Effectiveness of Composite Attachments in Controlling Upper-Molar Movement with Aligners.

of accuracy of upper-molar bodily movement with aligners when a distalization movement of at least 1.5mm was prescribed, attributing any significant difference to the use of attachments.6 These observations were made in the horizontal plane; tipping effects were not analyzed. Tipping movements are difficult to control during molar distalization with aligners because of the trays’ limited contact with the tooth surfaces in the direction of force application.8 Gomez and colleagues showed that when an aligner segment was displaced distally without attachments, a clockwise moment and distal inclination were produced on the upper canine.9 Vertical rectangular attachments on the buccal aspects of the molars helped counteract this inclination tendency by producing a countermoment that promoted bodily movement.9 The present case-control study was designed to test the hypothesis that the number of long vertical attachments on the distalizing teeth has no effect on the amount of bodily upper-molar movement achieved with aligner therapy. I nonextraction treatment, upper-molar distalization is often the method of choice to gain 2-3mm of arch space and obtain a Class I relationship.1 To achieve bodily movement, either the applied force must pass through the tooth’s center of resistance or a sophisticated equivalent system of forces and moments must be applied to the molar crown.2,3 Although a systematic study has found aligners to be more effective than fixed appliances in treating mild-to-moderate crowding,4 Brezniak has suggested that bodily movement is not possible with aligners, even when composite attachments are used.5 Recent studies indicate, however, that the forces and moments generated by Invisalign* trays are within the range of orthodontic forces.6,7 Simon and colleagues also reported a high degree