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

Evaluation of the Treatment Effects of Different Clear Aligner and Fixed Appliance Systems in Maxillary Posterior Distalization Using Infrazygomatic Crest Screws: An In-Vivo Randomized Clinical Study

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.

Study Overview

• Status: Completed
• Conditions: Angle Class 2 Malocclusion
• Intervention / Treatment: Device: Pitts21® fixed appliance; Device: Invisalign® Clear Aligners; Device: ClearCorrect Clear Aligners

Detailed Description

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
• Enrollment (Actual): 37
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Kayseri, Turkey (Türkiye), 38000
    • Erciyes University, Faculty of Dentistry, Department of Orthodontics

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Group A ( Pitts21® Fixed Appliance ); Participants received maxillary posterior distalization using the Pitts21® fixed orthodontic appliance system, anchored with infrazygomatic crest (IZC) miniscrews and intraoral elastics for distalization force.	Device: Pitts21® fixed appliance; Fixed orthodontic brackets (Pitts21 system) used for maxillary posterior distalization, anchored with infrazygomatic crest miniscrews and intraoral elastics.; Other Names: Fixed orthodontic bracket system
Experimental: Group B ( Invisalign® clear aligners); Participants received maxillary posterior distalization using Invisalign® clear aligners, anchored with infrazygomatic crest (IZC) miniscrews and intraoral elastics for distalization force.	Device: Invisalign® Clear Aligners; Clear aligner system (Invisalign) used for maxillary posterior distalization, anchored with infrazygomatic crest miniscrews and intraoral elastics.; Other Names: Invisalign Clear Aligner System
Experimental: Group C ( ClearCorrect® clear aligners); Participants received maxillary posterior distalization using ClearCorrect® clear aligners, anchored with infrazygomatic crest (IZC) miniscrews and intraoral elastics for distalization force.	Device: ClearCorrect Clear Aligners; Clear aligner system (ClearCorrect) used for maxillary posterior distalization, anchored with infrazygomatic crest miniscrews and intraoral elastics.; Other Names: ClearCorrect Clear Aligner System

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	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 Outcome Measures

Outcome Measure	Measure Description	Time Frame
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).	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

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Distalization Efficacy in Clear Aligner Groups	Distalization efficacy was calculated as the ratio of achieved to planned tooth movement (Efficacy = Achieved/Planned × 100), based on digital treatment planning, for the Invisalign and ClearCorrect groups.	From treatment planning (T0) until the end of active distalization (T1), assessed up to 13 months
Infrazygomatic Crest Miniscrew Success Rate	The success rate of infrazygomatic crest miniscrews used for anchorage was recorded, defined as the proportion of miniscrews remaining stable and functional throughout the distalization period without requiring replacement.	From the date of miniscrew placement until the end of active distalization, assessed up to 13 months
Cephalometric Skeletal, Dental, and Soft Tissue Changes	Skeletal, dental, and soft tissue changes were assessed using lateral cephalometric radiographs, comparing measurements obtained at the beginning (T0) and end (T1) of distalization.	From the date of miniscrew placement and start of distalization force (T0) until the end of active distalization (T1), assessed up to 13 months
Rotation of Premolars and Molars During Distalization	Changes in the rotational position of the maxillary premolars and molars (U4-U7) were measured using digital dental models, comparing T0 and T1 records.	From T0 to T1, assessed up to 13 months
Mesiodistal Tipping of Premolars and Molars During Distalization	Changes in mesiodistal crown angulation (tipping) of the maxillary premolars and molars (U4-U7) were measured using digital dental models, comparing T0 and T1 records.	From T0 to T1, assessed up to 13 months
Transverse Width Changes in the Maxillary Posterior Region	Changes in transverse arch width at the level of the premolars and molars (U4-U7) were measured using digital dental models, comparing T0 and T1 records.	From T0 to T1, assessed up to 13 months
Pain Level Assessed by Visual Analog Scale	Pain associated with treatment was assessed using the Visual Analog Scale (VAS, 0-10) at multiple time points: day 1, week 1, month 1, month 3, and end of distalization.	From day 1 after miniscrew placement/appliance activation up to the end of active distalization, assessed at 5 time points (day 1, week 1, month 1, month 3, and end of distalization; up to 13 months)
Anxiety Level Assessed by the Çapa Anxiety Scale	Patient anxiety related to treatment was assessed using the Çapa Anxiety Scale at multiple time points: day 1, week 1, month 1, month 3, and end of distalization.	From day 1 after miniscrew placement/appliance activation up to the end of active distalization, assessed at 5 time points (day 1, week 1, month 1, month 3, and end of distalization; up to 13 months)

Collaborators and Investigators

• Sponsor: TC Erciyes University

Study record dates

Study Major Dates

• Study Start (Actual): June 6, 2024
• Primary Completion (Actual): January 12, 2026
• Study Completion (Actual): February 18, 2026

Study Registration Dates

• First Submitted: July 15, 2026
• First Submitted That Met QC Criteria: July 15, 2026
• First Posted (Actual): July 20, 2026

Study Record Updates

• Last Update Posted (Actual): July 20, 2026
• Last Update Submitted That Met QC Criteria: July 15, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Distalization; Fixed orthodontic appliance; Clear aligners; Skeletal anchorage; Infrazygomatic crest miniscrew
• Other Study ID Numbers: TDH-2025-15402

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No