If a patient has a retained primary molar with no associated problems, what is the most appropriate course of action?

The most appropriate course of action in the scenario of a retained primary molar with no associated problems is to take no treatment. Retained primary molars can often remain in place without causing any issues, especially if they are not contributing to malalignment, are asymptomatic, and do not affect the eruption of the permanent dentition. Monitoring the retained tooth periodically can ensure that there are no changes in its condition or effect on surrounding dentition.

In many cases, primary molars may serve as placeholders for the erupting permanent teeth. If there are no signs of decay or pathology associated with the retained tooth, maintaining it can be beneficial.

Considering the other options: extraction is typically reserved for teeth that pose problems, such as infections or interference with the eruption of permanent teeth. Endodontic therapy would only be indicated if there were signs of pulpitis or infection, which is not the case here. A referral for orthodontic evaluation may be warranted if there were concerns regarding shifting or space issues, but since the tooth is asymptomatic and not presenting problems, it is unnecessary at this time. Hence, opting for no treatment aligns with the best practice for such a situation.