Orthognathic Surgery in Anterior Open Bite: a Retrospective Study of 50 Patients With Initial Tongue Malposition (COBA 50)

April 2, 2026 updated by: Hospices Civils de Lyon

The anterior gap is defined by a lack of contact between the upper and lower dental arches.

It is mainly due to the persistence of infantile swallowing during and after childhood, i.e. interposition of the tongue between the two dental arches.

Patients presenting with an anterior gap in adulthood are likely to develop functional sequelae (masticatory difficulties, dental loosening, periodontal disease, etc.) and aesthetic sequelae (edentulous smile, excess height of the lower third of the face compared to the upper and middle third).

Patients who are diagnosed with this condition very often benefit from orthodontic-surgical treatment, comprising a period of orthodontics followed by orthognathic surgery to close the anterior gap. This is combined with lingual re-education to treat infantile swallowing. This lingual re-education is not always carried out, either because infantile swallowing has not been diagnosed, or because of a lack of cooperation on the part of the patient, or because of difficulties in finding a suitable specialist. When rehabilitation is introduced, it is sometimes only after surgery, and for a short time.

For example, it has been observed that among all patients undergoing orthognathic surgery, those with an anterior gap were particularly at risk of surgical treatment failure, or recurrence in the short to medium term.

The main reason cited was the persistence of infantile swallowing and consequent malpositioning of the tongue between the dental arches, creating permanent pressure on the lingual surface of the teeth and eventually leading to recurrence of the gap.

Identifying patient management factors associated with postoperative recurrence of anterior hollowness in patients with infantile swallowing would enable us to adapt the management of these patients.

Study Overview

Status

Status

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

Conditions

Conditions

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Intervention / Treatment

Intervention / Treatment

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Study Type

Study Type

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Observational

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.
50

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

  • France
    • France
      • Lyon, France, France, 69004
        • Service de chirurgie en maxillo-faciale Hôpital de la Croix Rousse -Lyon

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

No

Sampling Method

Non-Probability Sample

Study Population

patients undergoing orthognathic surgery with a gap prior to surgery (50 patients)

Description

Inclusion Criteria:

  • Major patients
  • Having undergone ortho gnathic surgery in the Maxillofacial Surgery Department of the Croix Rousse Hospital
  • Patients with an anterior gap of more than 3 mm
  • Abnormal tongue position at diagnosis

Exclusion Criteria:

  • Syndromic patients (cleft lip and palate, craniostenosis)
  • Patient refusal

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

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
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.
Relapse of anterior open bite
All patients who presented relapse of anterior open bite after 6 months post operative.
Other: type of post-operative rehabilitation : with physiotherapy or speech therapy

mean duration of rehabilitation

  • assess the tongue position at rest, and during speech
  • assess the surgical movements associated with relapse : advancement, rotation, expansion, genioplasty
No relapse of anterior open bite
All patients who did not present a relapse of anterior open bite after 6 months post operative.
Other: type of post-operative rehabilitation : with physiotherapy or speech therapy

mean duration of rehabilitation

  • assess the tongue position at rest, and during speech
  • assess the surgical movements associated with relapse : advancement, rotation, expansion, genioplasty

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
Measurement of the association between anterior open bite recurrence, defined as the absence of contact between the upper and lower incisors at 6 months postoperatively, and the rehabilitation factors.
Time Frame: 6 months
Duration of rehabilitation in months
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.
Hospices Civils de Lyon

Study record dates

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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, 2022

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 1, 2025

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.
August 1, 2025

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 28, 2025

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.
April 2, 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.
April 9, 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.
April 9, 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.
April 2, 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.
April 1, 2026

More Information

Terms related to this study

Keywords

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.
  • 25-5191

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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