CROSS-PALATAL ELASTICS FOR ALIGNING BUCCALLY PLACED UPPER SECOND MOLARS
by Drs. Yadav, Upadhyay and Nagaraj

Introduction

It is not unusual to see maxillary second molars erupting in buccoversion because of lack of development in the tuberosity area1. It has been reported that in the maxillary arch, the greatest number of malposed second molars are displaced straight to the buccal2. Additionally, the eruption pattern of the upper second molar shows a tilting of the long axis of the tooth in a mesial-palatal direction. The problem gets further compounded, for the clinician, when a case is in large rectangular finishing archwires and the second molar erupts in 'buccoversion'. In this article, a simple and efficient method to correct upper second molar position is described.

Method

A 'hook' or a 'molar tube' or any other attachment large enough to accept elastics is bonded on the buccal surface of the second molar. Elastics* are engaged from one hook to the other, running across the palate in the transverse plane. (Fig A).The patient is given instructions regarding the usage of the elastics. Equal and opposite forces are exerted by the stretched elastic on both the molars resulting in a palatal movement (Fig B). Clinical situations presenting with only one maligned second molar can be corrected by including the contra lateral normally aligned second molar into the main archwire, while keeping the malposed molar free. Elastics are engaged as described before. In this way the reactive forces are distributed over the entire arch. Clinical examples

Fig. A	Fig. B

Case 1

After extracting all the third molars, a fixed appliance was placed. 'Cross-palatal elastics' were used by this patient to correct the buccally placed second molars. It required 8 weeks to correct the molar positions (Fig C, D).

Fig. C	Fig. D

Case 2

In this patient, the maxillary second molars erupted buccally during treatment. Significant improvement in the molar position was seen after using 'Cross-palatal elastics' for only 4 weeks. (Fig E, F)

Fig. E	Fig. F

Discussion

The technique described not only brings about a palatal crown movement, but also helps to control the amount of buccal root torque. Unlike interarch elastics which might show significant amount of extrusion, Cross-palatal elastics do not cause any extrusive movement of the molars. (Fig G). The other advantages of this technique are: Requires minimal chair time. Can be employed even after termination of orthodontic treatment.

Fig. G

References

Chipman MR. Second and third molars: their role in orthodontic therapy. Am J Orthod 1961: 498-520.

Cureton SL. Second molar biomechanics. J Clin Orthod 1995; 29:500-508.

* 3M Unitek, Monrovia, CA 91016.