Effect of Proximal Segment Positioning on Condylar Remodeling

August 6, 2026 updated by: Bezmialem Vakif University

The Effect Of Different Proximal Segment Positioning Methods On Postoperative Condylar Remodeling in Patients Undergoing Bimaxillary Orthognathic Surgery

This study aims to evaluate postoperative condylar remodeling in patients undergoing bimaxillary orthognathic surgery by comparing two different proximal segment positioning techniques used during mandibular osteotomy. Condylar remodeling will be assessed using preoperative, immediate postoperative, and 6-month postoperative computed tomography (CT) scans together with clinical findings.

Study Overview

Status

Status

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

Conditions

Conditions

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Intervention / Treatment

Intervention / Treatment

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Detailed Description

Bilateral sagittal split ramus osteotomy (BSSO), performed as part of bimaxillary orthognathic surgery, requires accurate positioning of the proximal mandibular segment to achieve postoperative skeletal stability and preserve temporomandibular joint function. During mandibular repositioning, discrepancies at the inferior border of the mandibular segments may be managed either by rotating the proximal segment to achieve inferior border alignment or by leveling the inferior border without rotating the proximal segment. The influence of these different positioning strategies on postoperative condylar remodeling has not been fully elucidated.

The aim of this study is to compare postoperative condylar remodeling between patients treated with proximal segment rotation for inferior border alignment and those treated with inferior border leveling without proximal segment rotation.

Condylar remodeling will be evaluated using computed tomography (CT) images obtained preoperatively, immediately after surgery, and at the 6-month postoperative follow-up. Radiological findings will be analyzed together with clinical outcomes to assess changes in condylar morphology and postoperative adaptation. The results of this study are expected to provide evidence regarding the effect of different proximal segment positioning methods on condylar remodeling and may contribute to optimizing surgical techniques in orthognathic surgery.

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 (Estimated)

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.
40

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 Contact

Study Contact

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Study Locations

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
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  1. Patients with skeletal Class III dentofacial deformity scheduled to undergo bimaxillary orthognathic surgery.
  2. Age between 18 and 65 years.
  3. Patients who have completed preoperative orthodontic treatment.
  4. Patients in whom the mandibular distal segment demonstrates a maximum counterclockwise rotation of 4° after bilateral sagittal split osteotomy (BSSO) when positioned in the final planned occlusion.

Exclusion Criteria:

  1. History of temporomandibular joint surgery, orthognathic surgery, or tumor resection.
  2. Presence of facial asymmetry.
  3. Patients with cleft lip and/or palate, craniofacial syndromes, or a history of maxillofacial trauma.
  4. Patients in whom the mandibular distal segment requires more than 4° of counterclockwise rotation after BSSO to achieve the final planned position, as the amount of inferior border (basal) resection required would exceed the clinically acceptable limit.

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: Proximal Segment Rotation
Patients underwent mandibular osteotomy followed by repositioning of the proximal segment. Alignment of the inferior border of the proximal segment with the mandibular inferior border was achieved by rotating the proximal segment before fixation.
Procedure: Proximal Segment Rotation
During bimaxillary orthognathic surgery, after bilateral sagittal split osteotomy (BSSO), the proximal mandibular segment is rotated to achieve alignment of the inferior border of the proximal and distal mandibular segments before rigid fixation.
Experimental: Inferior Border Osteotomy Without Proximal Segment Rotation
Patients underwent mandibular osteotomy with the proximal segment maintained in its preoperative position. Alignment of the mandibular inferior border was achieved by performing an additional osteotomy at the inferior border of the proximal segment without rotating the proximal segment before fixation.
Procedure: Inferior Border Osteotomy Without Proximal Segment Rotation
During bimaxillary orthognathic surgery, after bilateral sagittal split osteotomy (BSSO), the proximal mandibular segment is maintained in its preoperative position. Alignment of the mandibular inferior border is achieved by performing an additional osteotomy at the inferior border of the proximal segment without rotating the proximal segment before rigid fixation.

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
Three-dimensional condylar axis angular changes
Time Frame: From enrollment to the end of treatment at 6 months
Changes in condylar axis orientation will be assessed using computed tomography (CT) by measuring the condylar axis angle in the axial, coronal, and sagittal planes relative to standardized reference planes. In the axial plane, the angle between the condylar axis and the midsagittal reference plane (MSR) will be measured. In the coronal and sagittal planes, the angle between the condylar axis and the Frankfort Horizontal Plane (FHP) will be measured. Preoperative, immediate postoperative, and 6-month postoperative measurements will be compared to evaluate postoperative condylar remodeling and positional changes.
From enrollment to the end of treatment at 6 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.
Bezmialem Vakif 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.
January 1, 2026

Primary Completion (Estimated)

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.
December 15, 2026

Study Completion (Estimated)

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.
December 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).
August 6, 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.
August 6, 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 11, 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 11, 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.
August 6, 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.
August 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.
  • E.185561

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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