Evaluation of canine distalization with orthodontic clear aligner technique: A three-dimensional finite element analysis

Lately, in orthodontic treatments, the use of clear aligners for correction of malocclusions has become prominent due to their intrinsic advantages such as esthetics, comfort, and easy of use. In this finite element study, it was aimed to examine the stress distribution and displacement amounts for clear aligner and teeth, caused by the ellipsoid and vertical horizontal attachment and four different thicknesses of aligner used in the canine distalization with the clear aligner technique. In the study, a three-dimensional finite element model including maxillary teeth, clear aligners, attachments and periodontal ligament structures was created. A total of 8 scenarios were created by modeling ellipsoid and vertical horizontal attachments placed on the canine tooth and 0,5 mm, 0,625 mm, 0,75 mm, 1 mm aligner thicknesses. Clear aligners were activated 0,25 mm in all scenarios. With activation, tipping movement occurred in the canine tooth in both attachment types following the application of the clear aligner. It was observed that the distopalatal rotation degree of canine in scenarios with ellipsoidal attachment was higher than vertical horizontal attachment. With the enhancement of the aligner thickness, the amount of force on the canine and palatal tipping of incisors increased. According to the results of our study, there was no difference between the effects of two different attachment types on the parallel movement during distalization, the amount of force acting on the canine tooth increased with the enhancement of the aligner thickness, and it has been determined that undesirable movement may occur especially in the incisors.