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Management of FPMs of poor prognosis

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Management of first permanent molars of poor prognosis

In some situations, interceptive extraction of FPMs of poor long-term prognosis at 8-10 years of age can allow unerupted SPMs to erupt into an acceptable position. This could facilitate the development of a caries free dentition in the patient, without spacing. However, extraction of permanent molar teeth is demanding for children and may require general anaesthesia which carries risks.

Factors that might contribute to an optimal occlusal outcomes include:

  • patient age; considered optimal between 8-10 years old but this is most relevant for the lower arch, and extraction in the upper arch at an older age may still result in a favourable occlusal outcome
  • class I incisor and molar relationships
  • mild buccal crowding or no buccal segment crowding/spacing
  • second premolars and third molars present on radiograph
  • distal angulation of the SPMs
  • bifurcation of SPMs forming on radiograph

Note that mesial eruption of the upper SPM is more predictable than the lower SPM.

Prior to interceptive extraction of FPMs in children with unerupted SPMs, consider obtaining a specialist paediatric dentist and/or orthodontic opinion, particularly if:

  • any permanent teeth (including third permanent molars) are missing
  • the child has a malocclusion, particularly where there is a class II division 2 or class III malocclusion
  • there are signs of generalised developmental defects

For patients with FPMs of poor prognosis and erupted SPMs consider obtaining a specialist orthodontic opinion if the patient is suitable for orthodontic treatment (e.g. low caries risk) and has a malocclusion that requires orthodontic treatment.

When an emergency extraction of a FPM of poor prognosis is necessary due to pain and infection, and the patient will accept local anaesthesia, consider extracting only the affected tooth before referring for a specialist paediatric or orthodontic opinion (if required).

Routine balancing extractions (i.e. extraction of a contralateral tooth that does not have a poor prognosis) are not recommended in the Royal College of Surgeons of England guideline, as evidence suggests the dental centreline is unlikely to be affected.83  Compensating extractions (i.e. extraction of the same tooth in the opposing arch that does not have a poor prognosis) are not routinely recommended and should be considered on an individual basis if there is a clear occlusal requirement or the upper FPM is likely to be unopposed for a long time.83

In a child with a malocclusion, maintaining a FPM of poor prognosis may be beneficial, allowing extraction of the poor prognosis tooth to be carried out later as part of a comprehensive orthodontic treatment plan.

For first permanent molars with MIH:

  • If there are carious lesions and/or enamel breakdown which are not severe, are not sensitive, do not require restoration and are unlikely to in the future, provide enhanced prevention, including fissure sealants, and monitor.
  • If the molars are sensitive, use glass ionomer cement as a fissure sealant (see Professionally-delivered interventions).
  • If there is good quality enamel with only small defects that require restoration, use adhesive restorative materials. Indirect restorations extending onto sound enamel have better longevity, and it may be necessary to modify the cavity shape to achieve this.

To keep FPMs of poor prognosis free from symptoms until the optimal age for extractions is reached, consider temporising, possibly using a pre-formed metal crown (PMC) approach (i.e. no preparation and no diseased tooth tissue removal) following separator placement.

  • Adhesive restorative materials are not very effective for maintaining FPMs of poor prognosis due to MIH/caries where there is not good quality of enamel or the lesion is extensive. Therefore, PMCs are likely to be more successful.
  • The correct size of crown for FPMs (whether partially or fully erupted) is likely to need to be trimmed to reduce the coronal height. Trimming can be most easily carried out using crown scissors. Stones (blue and brown) are then used to polish away sharp edges of the crown.
  • As it can be difficult to remember the exact pre-restoration status of the tooth/teeth after they are restored, photographic records can be useful for future treatment planning.

Photograph showing a pre-formed metal crown placed on a first permanent molar of poor prognosis

Image showing a FPM with a stainless steel crown in place prior to the optimal age for extraction.

If in doubt at any stage, temporise the teeth, continue prevention and refer the child for specialist paediatric dental or orthodontic opinion (see Referral).