Functional Space Maintainer - A Case Series

Introduction

Premature loss of primary teeth is a common problem which results in disruption of arch integrity and adversely affects the proper alignment of permanent successors.¹ This is attributed as a common aetiological factor for malocclusion with about 51% of the prematurely lost first primary molars and 70% of prematurely lost second primary molars resulting in loss of space and a consequent malposition of a permanent tooth in that quadrant.² An immediate placement of a space maintainer is the safest way to eliminate or reduce some of these difficulties.³ Numerous types of space maintainers can be used depending on the child’s dental and chronological age, involved dental arch, missing teeth, type of dentition and the needs and compliance of the patient. Occlusion is also a factor of paramount importance while determining the type of space maintainer.⁴

Traditionally, band and loop space maintainer is most commonly used space maintainer. It is a unilateral, fixed, non-functional & passive space maintainer. Band and loop is an effective space maintainer for unilateral loss of single tooth in buccal segments and is indicated for unilaterally or bilaterally lost, maxillary or mandibular primary molars.² Similarly, lingual arch space maintainer is commonly used for premature bilateral loss of mandibular primary molars, post the eruption of permanent incisors. However, both these appliances do not restore masticatory function of the missing tooth and does not prevent the continued eruption of opposing tooth. When there is premature loss of primary teeth in a very young patient, the clinician must consider the masticatory needs and subsequent supra-eruption of the opposing teeth while deciding the appliance. This paper discusses three cases, two fixed functional band and loop space maintainer and a fixed functional lingual arch space maintainer to replace the missing teeth and restore the masticatory function.

Case Presentation

The patients included in the study had teeth indicated for extraction and the permanent tooth bud in Nolla’s stage 6 or 7 with more than 3 mm bone coverage. Tanaka-Johnston, Moyer’s and Huckaba model analyses were done in all the cases to assess the space available. All the cases included in the study had sufficient space and were indicated for space maintenance. Moreover, the patients did not have crowded arches or any gross skeletal malocclusion and no relevant medical history was noted. The parents were explained regarding all treatment options. The advantages and limitations of functional space maintainer were explained. An informed consent was obtained and post-insertion instructions were given. All the patients had fair oral hygiene and were in an age group to be able to effectively follow the oral hygiene measures by themselves. Moreover, patients had an additional complaint of loss of function which mandated the need for replacement of teeth.

Case 1

An eight-year-old male patient reported to the department for a routine dental check-up. On clinical examination, 54 was grossly decayed with grade II mobility. On radiographic examination, 54 and 74 revealed poor prognosis with bone loss with external resorption in palatal and mesio-lingual roots of 54. Hence, 54 and 74 were indicated for extraction. All the other carious teeth were restored with glass ionomer cement. Conventional band and loop was placed with respect to 74. On the follow up visit after one month, patient reported to be very satisfied with the functional space maintainer than the traditional band and loop with respect to the ease of mastication and aesthetics.

Case 2

A female patient who was eight years old reported to the department for a dental evaluation. On clinical examination, 64 was grossly decayed with grade 2 mobility. Proximal (distal) caries was seen with respect to 64 and (mesial) 65. On radiographic examination, 64 revealed poor prognosis with extensive bone loss and furcation involvement, with external resorption in palatal and distobuccal roots of 64 and internal resorption in the mesiobuccal root. Owing to this, 64 was indicated for extraction and 65 for restoration. Model analysis was done to assess the space available, followed by placement of a fixed functional band and loop space maintainer with respect to 64.

Case 3

A female patient who was eight years old had reported to the department with complaint of pain with respect to lower right back tooth region for past 10 days. On clinical examination, there was deep dentinal caries with respect to 74, 75, 84, 85; root stump with respect to 65 and dental caries affecting 73 and 83. Patient’s guardian was explained about the treatment plan and was unwilling for pulp therapy. Therefore, extraction of 74, 75,84,85 followed by space maintainer was advised. Model analysis revealed adequate space for space maintenance. A functional lingual arch appliance was planned for the patient to aid in mastication and to avoid supraeruption of opposing teeth. A functional lingual arch space maintainer was fabricated after banding 36, 46 and cemented.

