A novel pre-formed distal shoe eruption guidance appliance in chairside management of early loss of primary second molar: a case report

Preserving the primary teeth in the dental arch until they exfoliate is one of the most important aspects of preventive and interceptive dentistry.¹ Premature loss of primary tooth or a group of teeth might lead to wide range of implications.² Loss of space is reported in as high as 51% in prematurely lost first primary molars and 70% in prematurely lost second primary molars.³ A 2016 review found space maintainers to be useful in reducing detrimental effects, such as arch space/tooth size discrepancy, prevention of occurrence of malocclusion, prevention of space loss and consequent malposition of a permanent tooth in that quadrant owing to premature loss of primary second molar in 81% of cases.⁴ A 2020 finite element study found that the presence of a space maintainer significantly reduced the space loss that occurs with eruption of first molars.⁵

When the primary second molar is lost before the eruption of the first permanent molar, intra-alveolar space maintainers are advised, but there are some circumstances in which they are contraindicated, such as in certain medical conditions (e.g. blood dyscrasias, immune suppression, congenital heart disease) and in patients with poor oral hygiene.⁶ In this case report, the clinical management of a deep carious primary mandibular molar with poor prognosis is described using a novel pre-formed distal shoe eruption guiding appliance.

Case report

A 3-year-old girl child who had experienced recurrent pain in the lower right and left molar region of the jaw presented to the paediatric and preventive dentistry department. There was relevant medical history. Extra-oral examination revealed irregularities. On taking a dental history, it was revealed that a pulpectomy had been performed in the right mandibular second primary molar at a private dental clinic 1 month previously.

Clinical intra-oral examination showed a deep carious lesion in the left mandibular second primary molar and the endodontically treated right mandibular second primary molar. The buccal vestibule was swollen and painful on palpation with intra-oral sinus formation near the right mandibular second primary molar (Figure 1) An intra-oral peri-apical radiograph revealed peri-apical and inter-radicular radiolucency with widening of periodontal ligament space of the right mandibular second primary molar. The permanent right first molars displayed Nolla's Stage V of tooth development.⁷ At a further appointment, pulp therapy was completed on the left mandibular second primary molar, followed by a stainless steel crown.

Radiographic investigation showed that the right mandibular second primary molar had a poor prognosis and required extraction owing to recurrent peri-radicular radiolucency and internal root resorption. CBCT was carried out to measure the width and thickness of bone and to rule out any peri-apical and bone pathology (Figures 2 and 3).

Following the investigations, a distal shoe space maintainer appliance was planned. The treatment plan was explained to the patient and parents and consent was obtained. Band adaptations were carried out on LRD.

The decision regarding the length of the horizontal bar was made by checking the space between the distal surface of LRD and mesial surface of LR6 on the intra-operative peri-apical radiograph (IOPA) with a grid. The gingival extension of the appliance was adjusted 1 mm below the mesial marginal ridge of the LR6 using the IOPA with grid (Figure 2).

Extraction of LRE was carried out after administering local anaesthesia (2% lignocaine hydrochloride IP with 1:80,000 adrenaline). The patient was prescribed oral antibiotics for 3 days to reduce wound healing complications and dento-alveolar abscess.

After carrying out the necessary adjustment band cementation was done in LRD using type I glass ionomer luting cement (GC Gold Label, GC Corp, Japan). The distal shoe extension was adjusted using the measured length and inserted into the tube. A minor adjustment was done using a crimping plier. Proper instructions were given to the patient and parents regarding appliance and oral hygiene maintenance (Figure 5).

In this present case, a pre-formed distal shoe space maintainer (e-Distal Shoe Space maintainer, Kids-e-Dental, Mumbai, India) was used (Figure 4). This appliance is made of 316L medical grade stainless steel which is more resistant to corrosion, has higher tensile strength, higher melting point, and is non-magnetic. A pre-formed space maintainer provides the advantages that it can be given in a single appointment, requires less chairside time, is more stable, and removes several steps of impression making and laboratory work. The V-shape extension provides a broad contact area that helps in the stability of the appliance and provides better appliance integrity. This space maintainer provides universal bands with sand-blasted inner surfaces, allowing for better appliance retention and preventing dislodgement.

After 3 days, the patient was recalled to evaluate the wound healing and stability of the appliance.

Meticulous follow-up was carried out at 6-month intervals, with application of 5% sodium fluoride varnish as a preventive measure, to check the integrity of the appliance, eruption status of the permanent molar, and oral hygiene status (Figure 6). At the 12-month follow-up appointment, the patient and her parents were very cooperative and had no complaints. The space maintainer was well-accepted by the child and her parents (Figure 7).

Further follow-ups were to be carried out at 6-monthly intervals until the permanent mandibular first molars had erupted. Following this, the pre-formed distal shoe would be replaced with an appropriate space maintainer, if required.

Discussion

The premature loss of primary teeth can lead to disturbances in normal exfoliation pattern and loss of arch length.⁸ Dental treatment of patients with early loss of multiple primary molars is a crucial for paediatric dentists because these teeth play an important role in preserving leeway space.⁹

If the second primary molar is lost before the eruption of the permanent first molars, a space maintainer must be placed to guide the emergence of the permanent first molars into the right position and prevent the mesial ‘drifting’ of the permanent molar.²

Distal shoe appliance is not usually given in the maxillary arch since the permanent first molars initially emerge distally from the arch until the cusp tip enters the mouth before swinging mesially to hit the distal surface of the primary second molar. However, in the mandibular arch, the distal crown surface of the primary molar is crucial for guiding the eruption of the first permanent molar.² Premature loss of primary mandibular second molars results in severe space loss and mesial migration of permanent molar due to its upwards, forwards and mesial eruption pathway.^1,2 Distal shoe space maintainers are frequently and successfully used in situations where the primary second molar is lost before eruption of permanent first molar.¹⁰ However, it might not be necessary until the first permanent molar has begun to actively erupt.¹¹

Contraindication of this appliance is poor parent and patient compliance, congenitally absent first permanent molar, and multiple loss of teeth leading to inadequate abutments. Other contraindications are, in a patient with a history of systemic illness such as kidney disease, rheumatic fever, low resistance to infection, juvenile diabetes, or certain blood diseases and for patients with congenital heart defects who need prophylactic antibiotics.¹²

As the design is non-functional, and placement has to be precise, this appliance needs to be routinely monitored for the eruption of the permanent mandibular first molar both radiographically and clinically.

Conclusion

Pre-formed distal shoe appliance can be used in cases where primary second molars are lost before the eruption of permanent first molar because it maintains space and helps in guiding the eruption pathway for first permanent teeth. Its design can withstand the force of eruption since it offers broad contact and prevents lingual or buccal deviation. However, regular patient follow-ups are necessary for this modified design to be effective. More clinical study is needed to determine its application in paediatric dentistry.