBM Corp). A p≤0.05 will be considered significant for all statistical inferences.