What is the most appropriate action if a maxillary third molar has been inadvertently displaced and is no longer visible?

In the situation where a maxillary third molar has been inadvertently displaced and is no longer visible, the most appropriate action is to close the access and refer the patient for oral surgery. This approach ensures that the situation is managed safely and effectively by a specialist who is trained to handle complications associated with tooth extraction, including those involving displaced teeth.

When a tooth is not visible, it could potentially be lodged in areas that are difficult to access surgically. An oral surgeon is equipped with the skills and tools necessary to locate and remove the displaced tooth while minimizing risks to the surrounding anatomical structures, such as nerves and blood vessels. This referral also allows for a thorough evaluation and management plan to be made, possibly including imaging studies to locate the tooth.

The other options may involve unnecessary or undue risk. For example, using a Caldwell-Luc approach could expose the patient to added surgical trauma without guaranteeing success in locating the tooth. Similarly, extending an incision to access the infratemporal fossa may lead to complications without effectively removing the tooth. Contacting the patient to discuss next steps could delay appropriate treatment and might result in further complications. Hence, opting to close the access and obtain a referral for specialized surgical intervention is the logical and safest choice in this scenario.