Infraoccluded Teeth is where teeth submerge below the occlusal plane of neighbouring teeth. 

• Mild – 1-2 mm below the occlusal plane of adjacent teeth 
• Moderate – occlusal surface level with the contact point of adjacent teeth 
• Severe – occlusal surfaces below inter-proximal contact 

NOTE: Rapid infra-occlusion especially at an early age has a greater potential for disruption of alveolar development.  

The aetiology of infra-occlusion is unknown but potential causes are: 

• Ankylosis – fusion of the cementum to the alveolar bone (most common cause) 
• Periodontal membrane disorders 
• Local mechanical trauma 
• Local infection 
• Disturbed local metabolism 
• Chemical/thermal irritation 
• Systemic diseases:
  • Congenital syphilis 
  • Endocrine disorders 
• Abnormal pressure from the tongue 
• Disturbance in normal hard tissue resorption and deposition  

Diagnosis of infraocclusion: 

• Clinical examination: 
  • A disturbance in the occlusal plane is evident 
  • Sharp solid high pitched tone on percussion (when 20% ankylosed) 
  • Immobility (when 10% ankylosed) 
• Radiographs: 
  • Helps rule out other potential causes: Primary failure of eruption, pathology or impaction.
  • To verify the presence or absence of permanent successor  
  • DPT is the preferred view – due to bilateral presentation of infra occlusion and to assess other dental anomalies and determine orthodontic treatment need. 

Consequences of infraocclusion: 

• Tipping of adjacent teeth  
• Over eruption of opposing teeth  
• Lateral open bite or cross bite 
• Caries in adjacent teeth  
• Hypoplasia or deflection of successor tooth 
• Impaction of permanent successor 
• Delayed exfoliation of primary tooth 
• Progression of infra-occlusion 
• Early extraction of severely infra-occluded primary molar 
• Difficult extraction 

Monitoring infraocclusion in general dental practice: 

1. Record the site and number of infra-occluded teeth  
2. Measure and record the severity of infra-occlusion 
3. Take radiographs to determine presence/absence of successor  
4. Determine treatment plan for infra-occluded tooth and inform parental guardian. 
5. Review patient every 3-6 months to assess the progression of infra-occlusion, re-evaluate treatment options at each recall appointment.  

Treatment options of Infraoccluded Teeth in the absence of a permanent successor: 

1. Retain (mild-moderate infra-occlusion without permanent successor in uncrowded arches can be retained and restored to function) 
2. Extraction 

Always take into consideration: 

• Rate of progression of infra-occlusion 
• Age of diagnosis  
• Rate of root resorption  
• Orthodontic needs of patient 

Treatment options of infra-occluded teeth in the presence of a permanent successor: 

• 96.7% exfoliate with normal eruption of permanent successor with up to 6 months delay. 
• Mild- moderate infra-occlusion should be monitored clinically and radiographically every 3-6 months. 
• Occlusion can be re-established with composite/stainless steel crowns. 
• Consider extraction and space maintainer if: 
  • Permanent successor has an altered path of eruption 
  • Failure of root resorption 
  • Delayed exfoliation of primary teeth beyond 6 months  
  • Significant tipping of adjacent teeth or opposing tooth over-eruption 
  • If child planned for general anaesthetic  
• Avoid extraction in patients who are immunocompromised or have bleeding disorders.

See also Balancing & Compensating Extractions