Clear Aligners vs Fixed Appliances for Molar Distalization Using Infrazygomatic Crest Screws

TC Erciyes University37 enrolled

Overview

This study compares three different methods of moving upper back teeth backward (distalization) to create space for crowded or protruding teeth, all supported by small temporary screws placed in the cheekbone area (infrazygomatic crest screws). Participants were randomly assigned to one of three treatment types: traditional fixed braces (Pitts21 system), Invisalign clear aligners, or ClearCorrect clear aligners. The study measures how effectively each method moves the back teeth, how long treatment takes, and how comfortable and practical each method is for patients. The goal is to help orthodontists and patients choose the most effective and efficient treatment option for this type of tooth movement.

This prospective randomized clinical trial included 35 subjects aged 13-18 years with skeletal Class I, dental Class II malocclusion, randomly allocated to Pitts21 fixed appliance (n=12), Invisalign (n=12), or ClearCorrect (n=11) treatment groups. Unilateral or bilateral infrazygomatic crest (IZC) miniscrews were placed in all subjects, and distalization forces were applied via intraoral elastics. Lateral cephalometric radiographs and digital dental models (acquired with a 3Shape TRIOS 3 intraoral scanner) were obtained at the start (T0) and end (T1) of distalization to assess skeletal, dental, and soft tissue changes. Patient-reported outcomes were also collected, including pain (Visual Analog Scale) and anxiety (Çapa Anxiety Scale). Data were analyzed using IBM SPSS v23 and R 4.4.1; normality was assessed with the Shapiro-Wilk test. Between-group comparisons used one-way ANOVA or the Kruskal-Wallis H test, and within-group comparisons over time used paired t-test, Wilcoxon, repeated measures ANOVA, or Friedman test. Group×time and group×tooth interactions were evaluated using Generalized Estimating Equations and Robust Mixed ANOVA, with Bonferroni, Games-Howell, or Holm corrections applied for multiple comparisons.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Interventions

Pitts21® fixed applianceDEVICE

Fixed orthodontic brackets (Pitts21 system) used for maxillary posterior distalization, anchored with infrazygomatic crest miniscrews and intraoral elastics.

Invisalign® Clear AlignersDEVICE

Clear aligner system (Invisalign) used for maxillary posterior distalization, anchored with infrazygomatic crest miniscrews and intraoral elastics.

ClearCorrect Clear AlignersDEVICE

Clear aligner system (ClearCorrect) used for maxillary posterior distalization, anchored with infrazygomatic crest miniscrews and intraoral elastics.

Eligibility

Sex: ALLMin age: 13 YearsMax age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Skeletal Class I (ANB angle 0-4°), dental Class II malocclusion treatable with molar distalization * Need for unilateral or bilateral distalization of the first molars in the range of 2-4.5 mm * Chronological age between 13 and 18 years, regardless of skeletal age * Normal or hypodivergent growth pattern (SN-GoGn \< 39°) * Mild to moderate maxillary crowding (less than 6 mm) and minimal or no mandibular crowding (less than 3 mm) * No previously extracted maxillary teeth, excluding third molars * Erupted permanent second molars * Good oral hygiene * Healthy periodontal tissues Exclusion Criteria: * Need for orthodontic tooth extraction or functional appliance therapy * Presence of systemic disease * Congenital or acquired craniofacial deformity involving the condyle or mandible * Poor patient cooperation * History of allergy to any metal * Pre-existing root resorption prior to treatment * Previous orthodontic treatment * Abnormal position, depth of impaction, or close proximity to adjacent anatomical structures (sinus, neurovascular structures) of the maxillary third molar that would make its surgical extraction risky

Outcomes

Primary Outcomes

Amount of Maxillary Posterior Tooth Distalization

The amount of distalization of the maxillary premolars and molars (U4, U5, U6, U7) was measured in millimeters using three-dimensional digital dental model analysis, comparing pre-treatment (T0) and post-distalization (T1) records.

Time frame: From the date of infrazygomatic crest miniscrew placement and initiation of distalization force (T0) until the end of the active distalization phase (T1), assessed up to 13 months

Secondary Outcomes

Total Distalization Duration

The total duration of the distalization phase, calculated as the time interval between the start of force application (T0) and the completion of active distalization (T1).

Time frame: From the date of miniscrew placement and start of distalization force (T0) until the date of completion of active distalization (T1), assessed up to 13 months