Tooth Intrusion

Tooth intrusion is an axial displacement of the tooth deeper into the alveolar bone, with crushing of the periodontal ligament and the pulpal vessels. It is a severe luxation injury, making up about 0.5 to 2% of permanent tooth injuries and a higher share of primary tooth injuries.

It occurs mostly in children aged 2 to 4 years (primary teeth) and 6 to 12 years, and the maxillary incisors are most commonly involved. The tooth may seem to have been lost, and a radiograph is needed to find it.

Pathophysiology. Axial force drives the tooth into the socket and compresses the apical neurovascular bundle and the periodontal ligament, often fracturing the socket wall. Pulp necrosis is very likely in mature teeth with severe intrusion.

Repair can bring replacement resorption (ankylosis), inflammatory resorption or marginal bone loss. In primary teeth the root apex can be displaced towards the permanent tooth germ, damaging it.

A tooth that seems shorter or missing, with the crown partly or completely buried, a high metallic percussion note, a firm tooth with no mobility, bleeding from the sulcus, and gingival laceration. Primary tooth intrusion may displace the root labially or palatally.

Record the degree of intrusion in millimetres and the stage of root development. Check for other dental, alveolar and facial injuries and tetanus status.

Head injury, airway concern, other fractures, suspected aspiration of a missing tooth, and heavy contamination need urgent assessment.

• Clinical examination of crown height compared with the neighbouring teeth, mobility and percussion.
• Periapical and occlusal radiographs, with a lateral view of the primary tooth, to show the position of the root in relation to the permanent germ. Cone beam CT in selected cases.
• Distinguish from avulsion by finding the tooth on imaging.
• Pulp sensibility tests are unreliable at first and are repeated at follow up.
• Tetanus status.

Differential diagnosis.

• Tooth avulsion
• Exfoliation or congenital absence of the tooth
• Lateral luxation
• Root or crown root fracture
• Alveolar fracture
• Delayed eruption
• Ankylosis from earlier injury

• Primary teeth: if the apex is displaced towards the permanent germ (labial displacement is shown on a lateral radiograph with the apex towards the germ), extract the tooth. If the root is displaced away from the germ, leave the tooth for spontaneous re-eruption, which usually occurs within 2 to 6 months. Monitor for infection and extract if abscess forms.
• Permanent teeth, immature (open apex): intrusion under 7 mm: allow spontaneous re-eruption and monitor, with orthodontic repositioning if it has not erupted within 2 to 4 weeks. Over 7 mm: orthodontic or surgical repositioning.
• Permanent teeth, mature (closed apex): intrusion under 3 mm: allow spontaneous re-eruption and monitor for 2 to 4 weeks, then use orthodontic repositioning if there is no movement. Intrusion of 3 to 7 mm: orthodontic or surgical repositioning. Over 7 mm: surgical repositioning.
• Root canal treatment after 2 to 3 weeks in mature teeth because pulp necrosis is expected, with calcium hydroxide dressing for 1 to 4 weeks before the permanent filling.
• Flexible splint for 4 weeks after surgical repositioning, with soft tissue suturing.
• Antibiotics: doxycycline 100 mg orally twice daily for 7 days in patients aged 12 years and over, avoided in pregnancy, breastfeeding and renal impairment, or amoxicillin 500 mg orally three times daily for 7 days (reduce to 500 mg every 12 hours at eGFR 10 to 30). Children under 12: amoxicillin 125 mg three times daily at 1 to 11 months, 250 mg at 1 to 4 years and 500 mg at 5 to 11 years, for 7 days.
• Tetanus toxoid 0.5 mL intramuscularly if vaccination is incomplete or the last dose was over 10 years ago, with tetanus immunoglobulin 250 IU intramuscularly (500 IU after 24 hours or heavy contamination) when status is unknown or incomplete.
• Chlorhexidine 0.12% mouthwash 10 mL twice daily for 1 week, soft diet for 2 weeks.
• Analgesia: paracetamol 1 g every 6 hours (maximum 4 g daily) with ibuprofen 400 mg every 8 hours with food. Children use paracetamol 15 mg/kg every 4 to 6 hours (maximum 75 mg/kg daily) and ibuprofen 5 to 10 mg/kg every 6 to 8 hours.

Monitoring. Review at 2 weeks, 4 weeks, 6 to 8 weeks, 6 months, 1 year, and yearly for 5 years, with radiographs and percussion. Watch for ankylosis, inflammatory resorption, pulp necrosis and marginal bone loss. In primary teeth, review the eruption of the permanent tooth for enamel defects.

Referral and escalation. Refer to a dental trauma service or paediatric dentistry. Urgent referral for severe intrusion, other injuries or infection.