A four-year-old who hit his front tooth

Correct answer: A. Concussion

• A. CORRECT. CONCUSSION is injury to the supporting structures WITHOUT abnormal loosening and WITHOUT displacement. The tooth is tender to touch or percussion but has normal mobility and remains in its normal position — exactly as described. The minor sulcular bleeding at the time indicates the periodontal ligament was injured, but the absence of both mobility and displacement is what makes this concussion rather than anything more severe.
• B. LATERAL LUXATION is displacement in a non-axial direction, with the tooth usually locked firmly in its new position and often an accompanying alveolar fracture. The occlusion would be altered, and the stem records a normal occlusion.
• C. SUBLUXATION is injury to the supporting structures with INCREASED MOBILITY but still no displacement, and sulcular bleeding is characteristic of it. The stem states explicitly that there was NO increased mobility — and mobility is the single discriminator between subluxation and concussion.
• D. AVULSION is complete displacement of the tooth out of its socket. Note the rule that follows: an avulsed PRIMARY tooth is NEVER replanted, because of the risk of damaging the developing permanent successor.

Note: The grey discoloration appearing weeks later is the EXPECTED sequel of the pulpal haemorrhage — blood breakdown products entering the dentinal tubules. On its own it does NOT establish that the pulp has become necrotic, which is the point of the next question. The full luxation spectrum in order of severity: concussion, subluxation, extrusive luxation, lateral luxation, intrusive luxation, avulsion.

Correct answer: D. Monitoring visits

• A. Pulpotomy is indicated for a VITAL tooth with a carious or traumatic pulp exposure where the radicular pulp remains healthy. There is no exposure here and no evidence the pulp is irreversibly inflamed.
• B. Extraction of an asymptomatic primary incisor with no radiographic pathology is overtreatment, and it creates its own problems with speech development and parental distress.
• C. Pulpectomy is for irreversible pulpitis or necrosis in a restorable primary tooth. Neither is established at this point, and treating on the basis of colour alone would mean treating many teeth that never needed it.
• D. CORRECT. An ASYMPTOMATIC discoloured primary tooth after trauma requires OBSERVATION. Grey discoloration alone is not an indication for intervention: a substantial proportion of these teeth remain vital, and some lighten again over the following months. Review clinically and radiographically at intervals, watching specifically for the findings that DO warrant treatment — a sinus tract or abscess, pain, increasing mobility, a periapical or inter-radicular radiolucency, or pathological root resorption.

Note: Parents need explicit guidance at this appointment, because the appearance is alarming and the answer is to do nothing. Tell them what to watch for and what to return for: a gum boil, swelling, pain, or the tooth becoming loose. A discoloured but asymptomatic tooth is not a failure of care.

Correct answer: B. Pulpectomy with a resorbable filling material and a stainless steel crown

• A. Extraction is reserved for a tooth that is non-restorable, has excessive pathological root resorption, has lost significant bone support, or where the permanent successor is close to eruption. None of those applies to a restorable incisor in a four-year-old.
• B. CORRECT. Persistent pain in a discoloured traumatised primary tooth indicates irreversible pulpitis or necrosis, meaning the RADICULAR pulp is involved. That requires PULPECTOMY — removal of the coronal and radicular pulp, with obturation using a RESORBABLE material such as zinc oxide eugenol, an iodoform-based paste, or a calcium hydroxide/iodoform combination. The filling must resorb in step with the physiological root resorption so that it does not obstruct eruption of the permanent successor — which is why gutta-percha is never used in a primary tooth. Restore with a stainless steel crown for a durable coronal seal.
• C. Pulpotomy removes only the CORONAL pulp and depends on the radicular pulp being healthy. Persistent pain indicates the radicular pulp is involved, which makes pulpotomy the wrong procedure.
• D. Continuing to monitor a tooth that is now symptomatic ignores the very finding that was being watched for. The purpose of the review was to detect this change and act on it.

Note: What this case adds is the SEQUENCE within a trauma presentation — concussion, then discoloration, then observation, then intervention only when symptoms actually appear. Learning the sequence is what prevents both overtreatment at the discoloration stage and undertreatment once the tooth declares itself.