An instrument separates 3 mm from the apex and the canal is obturated to the level of the fragment. Which scenario carries the BEST prognosis?

Correct answer: D. A vital pulp with no periapical lesion

• A. The presence of a periapical lesion signals existing infection, worsening the outlook even if the pulp was vital coronally.
• B. A necrotic pulp means the canal was infected before the fragment blocked access to its apical portion.
• C. This is the worst combination — an infected necrotic canal with established periapical disease, and a fragment preventing disinfection of the apical third.
• D. CORRECT. The prognosis after instrument separation is determined not by the fragment itself but by WHAT WAS LEFT BEHIND IT. In a VITAL case the canal contents were essentially sterile before instrumentation, so sealing a fragment into an uninfected canal is well tolerated — success rates approach those of uncomplicated treatment. The absence of a periapical lesion confirms there was no established infection.

Note: A separated instrument is not itself a failure. What matters is whether infected tissue remains apical to it. Inform the patient, document it, and monitor — retrieval attempts often cause more harm than the fragment.