Prevention is a good start. Dietary avoidance of sucrose is good to prevent caries (or at least rinsing after ingesting sucrose…gotta keep lactic acid bacteria from going nuts) and brushing and flossing is good to prevent periodontal inflammation and bone loss. Sometimes, people with "good" teeth don't realize they may have "bad" gums (and lose teeth as a result of periodontal problems).
But… you never know. You may get into an accident, bite on something hard, get into a knock-out game etc. If you have children, they may require orthodontics or exodontics. Dentists can also assist medicine in the diagnosis of other problems that sometime manifest first, in the mouth. Eg., dentists often are the first to detect various immunopathologies, oncological problems, and other systemic disease.
So, even if you think you have "good" teeth, it may still save you money and be beneficial to your health for preventive maintenance alone to have a dental health plan and be able to schedule regular visits as specified by someone who can set-up the best schedule for you, as an individual. As far as which ental health plan, maybe you need to consult an insurance specialist.