First permanent molar extractions are often required in children, as they can develop first permanent molars of poor prognosis, requiring enforced extraction. This is due to 6’s being susceptible to caries and their association with MIH.  

Before deciding whether a tooth needs extracting, good quality radiographs are required. A GDP decides whether a tooth is un-restorable whereas an orthodontic opinion is required when deciding to electively extract sound teeth.  

  • If GA is required for extraction- an orthodontic opinion is required beforehand to prevent multiple GA’s 

An ideal timing of extraction is required for the 7 to replace the position of the 6 and the 8 to replace the position of the 7.

Achieving good space closure is much easier in the upper arch in comparison to the lower arch due to the difference in bone density.

Therefore, timing of extraction of the lower 6 is important. You should aim to hold off extracting the lower first permanent molar until there is radiographic evidence of bifurcation of the second permanent molar. This usually occurs between the ages of 8-10 years.  

IF THE LOWER 6 IS EXTRACTED EARLIER THAN IDEAL…IF THE LOWER 6 IS EXTRACTED LATER THAN IDEAL…
The 5 can drift distally into the extraction space creating spacing and poor occlusal contacts.The 7 may tip mesially or drift into the extraction space creating spacing and poor occlusal contacts.
The labial segment may retrocline, causing an increased overbite.The 5 can drift distally into the extraction space creating spacing and poor occlusal contacts.

Factors influencing whether the extraction of a first permanent molar (FPM) is recommended for balancing or compensating extraction: 

  • Which first permanent molar requires enforced extraction 
  • The long term prognosis/ condition of first permanent molar 
  • The number of teeth present and developmental status of the dentition  
  • Underlying malocclusion 

As a general rule the compensating extraction is recommended when the extraction of the lower FPM is required. 

  • This is to avoid over eruption of the which can prevent desirable mesial movement of the lower teeth. The evidence supporting this is weak however..  

The routine compensating extraction of a sound lower first permanent molar, in conjunction with enforced extraction of the upper first permanent molar is not recommended.  

Routine balancing extraction of first permanent molars to preserve centreline shift  is not routinely recommended. 

Ectopic Eruption Of First Permanent Molars

Ectopic eruption of a first permanent molar occurs when the tooth follows an abnormal eruption pathway. The mesial surface of the first permanent molar contacts the distal surface of the second primary molar and causes varying degrees of resorption.

Ectopic eruption of the first permanent molar is usually diagnosed between the ages of 5-7 years following radiographic examination. 

Reversible ectopic eruption – the permanent molar spontaneously self corrects and erupts into a normal position.  

Irreversible ectopic eruption –The permanent molar remains blocked against the second primary second molar. 

Degrees of resorption: 

  • Grade 1 (mild):  Limited resorption to cementum or with minimum dentine penetration 
  • Grade 2 (moderate): resorption of dentine without pulp exposure 
  • Grade 3 (severe): resorption of the distal root causing pulp exposure 
  • Grade 4 (very severe): resorption affecting the mesial root of the primary second molar. 

Causes of ectopic first permanent molar eruption: 

  • Abnormally large size of primary and secondary dentition 
  • Abnormal crown morphology of primary second molars 
  • Small maxilla/mandible  
  • Posterior position of the maxilla in relation to the cranial base 
  • Abnormal eruption angle of the first permanent molar 

Management: 

  1. Monitor  
    • Includes clinical and radiographic examination 3-6 months following diagnosis. 
    • Spontaneous correction can occur in all cases but most commonly occurs in cases with grade 1 resorption of the E.  
  2. Separate 
    • Suitable in cases of mild abnormal angulation of the first permanent molar. 
    • The crown of the 6 must be accessible clinically. 
    • The following may be used to dis-impact the 6: 
      • Brass ligature  
      • Spring type wedge  
      • Orthodontic elastic separator 
      • Kesling separator  
  3. Active appliance 
    • Suitable in cases whether the crown of the 6 is inaccessible and the degree of impaction is severe.  
    • Active appliances usually consist of a band on the
  4. Extraction of the E followed by appliance therapy 
    • Suitable in cases whether the E is of poor prognosis with severe resorption/caries/abscess 
    • Following the extraction of the E the 6 is likely to tip mesially therefore appliance therapy is required. 
    • Removable appliance or fixed appliance can be used to distalise the 6.
References

Cobourne, M.T., Williams, A. and Harrison, M., 2014. National clinical guidelines for the extraction of first permanent molars in children. British dental journal, 217(11), pp.643-648.

MFDS, R., 2013. The psychosocial and affective burden of posttraumatic neuropathy following injuries to the trigeminal nerve.

Ashley, P. and Noar, J., 2019. Interceptive extractions for first permanent molars: a clinical protocol. British dental journal, 227(3), pp.192-195.

Cobourne, M., Williams, A. and McMullan, R., 2009. A guideline for first permanent molar extraction in children. RCS Publications http://www. rcseng. ac. uk/fds/publications-clinicalguidelines/clinical_guidelines/index. html [Accessed 3rd January 2013].

See also Infra-occluded teeth