Technique for fabrication of functional space maintainer

In the first step, banding was done followed by routine impression making and pouring of cast. In the same appointment, another impression was made without the bands. Fabrication of the loop, soldering the loop, finishing and polishing of the space maintainer was done in the same manner as for conventional band and loop. The fabricated band and loop was placed in the second cast. An acrylic tooth was used as a pontic. It was trimmed and customised to fit in between the loop to replace the missing tooth/teeth. Occlusion was examined with the opposing cast after stabilising the acrylic tooth with modelling wax. In the final step, pontic was acrylised to the loop of the space maintainer using cold cure acrylic material. Finishing and polishing was done for the appliance after removing it from the cast and then was checked in patient’s mouth. After correcting any occlusal interferences, the appliance was cemented.  

Patient was recalled after one month for the first review and every three months for subsequent reviews. Parents were emphasised regarding the importance of recall visits as the eruption of permanent teeth will be masked by the acrylic component. Oral hygiene instructions were given to the patient and parent and the need for extra care was highlighted. Fluoride application was planned for subsequent visits.

Discussion

The untimely loss of primary teeth might result in muddled vertical and horizontal occlusal relationships in both primary and permanent dentitions. Owing to this, it is essential to maintain the space created by primary teeth until the eruption of permanent successors.⁵ Due to various factors, premature loss of primary teeth remains to be a prevailing problem which in turn results in disrupting the arch integrity and untowardly changing the alignment of permanent successors. Immediate provision of a space maintainer is the safest way to eliminate or reduce some of these difficulties.⁶ Space maintainers can either be removable or fixed, functional or non functional and unilateral or bilateral. The selection of the appliance is tailored depending upon the need of the situation. Fixed space maintainers, if properly designed, are not harmful to the oral tissues, require less patient compliance than removable space maintainers, and are more suitable for longer periods of space maintenance.⁷ Band and loop space maintainer and lingual arch space maintainer are two of the most commonly used space maintainers owing to their vast application in different clinical scenarios, ease of fabrication, less chair side time and patient acceptance.⁸ However, both these space maintainers lack in providing masticatory function and do not prevent supra-eruption.

The present case series shows the incorporation of a pontic to replace missing teeth in the conventional appliances. The advantages of this appliance are prevention of supra-eruption of opposing teeth, aiding in masticatory function, prevention of abnormal tongue habits and less chances of wire distortion or slippage due to distribution of occlusal forces on the pontic.¹ The drawback associated with the use of this appliance is the need for extra care in maintainence of hygiene under the acrylic flange. Hence, patient selection plays a vital role in determining the success of the appliance and must be avoided in patients with very poor oral hygiene and those with low compliance. However, if it does happens, the appliance can be temporarily de-banded until the tissue heals.⁹ Additionally, the eruption of permanent tooth cannot be visualized directly due the acrylic component. Therefore, long-term and frequent follow-ups using radiographs should be done. Removing the appliance periodically for clinically inspecting the tissue under the appliance and for sign of eruption of permanent successor should be undertaken.1 The appliance can be recemented after the clinical inspection. Parents/ caregivers must be made aware regarding the drawbacks of the appliance and the importance of future review visits must be emphasized. The patients in the present paper were recalled after one and three months for follow up and patients did not report any tissue irritation or discomfort with the appliance while eating. The appliance did not cause food lodgment or interfere with oral hygiene maintenance of the patient.

Fixed space maintainers are commonly used in unilateral and/or bilateral premature loss of primary teeth. However, these conventional fixed space maintainers do not aid in mastication and prevention of supra-eruption. Functional fixed space maintainers can be planned to aid in function, for patients who have to wear the appliance for longer periods and if the parents insist on replacement of missing teeth. Though frequent follow up is needed to monitor the erupting permanent successor, functional space maintainers can be appraised as good alternative to conventional space maintainers.