Comparison of Molar Distalization Devices in a Treatment of Malocclusion Class II: Finite Element Analysis

Malocclusion Class II is a poor-bite condition when the lower first molar situates more posteriorly than the upper first molar. To restore the normality of bite condition, the upper molar is often moved distally using an orthodontic device. The objective of this study was to predict and compare the outcomes of two different orthodontic devices both equipped with miniscrews. The first device, called a buccal mini-implant, has miniscrews placed on the alveolar bone on the buccal surface. The second device, called an indirect palatal miniscrew anchorage and distalization appliance or iPANDA, has miniscrews inserted along the midline of the palatal bone. For comparison purpose, a three-dimensional (3D) model of both devices was virtually attached to a 3D model of the upper teeth with maxillary bone and periodontal ligament. A force of 200g was applied through the devices to simulate a recommended distalization force. Teeth displacement, stress in both miniscrews and surrounding bone, and micromotion at miniscrew-bone interface were measured using finite element method. The findings show that the iPANDA device led to a higher molar distalization and higher micronmotion compared to the buccal mini-implant device. Stress obtained from the iPANDA device was also found to be higher, however, it was relatively too small to damage both the miniscrew and surrounding bone.