Primary care physicians and nurses have numerous opportunities to assist in the prevention of dental caries, periodontal diseases, malocclusion, trauma to the mouth and teeth, and oral cancer. This is the first of two articles that provide background for the US Preventive Services Task Force recommendations for interventions by physicians, nurses, and other clinicians to prevent these oral diseases and conditions. Physicians and other health professionals are urged to be aware of these opportunities and to take appropriate action in collaboration with the patient's dentist.