Intrusion of over-erupted maxillary first molar using a mandibular removable acrylic bite plate

INTRODUCTION

Patients who have over-erupted molars due to the loss of antagonists are a common clinical finding. To provide prosthetic treatment of the missing teeth, these over-erupted teeth need to be intruded, but molar intrusion is difficult in adults.^[1,2]

To reconstruct the proper occlusion for the posterior dentition and to maintain periodontal health, an interdisciplinary and comprehensive dental treatment is necessary. Correction of the over-erupted molar is a first and essential step before other procedures can be started. Procedures such as orthodontic intrusion, prosthodontic reduction, and surgical impaction have been presented.^[3-8] However, prosthodontic reduction requires endodontic intervention and crown restoration at the expense of tooth vitality, whereas surgical impaction involves an aggressive segmental operation.

Grinding the over-erupted tooth is quick and easy, but in severe cases, the teeth need to be treated endodontically.^[9]

Various methods of molar intrusion using micro-implants, mini-plates etc., have been advocated.^[10-12] We have devised a simplified method of molar intrusion using a removable lower acrylic bite plate.

CASE REPORTS

An adult patient aged 25 years reported prosthetic department seeking replacement of missing lower right first molar. Patient was referred to orthodontics, as over-eruption of upper first molar hampered the proper replacement of missing tooth [Figure 1a-c]. We advocated a simple method of molar intrusion using a removable acrylic plate.

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Figure 1

(a) Intra-oral right view depicting over-erupted maxillary molar. (b) Study model showing over-erupted maxillary molar. (c) Pretreatment Orthopentogram

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PROCEDURE

Upper arch was strapped up using a MBT 0.022 × 0.028” bracket prescription and initial flexible arch wires were ligated.

A lower removable acrylic bite plate was fabricated with posterior bite block occupying the space created by missing lower molar [Figure 2a and b].

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Figure 2

(a) Lower acrylic bite plate. (b) Intra-oral view of bite plate

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The bite block occlusal surface was kept flat in order to apply an even intrusion force onto upper molar. Clasps were embedded in acrylic plate to enhance retention. Patient was instructed about plate placement and was insisted to wear the plate during mastication also.

After 3 months of active therapy, significant intrusion of maxillary molar was observed [Figure 3a and b]. Sagging of palatal cusp of upper molar was not seen, depicting true intrusion. Superimposition of cephalograms showed intrusion of maxillary molar by about 2 mm [Figure 4].

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Figure 3

(a) Intra-oral right view depicting intruded maxillary molar. (b) Study model showing intruded maxillary molar

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Figure 4

Cephalometric superimpositions

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CONCLUSION

Various methods like mini-implants, mini-plates have been used for intrusion of upper molar due to missing lower molar. These methods require an additional step of placing implants or mini-plates. True intrusion of upper molar mostly requires implants to be placed on both buccal and palatal sides. The method advocated here, uses a removable acrylic plate resulting in a true molar intrusion, thus eliminating an additional surgical step of implant placement. The results showed that the biological responses of the teeth and the surrounding bony structures to the intrusion appeared normal and acceptable.