28.2 Luxation Injuries, Avulsion and Replantation

3. Luxation Injuries in Permanent Teeth

Luxation injuries represent damage to the tooth supporting structures (periodontal ligament and alveolar bone socket), often accompanied by neurovascular disruption.

Luxation Spectrum and Primary Clinical Signs
  ┌───────────────────────┬───────────────────────┬───────────────────────┐
  │ Concussion            │ Subluxation           │ Extrusive Luxation    │
  │ - Tender to touch     │ - Tender to touch     │ - Partial extrusion   │
  │ - No displacement     │ - Increased mobility  │ - Elongated crown     │
  │ - No mobility         │ - Sulcular bleeding   │ - High mobility       │
  │ - No splint required  │ - Flexible splint 2 wk│ - Flexible splint 2 wk│
  ├───────────────────────┴───────────────────────┴───────────────────────┤
  │ Lateral Luxation                              │ Intrusive Luxation    │
  │ - Displaced laterally (palatally / bucally)   │ - Displaced apically  │
  │ - Apex locked in cortical bone                │ - Crushed PDL / bone  │
  │ - Metallic percussion sound; zero mobility    │ - Metallic sound      │
  │ - Disengage & reposition; flexible splint 4 wk│ - Spontaneous / ortho │
  └───────────────────────────────────────────────┴───────────────────────┘

Comprehensive Management of Luxations

[!IMPORTANT] Critical Endodontic Protocol in Mature Intrusive Luxations: In permanent teeth with closed apices, intrusive luxation causes total rupture of the apical neurovascular bundle and crushes the periodontal ligament. Pulpal necrosis is virtually 100% guaranteed, and necrotic tissue will rapidly trigger aggressive external inflammatory root resorption that can destroy the root within months. Clinicians must electively initiate root canal treatment within 2 weeks of the injury, placing non-setting calcium hydroxide intracanal medicament to prevent osteoclastic root resorption.

4. Avulsion of Permanent Teeth: Chairside Emergency Protocols

Avulsion is the complete displacement of a tooth out of its alveolar socket. The long-term prognosis depends primarily on the viability of the periodontal ligament (PDL) cells remaining on the root surface.

                    Avulsion Emergency Decision Pathway
                                     │
        ┌────────────────────────────┴────────────────────────────┐
        ▼                                                         ▼
Extra-Oral Dry Time < 60 Minutes                          Extra-Oral Dry Time > 60 Minutes
  (Viable / Reparable PDL Cells)                            (Non-Viable / Necrotic PDL Cells)
  - Rinse root gently with saline/milk                      - Inevitable ankylosis / replacement resorption
  - Irrigate socket to remove clot                          - Remove necrotic PDL tissue
  - Replant with gentle digital pressure                    - Soak in 2% Sodium Fluoride for 20 min
  - Flexible splint for 2 WEEKS                             - Replant and flexible splint for 4 WEEKS
  - Mature tooth: initiate RCT at 7–14 days                 - Endodontic therapy (RCT) intra- or extra-oral
  - Immature tooth: monitor revascularisation               - Inform family of eventual tooth loss

Handling and Storage Media

• Handling: Always hold the avulsed tooth by the enamel crown only. Never touch, scrape, brush, or debride the root surface, as mechanical trauma destroys the fragile monolayer of viable cementoblasts and PDL fibroblasts.
• Storage Media Quality Hierarchy:
  1. Hank's Balanced Salt Solution (HBSS): The gold standard; optimal osmolarity, physiological pH, and essential nutrients.
  2. Cold Pasteurised Bovine Milk: Readily accessible; physiological osmolarity, essential nutrients, and low bacterial count.
  3. Saline Solution (0.9% NaCl): Isotonic; maintains cell volume temporarily.
  4. Saliva (Child's Buccal Sulcus or Spat into a Cup): Acceptable if no other medium is available, but carries risks of bacterial contamination or swallowing/aspiration.
  5. Tap Water (STRICTLY CONTRAINDICATED): Severely hypotonic; induces immediate cellular swelling, osmotic lysis, and rapid necrosis of PDL cells.

Immediate Management Protocols Based on Dry Time

Extra-Oral Dry Time < 60 Minutes (Viable PDL Cells)

1. Root Preparation: If contaminated with debris, rinse the root gently with a stream of sterile saline or cold milk. Do not scrub or sterilise the root.
2. Socket Preparation: Irrigate the socket gently with sterile saline to clear the blood clot. Do not curette or scrape the bony socket walls.
3. Replantation: Replant the tooth into the socket using light, steady finger pressure. Verify position clinically and radiographically.
4. Splinting: Apply a flexible, passive splint for 2 weeks.
5. Systemic Antibiotics: Prescribe a 7-day systemic antibiotic course to prevent bacterial contamination from compromising PDL healing:
   • Patients > 12 years: Doxycycline (100 mg twice daily on day 1, then 100 mg once daily for 6 days).
   • Patients < 12 years: Amoxicillin (or Phenoxymethylpenicillin) at age-appropriate dosages (tetracyclines/doxycycline are contraindicated due to the risk of intrinsic enamel discolouration and enamel hypoplasia in developing permanent teeth).
6. Tetanus Prophylaxis: Verify immunization status. If the injury occurred in a contaminated environment and the last booster was > 5 years ago, refer immediately to the GP or Emergency Department.
7. Endodontic Management:
   • Mature Closed Apex: Pulpal revascularisation is impossible. Initiate root canal treatment between 7 and 14 days post-replantation (prior to splint removal). Extirpate the pulp, place a non-setting calcium hydroxide dressing for 2 to 4 weeks, and then obturate with gutta-percha. Failure to initiate RCT within 14 days invites aggressive external inflammatory root resorption.
   • Immature Open Apex: Revascularisation is biologically possible. Do not perform immediate root canal therapy. Monitor clinically and radiographically every 4 weeks. If signs of pulpal necrosis or inflammatory resorption appear, initiate apexification (MTA apical barrier) or regenerative endodontic procedures immediately.

Extra-Oral Dry Time > 60 Minutes (Non-Viable PDL Cells)

When extra-oral dry time exceeds 60 minutes, all periodontal ligament cells have undergone irreversible necrosis. Replantation will inevitably result in ankylosis (replacement root resorption), wherein osteoclasts and osteoblasts resorb the root dentine and replace it with bone, eventually causing crown infra-occlusion and tooth loss:

1. Mechanically remove the necrotic PDL tissue from the root surface using gauze or a curette.
2. Soak the tooth in a 2% Sodium Fluoride (NaF) solution for 20 minutes prior to replantation. Fluoride ions bind to root surface hydroxyapatite to form fluorapatite, which temporarily retards osteoclastic resorption.
3. Irrigate the socket, replant, and place a flexible splint for 4 weeks.
4. Endodontic treatment may be carried out extra-orally prior to replantation or initiated at 7 to 14 days post-replantation.

Follow-up after any luxation or replantation is prolonged and must be arranged at the time of the injury. Clinical and radiographic review is required at intervals over at least a year, and often longer, to detect pulp necrosis, external inflammatory resorption, replacement resorption and ankylosis, and loss of marginal bone. Parents and patients must be told what to watch for between reviews — discoloration, tenderness, a sinus or increasing mobility — and told that a tooth which appears normal at one review can still fail later. In a growing patient, ankylosis of an upper incisor causes infraocclusion as the alveolus develops around it, so long-term planning involves the orthodontist and the restorative team together.