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

July 15, 2026 updated by: Ahmet Yağcı, TC Erciyes University

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

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

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

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
37

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

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

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Amount of Maxillary Posterior Tooth Distalization
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
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

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Total Distalization Duration
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
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

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Distalization Efficacy in Clear Aligner Groups
Time Frame: From treatment planning (T0) until the end of active distalization (T1), assessed up to 13 months
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
Time Frame: From the date of miniscrew placement until the end of active distalization, assessed up to 13 months
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
Time Frame: From the date of miniscrew placement and start of distalization force (T0) until the end of active distalization (T1), assessed up to 13 months
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
Time Frame: From T0 to T1, assessed up to 13 months
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
Time Frame: From T0 to T1, assessed up to 13 months
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
Time Frame: From T0 to T1, assessed up to 13 months
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
Time Frame: 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)
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
Time Frame: 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)
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

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
TC Erciyes University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 6, 2024

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 12, 2026

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
February 18, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
July 15, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 15, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
July 20, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 20, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 15, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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