From Volume 49, Issue 7, July 2022 | Pages 562-566
First permanent molars (FPM) are often of poor prognosis due to caries or molar incisor hypomineralization. If extraction can be planned then FPM may be extracted at a suitable time to allow spontaneous space closure from the second molar, or retained for the space to be used for orthodontics in the future. There are several evidence based patient and dental factors to consider in planning these cases. This paper illustrates these factors through a case series.
First permanent molars (FPM) of poor prognosis present a restorative and orthodontic challenge. If the child is not in pain and the removal of the tooth can be planned, then there is the opportunity to extract the FPM at a time to maximize spontaneous space closure by the second permanent molar (SPM) or for it to be retained to provide space for orthodontic treatment in the future.
The following factors, however, must be considered:
The aim of this article is to illustrate the factors through clinical cases, demonstrating ideal and complex cases as well as less favourable outcomes.
This patient presented aged 9.5 years with a Class I incisor relationship, slightly spaced upper and lower arches and MIH affecting all four FPMs (Figure 1). As there was enough space to accommodate all the teeth and the FPMs had a poor long-term prognosis, Case 1 was planned for early extraction of all four FPMs to allow spontaneous space closure from the second molars.
The spaces closed satisfactorily with a good contact point between the second molar and second premolar as seen on the OPT at age 13 (Figure 2).
This patient presented aged 9 years with a Class I incisor relationship, mild crowding in the lower arch and potential crowding of the canines in the upper arch (Figure 3). Case 2 had MIH of all FPMs, the lower FPMs were broken down and the upper FPMs were in a reasonable state.
As extractions were unlikely to be required for alignment in the lower arch and the lower FPMs had a poor long-term prognosis, the lower FPMs were planned for early extraction to allow spontaneous space closure from the second molar.
The upper FPMs were retained as there was more potential for crowding in the upper arch and the upper FPMs were only mildly hypomineralized. Rather than extracting the upper FPMs as compensation, they were monitored in case of overeruption.
Favourable factors for retaining the upper FPMs were present:
At age 12 (Figure 4), the lower FPM spaces closed satisfactorily. As it turned out, there was subsequently sufficient space for the upper canines therefore the upper FPMs did not need to be extracted to facilitate orthodontic treatment and these teeth had not overerupted.
This patient presented aged 10 years with a significant Class II division 1 incisor relationship, 10-mm overjet, on a severe Class II skeletal base with mild upper and lower crowding. There was advanced breakdown associated with the lower FPMs, and the upper FPMs were mildly affected by MIH (Figures 5 and 6).
As extractions were unlikely to be required in the lower arch, and the lower FPMs were of poor prognosis, early extraction of the lower FPMs was planned to allow space closure.
The upper FPMs were maintained in case space was required for alignment and/or overjet reduction if the functional appliance was unsuccessful. As it happened, the overjet was treated with a functional appliance and upper extractions were not required. The lower FPM extraction space closed spontaneously as seen in the OPT aged 13 (Figures 7 and 8).
This patient presented aged 11 years with a Class II division 1 incisor relationship, a slightly increased overjet of 5 mm, well-aligned upper and lower arches, heavily restored FPMs, and carious LR6 (Figure 9).
Extractions were unlikely to be required for orthodontics and the FPMs were of poor long-term prognosis. A general anaesthetic was planned for early extraction of all four FPMs with the hope of spontaneous space closure.
Not all favourable factors were present, but the clinical presentation dictated the treatment plan and long-term maintenance of the FPMs was undesirable. Although the third molars were present, the patient was 11 and the second molars had partially erupted.
At age 13 years (Figure 10), the extraction spaces in the lower arch were still large following full eruption of the second molars. As spaces close more readily in the upper arch, the extraction spaces in the maxilla were not as large as the mandible.
This patient presented aged 10 years with a Class II division 1 incisor relationship, a 7-mm overjet, sufficient space in the upper and lower arches to accommodate all the teeth, carious UR6, LR6, and LL6, and the UL6 had a large restoration (Figure 11).
Given the poor prognosis of the FPMs, they were planned for early extraction with the aim of spontaneous space closure. The increased overjet was planned to be managed with a functional appliance and there would be no significant space requirements.
In cases such as this, one should always consider managing an impacted UR6 with removal of the URE. However, where the upper 6s are of poor prognosis there is no option but to extract the 6s and manage the malocclusion and the loss of space in the upper arch with orthodontic appliances. Functional appliances are often the first choice to address the Class II relationship or distal movement of the upper buccal segments and class II mechanics may be necessary to provide space or reduce the overjet.
Not all favourable factors were present, but the clinical presentation dictated the treatment plan and long-term maintenance of the FPMs was undesirable. Although the patient was 10 years old and the second molars were yet to erupt, there was no visible sign of the third molars developing.
As space closes more readily in the upper arch, the upper extraction spaces closed spontaneously, the OPT at age 14 is shown in Figure 12. However, spontaneous space closure is less likely in the mandible and there was still significant spacing in the lower arch which is challenging to fully close in fixed appliances and retain.
Planning the management of poor prognosis FPMs is complex. No two cases are the same and there are numerous factors to consider. Ideally, these children would be managed by an orthodontist and a paediatric dentist with experience in early interceptive occlusal guidance, but these services are not always available and therefore, the general dentist should have an understanding of what features to look out for.
When assessing these cases, the clinician has to make a best-guess prediction of future space available, prognosis of compromised teeth, likelihood of spontaneous space closure and whether the child will be amenable to orthodontic treatment. Although the predictive factors discussed in this article may guide decision-making, they cannot be fully relied upon. Even with ideal factors present, space closure may not occur and the child may be left be with gaps in their dentition. The patient and parent need to accept this as part of the consent process. Poor prognosis FPMs may be retained for their extraction space to be used to treat future crowding; however, the child may then grow favourably and not require extractions. This would leave the child having to maintain a poor prognosis FPM indefinitely.
As part of early interceptive management of FPM's communication of risks must be carefully discussed and documented, and informed consent secured by all parties. Each patient is an individual and although there are guiding principles that lead us to the most strategic treatment plan none can be implemented without the agreement of the patient and their guardians.
