Which scenario indicates a need for periapical surgery?

The scenario that best indicates a need for periapical surgery is the case where an existing root canal filling may cause root fracture.

In this context, periapical surgery is often considered when there is a risk associated with the current treatment that may compromise the integrity of the tooth. If the root canal filling is overextended, poorly placed, or has resulted in changes to the tooth structure or surrounding bone, it could potentially lead to root fracture, which might ultimately necessitate extraction of the tooth. Periapical surgery can help address these issues directly by either removing the problematic filling material or performing an apicoectomy, which involves removing the tip of the root where inflammation might be causing problems.

Other scenarios, such as faulty root canal treatment, could suggest a need for retreatment rather than surgical intervention. While involving other anatomical structures and extensive bony defects are important considerations in treatment planning, they do not directly imply an immediate need for periapical surgery in the same way that the risk of root fracture does.