28.3 Primary Tooth Trauma and Splinting Specifications

5. Trauma to the Primary Dentition & Splinting Specifications

                     Trauma to the Primary Dentition
                                   │
     ┌─────────────────────────────┴─────────────────────────────┐
     ▼                                                           ▼
Primary Tooth Luxations / Fractures                     Avulsion of Primary Tooth
  - Risk of displacing primary root into                   - MANDATORY RULE:
    underlying permanent tooth germ.                         NEVER REIMPLANT AN AVULSED
  - If root apex is displaced toward                         PRIMARY TOOTH!
    permanent germ ──> EXTRACT IMMEDIATELY                 - Avoids iatrogenic destruction
  - If apex is displaced AWAY from germ                      of permanent tooth germ
    ──> Allow spontaneous repositioning                     - Reassure parents

The Cardinal Rule in Primary Tooth Avulsion

[!CAUTION] NEVER Reimplant an Avulsed Primary Tooth: Replantation of an avulsed primary tooth is strictly contraindicated under all circumstances. Replanting the tooth carries an unacceptably high risk of introducing bacterial infection and causing direct mechanical trauma to the delicate permanent tooth germ lying immediately adjacent to the primary socket. Sequelae in the permanent successor include:

• Turner's Hypoplasia (Turner's Tooth): Localized circular enamel hypoplasia and brown/yellow discolouration.
• Crown or Root Dilaceration: Severe angulation/bending of the permanent crown or root.
• Partial or Complete Arrest of Tooth Germ Development: Resulting in odontoma-like malformations or failure of eruption.

Splinting Specifications in Dental Traumatology

• Splint Characteristics: Splints must be flexible (physiological) and passive, allowing slight physiological mobility during functional movements (mastication, speech). Rigid splinting immobilises the root, promoting osteoclastic activation and ankylosis.
• Splint Materials: Light orthodontic archwire (up to 0.016" round stainless steel wire) or nylon monofilament fishing line (0.3–0.4 mm diameter), bonded to the middle third of the labial enamel surfaces using flowable composite resin.

6. Clinical Traps, Pitfalls & Worked Scenario

[!WARNING] Clinical Trap: Performing Root Canal Therapy on Root-Fractured Teeth Prematurely: A 15-year-old patient suffers a horizontal root fracture of tooth 11 in the middle third. At the 2-week review, the tooth gives a negative response to cold and electric pulp testing. A clinician might conclude the pulp is necrotic and initiate root canal therapy across the fracture line. This is an error. Acute trauma induces prolonged pulpal neuropraxia that can yield false-negative sensibility readings for up to 3 to 6 months. Endodontic intervention is indicated only if the coronal segment displays verifiable signs of infection and necrosis (e.g., persistent tenderness, sinus tract, expanding radiolucency at the fracture line). Even then, endodontic instrumentation must be restricted to the coronal segment only.

[!NOTE] Clinical Trap: Prescribing Doxycycline to Children Under 12 Years: An 8-year-old child presents with an avulsed upper permanent central incisor replanted within 30 minutes. The clinician writes a prescription for doxycycline as recommended in adult avulsion protocols. Doxycycline binds calcium ions and deposits in actively mineralising tooth buds, causing permanent intrinsic tetracycline discolouration and enamel hypoplasia in the unerupted permanent teeth. In children under 12 years of age, amoxicillin or phenoxymethylpenicillin must be prescribed instead.

Worked SBA Clinical Scenario

Scenario: A 13-year-old boy presents to the dental clinic 45 minutes after being struck in the mouth by a cricket ball. His maxillary right central incisor (tooth 12) is displaced palatally, firmly locked into the alveolar bone, and emits a dull, high-pitched metallic note upon light tapping. The tooth has zero mobility. Periapical radiographs show a widened periodontal ligament space coronally, with the root apex tilted labially into the cortical plate. Soft tissues display minor sulcular laceration without embedded foreign bodies. Medical history is unremarkable, and neurological triage reveals no loss of consciousness, nausea, or dizziness.

Question: What is the correct definitive diagnosis, immediate repositioning technique, and splinting duration according to IADT guidelines?

Clinical Reasoning Formulation:

1. Diagnostic Identification: A tooth displaced in a non-axial direction (crown palatally), locked firmly into the alveolar cortical bone plate with zero mobility and a high metallic sound, meets the diagnostic criteria for a Lateral Luxation.
2. Immediate Operative Management: Under local anaesthesia, the root apex must be disengaged from the labial cortical bone plate by applying combined apical and labial digital pressure, carefully guiding the tooth back into its anatomical socket.
3. Splinting Selection and Duration: In accordance with IADT 2020 guidelines, lateral luxations involve alveolar bone comminution and require a flexible, passive splint for 4 weeks (longer than the 2 weeks required for simple extrusive luxation).
4. Follow-Up: Monitor pulpal sensibility and monitor for signs of pulp necrosis or inflammatory resorption.

Sequelae and Parental Advice

The reason primary tooth trauma is managed conservatively is the proximity of the developing permanent successor: the apex of an intruded primary incisor lies immediately labial to the permanent tooth germ. Possible sequelae to the successor include enamel hypoplasia or opacity, crown or root dilaceration, arrest of root formation, and eruption disturbance, and parents must be warned of this possibility at the time of the injury and the warning recorded. Follow-up is clinical and radiographic, and the child should be reviewed for discoloration, sinus formation, mobility and the eventual eruption of the successor.