An avulsed tooth has been replanted. What finding is most likely at follow-up?

Correct answer: A. Ankylosis with replacement resorption

• A. CORRECT. Most replanted avulsed teeth — particularly those with an extended dry extra-oral time — lose periodontal ligament cell viability. Without a vital PDL, bone heals directly onto the root surface, producing ANKYLOSIS (replacement resorption). The clinical signs are a high metallic percussion note, absence of physiological mobility, and progressive infra-occlusion as the surrounding alveolus continues to grow while the ankylosed tooth does not. Radiographically the PDL space disappears and root substance is gradually replaced by bone.
• B. Root development can continue only in an immature tooth whose apical papilla survived — a possible but much less common outcome, and one favoured by very short extra-oral times.
• C. Increased probing depths are not the characteristic finding; the periodontal attachment is typically maintained around an ankylosed tooth.
• D. Ankylosis produces the OPPOSITE of mobility. A replanted tooth that becomes MORE mobile suggests inflammatory resorption or failure, not the expected healing pattern.

Note: Prognosis is dominated by extra-oral dry time. Under 60 minutes in a suitable medium (HBSS, milk, saline) gives the best chance of PDL healing; beyond 60 minutes dry, ankylosis is the expected outcome. In a growing patient, infra-occlusion from ankylosis has serious long-term consequences and requires planning.