Primary site of tumor
– Posterior mandible is more commonly affected by ORN because of its
compact and dense nature
Proximity of tumor to bone
Extent of mandible included in primary radiation field
State of dentition – odontogenic and periodontal disease
Poor oral hygiene
Radiation dose >60 Gy
Use of brachytherapy
Nutritional status
Concomitant chemo-radiation
Ill-fitting tissue borne prosthesis resulting in chronic trauma
Acute trauma from surgical procedures to the jaw
Advanced stage tumors