Final answer:
The Federal government has a primary role in oral health research.
Step-by-step explanation:
The government entity that has a primary role in oral health research is the Federal government. While state and local governments also play a role in public health, oral health research is primarily conducted at the federal level through various agencies and organizations. For example, the National Institute of Dental and Craniofacial Research (NIDCR) is a branch of the National Institutes of Health (NIH) that focuses on oral health research.