Patients who are oral hygiene noncompliant (OHNC) are more likely to lose teeth after radiation therapy (RT) for head and neck cancer (HNC), which increases the risk of developing osteoradionecrosis. A previous study revealed that patients who were OHNC at baseline (BL) who became oral hygiene compliant during follow-up had the best tooth-failure outcomes. The purpose of this study was to identify factors associated with oral hygiene compliance (OHC), overall, and among those who were BL OHNC.