Root Shortening With Three Methods of Upper Front Teeth Retraction

July 29, 2026 updated by: Damascus University

External Apical Root Resorption in Three Miniscrew-Supported Maxillary En-Masse Retraction Mechanics: A Randomized Controlled Trial

External apical root resorption is a possible side effect of fixed orthodontic treatment, particularly in the upper front teeth. This randomized clinical trial was conducted to compare the amount and timing of root resorption associated with three different methods of retracting the upper anterior teeth using miniscrew anchorage. Sixty adult patients with Class II Division 1 malocclusion who required extraction of the upper first premolars were randomly allocated to one of three groups: a bidimensional bracket group, a hybrid dual-section archwire group, or a conventional sliding mechanics group. In all groups, the six upper anterior teeth were retracted together with the support of orthodontic miniscrews. Panoramic radiographs were obtained before treatment, after completion of leveling and alignment, and after completion of en-masse retraction. Root and crown lengths were measured on these radiographs to estimate external apical root resorption during the leveling and alignment phase, during the retraction phase, and over the complete observation period. The study also compared the pattern of resorption among the upper canines, lateral incisors, and central incisors.

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

Orthodontic camouflage treatment of adult patients with Class II Division 1 malocclusion frequently involves extraction of the maxillary first premolars followed by retraction of the upper anterior teeth. Temporary orthodontic miniscrews can provide skeletal anchorage during this stage and allow the six maxillary anterior teeth to be retracted together as one unit. Although these mechanics are widely used, the anterior teeth remain exposed to orthodontic forces during both the initial leveling and alignment phase and the subsequent retraction phase. External apical root resorption is therefore an important biological safety outcome that should be evaluated throughout treatment rather than only after space closure has been completed.

This single-center, three-arm, parallel-group randomized clinical trial was conducted at the Department of Orthodontics, Faculty of Dentistry, Damascus University. Sixty adult patients with Class II Division 1 malocclusion who required extraction-based orthodontic camouflage treatment were allocated equally to one of three treatment groups: a bidimensional bracket group, a hybrid dual-section archwire group, or a conventional sliding mechanics group.

The three approaches differed in the relationship between the anterior brackets and the working archwire. The bidimensional approach used smaller anterior bracket slots with larger posterior slots. The hybrid dual-section approach used a customized archwire with different anterior and posterior cross-sections, while the conventional group used a continuous archwire with a uniform cross-section. These mechanical differences may influence archwire engagement, force expression, and the distribution of forces applied to the roots of the maxillary anterior teeth. Their possible effect on external apical root resorption therefore required direct clinical comparison.

All participants underwent bilateral extraction of the maxillary first premolars, fixed-appliance leveling and alignment, and miniscrew-supported en-masse retraction of the six maxillary anterior teeth. The same general treatment stages and skeletal anchorage concept were used in all groups, while the bracket-slot and archwire configurations varied according to group allocation. Retraction continued until an acceptable overjet and a Class I canine relationship were achieved. Participants were reviewed regularly throughout treatment, and miniscrew-related or other treatment-associated adverse events were recorded.

Digital panoramic radiographs were obtained before orthodontic treatment, at the end of leveling and alignment immediately before retraction, and after completion of en-masse retraction. The maxillary central incisors, lateral incisors, and canines on both sides were assessed individually. Crown length was used as a stable reference to correct for differences in radiographic magnification between time points.

The study was designed to determine whether the three treatment approaches were associated with different amounts of external apical root resorption and to identify the treatment phase during which root shortening occurred. Resorption was therefore evaluated separately during leveling and alignment, during en-masse retraction, and across the complete observation period. This phase-specific design was intended to avoid attributing all root changes detected at the end of retraction to the retraction mechanics alone.

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.
60

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

  • Syria
      • Damascus, Syria, DM20AM19
        • Faculty of Dentistry

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

  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Adults aged 18-30 years.
  • Class II Division 1 dental malocclusion according to Angle classification
  • Mild-to-moderate skeletal Class II discrepancy, with an ANB angle greater than 4° and not exceeding 7°.
  • Overjet ranging from 5 to 9 mm.
  • Presence of all six maxillary anterior teeth.
  • Maxillary anterior teeth fully erupted and with complete root formation.

Exclusion Criteria:

  • Patients with previous orthodontic treatment.
  • Missing permanent maxillary teeth.
  • Active periodontal disease.
  • History of trauma to any maxillary anterior tooth.
  • Previous endodontic treatment of any maxillary anterior tooth.
  • Periapical pathology involving any maxillary anterior tooth.
  • Extensive coronal restorations that could interfere with crown-length measurement.
  • Radiographic evidence of pre-existing root resorption before orthodontic treatment.

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.
Experimental: Bidimensional Bracket Group
Participants will be treated using a bidimensional fixed orthodontic appliance during leveling, alignment, and en-masse retraction.
Procedure: Bidimensional Bracket System
Fixed orthodontic treatment will be performed using 0.018-inch slot brackets from canine to canine and 0.022-inch slot brackets on the posterior teeth. After leveling and alignment, en-masse retraction will be performed on a 0.018 × 0.025-inch stainless-steel archwire using bilateral orthodontic miniscrews and nickel-titanium closed-coil springs delivering 250 g of force per side.
Experimental: Hybrid Dual-Section Archwire Group
Participants will be treated using a hybrid dual-section archwire during miniscrew-supported en-masse retraction.
Procedure: Hybrid Dual-Section Archwire
Fixed orthodontic treatment will be performed using 0.022-inch slot brackets. En-masse retraction will be carried out using a customized stainless-steel archwire consisting of a 0.019 × 0.025-inch anterior section and 0.016 × 0.022-inch posterior sections, with the transitions located distal to the maxillary canines. Bilateral orthodontic miniscrews and nickel-titanium closed-coil springs delivering 250 g per side will be used.
Active Comparator: Conventional Sliding Mechanics Group
Participants will be treated using conventional fixed orthodontic sliding mechanics during miniscrew-supported en-masse retraction
Procedure: Conventional Sliding Mechanics
Fixed orthodontic treatment will be performed using 0.022-inch slot brackets. En-masse retraction will be carried out on a continuous 0.019 × 0.025-inch stainless-steel archwire using bilateral orthodontic miniscrews and nickel-titanium closed-coil springs delivering 250 g of force per side.

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
External Apical Root Resorption of the Maxillary Anterior Teeth
Time Frame: Time 0: before the initiation of orthodontic treatment; Time 1: after the leveling and alignment stage, which occurs within an average of four months, Time Final: after the en-masse retraction stage, which occurs wihtin an averag 12 months.
External apical root resorption was assessed separately for the six maxillary anterior teeth by measuring changes in corrected root length on digital panoramic radiographs using ImageJ software. Crown length was used as a stable reference to correct for differences in radiographic magnification. Root resorption was expressed in millimeters, and the total amount was calculated directly from the initial and final radiographs rather than by adding the interval measurements.
Time 0: before the initiation of orthodontic treatment; Time 1: after the leveling and alignment stage, which occurs within an average of four months, Time Final: after the en-masse retraction stage, which occurs wihtin an averag 12 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.
Damascus University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Mohammad Younis Hajeer, Department of Orthodontics, Faculty of Dentistry, University of Damascus
  • Principal Investigator: Abdulmalek M. H. Almasri, Department of Orthodontics, Faculty of Dentistry, University of Damascus

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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.
July 2, 2025

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.
June 23, 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.
June 28, 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 23, 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 29, 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.
August 4, 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.
August 4, 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 29, 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

Additional Relevant MeSH Terms

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.
  • UDDS-2026-Ortho-03

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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