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Infra-occluded deciduous molars can pose a great challenge to clinicians. The management and treatment of a severely infra-occluded tooth often requires a multidisciplinary team (MDT) approach. This case report demonstrates the effective management of a 7-year-old girl who presented with a severely infra-occluded maxillary deciduous second molar. It highlights the importance of early diagnosis and appropriate intervention to help prevent further disruption to a patient's occlusal development. Following removal of the submerging deciduous molar, an upper sectional (2x4) fixed appliance was used to recreate sufficient space for the developing premolars and correct the occlusal discrepancies caused as a result of the infra-occlusion.
CPD/Clinical Relevance: A novel approach to managing an infra-occluded deciduous molar and correcting the associated space loss due to its submergence is described and the benefits of early MDT intervention are highlighted.
Article
Infra-occlusion, also known as submergence, is a term used to describe a tooth that fails to continue to erupt vertically and becomes positioned below the occlusal plane following the continued growth of the surrounding dentition.1 The most common cause of infra-occlusion is ankylosis.2 This can lead to the delayed exfoliation of primary teeth and affect the occlusal development of the permanent dentition. There are two main theories for ankylosis occurring: first, owing to local clinical factors, and secondly owing to genetic predisposition.3 Infra-occlusion is often diagnosed clinically; however, it is important to carry out appropriate radiographic investigations to rule out any abnormal pathology and to confirm the presence of the permanent successors. Congenitally missing premolars are commonly associated with infra-occluded deciduous molars.4 The incidence of an infra-occluded primary tooth with a missing permanent successor has been reported at 12.9%.5 The reported prevalence of infra-occlusion varies enormously between 1% and 35%.6,7 Kurol et al reported infra-occlusion prevalence at 9%.8
There are a number of clinical features associated with infra-occluded teeth that have orthodontic implications, including tipping of adjacent teeth, lateral open-bites, localized or generalized loss of arch length and incomplete alveolar process development.1,9,10 The degree of infra-occlusion is measured by how far the occlusal surface is below the occlusal plane of the adjacent teeth. This has been classified as being slight, moderate or severe.6 Severe infra-occlusion is where the occlusal surface of the tooth is below the interproximal margin of the adjacent teeth. If ignored, a severely submerged deciduous tooth can lead to caries and resorption of the proximal surface of the adjacent teeth. It can also cause space loss, impaction of adult teeth and in some cases centreline shifts. It is essential to diagnose any infra-occlusion as early as possible to prevent derangement of the occlusion, which can be costly to fix in terms of time and financial implications for the health service or the patient. Early diagnosis allows for adequate time to plan for any necessary treatment that could involve the surgical removal of the tooth, alongside orthodontic intervention.2 Early diagnosis and treatment planning has been shown to facilitate simpler treatment plans.11 If infra-occlusion of the deciduous dentition is suspected, the dentist should employ a period of monitoring using clinical measurements, high-quality intra-oral photographs or radiographs where necessary. Once worsening submergence has been confirmed, the patient should be referred onwards to an appropriate specialist for further management.
Case report
A 7-year-old girl was referred by her general dental practitioner to the orthodontic department with a submerging deciduous maxillary second molar. There was no family history of any dental anomalies and the patient was medically fit and well. Her main complaint was that she could see her ‘baby tooth was sinking’ (Figures 1a–c).
Figure 1.
(a) Frontal intra-oral photograph taken at initial assessment. (b) Right lateral intra-oral photograph taken at initial assessment. (c) Left lateral intra-oral photograph taken at initial assessment. (d) Upper occlusal photograph showing the degree of infra-occlusion pre-treatment
The patient presented in the early mixed dentition with a symmetrical appearance on a Class 1 skeletal base with normal facial proportions and an average lip line. Intra-orally, she presented with a Class 1 incisor relationship and Class 1 buccal segments with a severely infra-occluded maxillary deciduous second molar in the upper right quadrant (Figure 1d). There was obvious mesial tilting of the adjacent maxillary molar tooth distal to the submerging deciduous molar. The first deciduous molar had tilted distally as a result of the infra-occlusion.
Radiographic assessment
A panoramic radiograph confirmed the presence of the developing permanent dentition with no signs of hypodontia. Both developing maxillary premolars in the upper right quadrant were present with a degree of premolar ‘stacking’ (Figure 2). The infra-occluded maxillary right second deciduous molar showed some root resorption; however, it was submerged and becoming impacted against the distal aspect of the adjacent molar tooth. This radiograph confirmed the submergence was worsening when compared with a previous radiograph taken by the referring practioner 7 months prior to the initial assessment OPT (Figure 3).
