Abstract
BACKGROUND: Angle Class II malocclusion typically presents with overbite, distal molar relationship, and crowding of the upper anterior teeth. The distal movement of the maxillary molars is considered an optimal treatment strategy, as it can circumvent the need for orthodontic extraction. Clear aligners are currently used for molar distalization. However, this approach is not without its limitations, including the loss of anterior tooth anchorage and an extended treatment duration. To address these issues, this study introduces a novel molar distalization appliance. A clinical randomized controlled trial will compare the efficacy of this appliance with clear aligners, specifically assessing differences in the rate of tooth movement. METHODS: This study will recruit 30 patients aged 18-35 with Angle Class II malocclusion, characterized by distal molar relationship, mild to moderate crowding, or protrusion of anterior teeth. Patients will be randomly divided into two groups: the experimental group using a novel molar distalization appliance, and the control group using clear aligners for molar distalization. Both groups will use orthodontic miniscrews as an anchorage, with elastic traction for molar distalization. Cone-beam CT and digital dental models will be collected before orthodontic intervention and after molar distalization for all samples. This study will register pre- and post-treatment images using maxillary bone structures and then analyze three-dimensional tooth movement. The study will further calculate the distance of molar distal movement per unit time as the tooth movement rate and compare whether there is a difference between the experimental and control groups. DISCUSSION: This randomized controlled trial will serve as evidence that the novel molar distalization device, compared to clear aligners, whether offers advantages such as shorter treatment duration and superior control of tooth movement. It can provide a novel method for orthodontic clinical treatment of patients with Angle Class II malocclusion. TRIAL REGISTRATION: ClinicalTrials.gov ChiCTR2300069122. Registered on 7 March 2023.