When should the primary central incisors be considered for extraction if they are erupted lingually to the mandibular permanent central incisors?

The correct response emphasizes the importance of the primary central incisors' root development and their stability in the dental arch. By the ages of 7 ½ to 8 ½, the primary central incisors should be evaluated for extraction if they are firm and exhibit complete root formation. This timing aligns with the eruption of the permanent central incisors, as these teeth typically emerge around ages 6 to 8. If the primary teeth have fully developed roots and are stable, they may be retaining in the arch longer, contributing to proper spacing and alignment for the incoming permanent teeth.

When primary teeth are still firm at this stage, it is crucial to consider whether they are obstructing the eruption path of the permanent successors. If they began to erupt lingually and are preventing proper alignment of the permanent incisors, extraction might be warranted only under specific circumstances, primarily related to their stability and time frame regarding eruption.

This perspective also accounts for the overall timing of dental transitions, as intervention timing is critical to avoid longer complications such as crowding or misalignment of permanent teeth, which may arise if the primary teeth remain too long. Thus, determining the firmness and root presence of the primary incisors by age 7 ½ to 8 ½ is