Dental trauma and avulsed teeth — formative SAQs

SAQ 1 — The boy who knocked out a permanent incisor on the playground (10 marks, 15 minutes)

An eight-year-old boy has fallen on the playground and knocked out his upper left permanent central incisor. The tooth was found on the ground about five minutes ago. A teacher brings him to you holding the tooth wrapped in a tissue. ^[1]

a) Describe the immediate first-aid you would advise had been done at the scene, including how to handle the tooth and what to do if it cannot be replanted. (3 marks) ^{[1] [9]}

b) Name the preferred storage media for transport, and explain why plain water is contraindicated. (2 marks) ^[9]

c) State the single most important prognostic factor, and the dry time associated with the best outcome. (2 marks) ^[7]

d) Outline the definitive dental management once the tooth is replanted, including splinting and root canal treatment for this closed-apex tooth. (3 marks) ^{[1] [8]}

Model answer

The scene first-aid is to find the tooth, pick it up by the crown only (never the root), rinse a dirty root gently under running water for about ten seconds, and replant a permanent tooth immediately into its socket the right way up, then have the child bite gently on a clean handkerchief or gauze to hold it. If it cannot be replanted, it is stored in cold milk, Hank's balanced salt solution, saline, or the cheek, and the child is taken to a dentist immediately. The tooth must never be scrubbed, scraped, dried, or stored in plain water. ^{[1] [9]}

The preferred storage media are cold milk or Hank's balanced salt solution (or saline or saliva), because they are physiologically balanced and keep the periodontal-ligament cells on the root viable. Plain water is contraindicated because it is hypotonic and ruptures those cells by osmosis, destroying the only cells capable of re-forming a healthy attachment. ^[9]

The single most important prognostic factor is the extra-alveolar dry time, the time the tooth spends out of the socket and dry. Periodontal-ligament cells begin to die within minutes on a dry surface and are largely non-viable after about sixty minutes; a tooth replanted within twenty minutes has the best prognosis. ^[7]

Once the tooth is replanted, the dentist cleans the socket if needed, confirms the position, and applies a short flexible (physiological) splint for about two weeks, because flexible splinting permits the small movement that protects the healing ligament from ankylosis. Because this tooth has a closed apex its pulp will necrose, so root canal treatment is started at seven to ten days after replantation; a systemic antibiotic course and tetanus prophylaxis for a contaminated wound complete the early care. ^{[1] [8]}