Final answer:
The appropriate treatment for a broken barbed broach in a tooth canal with radiolucency at the apex includes options like extraction, apicoectomy with retrofilling, preparing and obturating to the blockage point, or formocresol application.
Step-by-step explanation:
The student's question pertains to the appropriate course of treatment for a maxillary incisor where a fragment of a barbed broach is broken off and wedged in the middle third of a canal. There's also a radiolucency observed at the apex. Given that the fragment cannot be bypassed or removed, the treatment of choice would include either extracting the tooth, performing an apicoectomy with retrofilling, preparing and obturating to the point of blockage, or using formocresol to fix necrotic tissue. A suitable professional assessment must be made considering the patient’s current condition, potential for healing, and overall dental health.