Figure 2. OPT radiograph from referring practitioner.Figure 3. OPT radiograph taken at initial assessment on 21 December 2016.
Treatment plan and rationale
Full records were taken along with the necessary radiographs prior to an assessment with a multidisciplinary team. Following the consultation, the patient and parents were consented for the following treatment:
Removal of the infra-occluded deciduous molar under general anaesthesia and fit of a band and loop to the maxillary right first molar to act as a space maintainer shortly after the extraction (within a 2-week period).
Provision of an upper fixed orthodontic appliance to create space for the developing premolars to erupt, and to upright the adjacent teeth.
Prior to commencing treatment, the patient was reminded they would be expected to demonstrate an excellent level of oral hygiene throughout treatment.
Treatment progress
Initially, a band and loop space maintainer was fitted to the maxillary right first molar following the removal of the URE (Figure 4). It was discussed at the planning stage that there was already a loss of space; however, the patient and parents were reluctant to embark upon complex orthodontic treatment at this stage. The space maintainer was therefore used to reduce anxiety towards treatment as well as hold what little space remained after extraction. A panoramic radiograph was taken 3 months after the removal of the URE which showed positive development of the UR5 (Figure 5). Once the patient had become comfortable with the space maintainer and the orthodontic environment, an upper 2x4 fixed appliance was placed on 12 February 2018 with an initial round 0.016 Sentalloy nickel–titanium archwire (GAC) with stainless steel tubing bilaterally (Figure 6). After 2 months, the teeth began levelling and aligning and a 18x25 Neo-Sentalloy nickel–titanium archwire (GAC) placed, again with protective stainless steel tubing to prevent wire distortion and subsequent escape of the wire from the terminal molar tube. Space opening was started using push coil mechanics on a rectangular 19x25 stainless steel archwire around 4 months into treatment (Figure 7). Once 7 mm of space was created, it was maintained, again using the protective stainless steel tubing. An OPT radiograph taken 5 months into the fixed appliance treatment confirmed the UR6 had uprighted and the UR4 and UR5 had a adopted a more normal path of eruption (Figure 8).
Figure 4. Band and loop space maintainer fitted to UR6.Figure 5. OPT radiograph (taken 1 year after initial OPT) demonstrating space maintenance and positive development and migration of UR5.Figure 6. Upper occlusal photograph taken after initial bond-up with MBT brackets and 0.016 nickel–titanium wire. Protective stainless steel tubing placed bilaterally.Figure 7. Upper fixed appliance with push coil between UR2 and UR6 to start opening space.Figure 8. The mid-treatment OPT radiograph, taken 25 July 2018, with the upper appliance in situ shows both UR4 and UR5 adopted a more normal path of eruption and the UR6 uprighted well. All four third molars were now developing.
After only 17 months of upper fixed appliance treatment, the appliance was removed (Figure 9). The URD exfoliated naturally and both upper premolars had erupted in their normal position.
Figure 9.
(a) Upper occlusal view at debond. (b) 1-month post treatment frontal intra-oral view. (c) 6-month post treatment upper occlusal view. (d) 1-month post treatment right lateral view. (e) Pre- and post-treatment frontal extra-oral views. A happy patient post treatment.
At the 6-month review following the removal of the upper fixed appliance, both of the maxillary right premolars had erupted into position and the occlusion was settling well. We expected the right lateral open bite to close naturally as the patient grows and the patient was to be kept under review to ensure that this occurred. The patient was also under review given the slight submergence of the LRE, which did not require active intervention at that stage. Both parents and the patient were extremely happy with the result. It appeared likely that future orthodontic treatment may not be required (Figure 10).
Figure 10. Two years post debond. (a) Front. (b) Right. (c) Left. (d) Upper. (e) Lower.
Discussion
General dental practitioners are ideally placed to identify developmental anomalies such as infra-occlusion.1 The literature states that infra-occlusion tends to occur bilaterally and more commonly affects the mandibular deciduous molars.6,8 The prevalence of infra-occlusion of maxillary deciduous molars is considered to be much lower, approximately 3–8%.12 Most infra-occluded primary molars that have a permanent successor will exfoliate naturally. However early detection and monitoring of an infra-occluded primary tooth is essential to help prevent future occlusal problems. The main goal of treatment when managing an infra-occlusion where the permanent successor is present is to facilitate the normal eruption of the successor.
Conclusion
This case report describes effective management of a severely infra-occluded tooth and the benefits of a multidisciplinary approach in early correction of the associated malocclusion for the patient. The orthodontic technique used in this case demonstrates the simple and cost-effective method of treating a case of infra-occlusion safely.
