When mandibular permanent central incisors are erupting lingually to primary incisors, what should be the course of action?

When mandibular permanent central incisors are erupting lingually to primary incisors, the recommended course of action is to consider extraction if the primary incisors are firm and have fully developed roots, by the age of 7½ to 8½ years. This approach is based on the developmental timeline of the teeth and the implications for proper occlusion and alignment.

The reason this option is appropriate is that it allows for evaluation of the primary teeth's mobility and root development. If the primary incisors are still firm, removing them prematurely could lead to issues with space management and potential dental crowding. Monitoring the primary teeth until the child reaches the specified age ensures that any decision made regarding extraction is based not only on the eruption of the permanent incisors but also on the readiness of the primary teeth to be lost naturally.

In contrast, the other choices suggest more aggressive approaches, such as extracting the primary incisors indiscriminately or including adjacent teeth, which may not be necessary and could disrupt the established dental arch without proper justification. The emphasis on assessment of root maturity and timing ensures a more conservative and thoughtful strategy that prioritizes the child's dental health and development.