Botulinum Toxin Type A Versus Cross-Linked Hyaluronic Acid Filler Myomodulation for Non-Surgical Management of Excessive Gingival Display

July 17, 2026 updated by: Nada Mahmoud Al-Aboud, Al-Azhar University

A Prospective Randomized Controlled Clinical Trial Evaluating the Efficiency and Patient Satisfaction of Botulinum Toxin Type A Versus Cross-Linked Hyaluronic Acid Filler in the Management of Excessive Gingival Display

This randomized controlled trial compared the clinical efficacy and patient satisfaction of two non-surgical treatments for excessive gingival display (gummy smile): botulinum toxin type A (BTX-A) and cross-linked hyaluronic acid (HA) filler myomodulation. Excessive gingival display is defined as exposure of 3 mm or more of gingival tissue during maximal smiling. It affects approximately 14% of women and 7% of men and is associated with reduced self-confidence, smile suppression in social settings, and impaired quality of life. When caused by hyperactivity of the upper lip elevator muscles, it can be treated without surgery using injectable therapies. Twenty patients (18 females, 2 males; age 18-45 years) with excessive gingival display greater than 3 mm were randomly allocated 1:1 to one of two groups. Group A (n=10) received bilateral injections of botulinum toxin type A (Refinex; 5 IU per side) at the Yonsei point. Group B (n=10) received cross-linked hyaluronic acid filler (Juvederm Voluma with lidocaine; 1.0 mL total) injected at six periosteal sites around the nose and upper lip using a myomodulation technique. Participants were assessed at baseline and at 1, 3, and 6 months after treatment. The primary outcome was maximum gingival display measured in millimeters using a calibrated periodontal probe. Secondary outcomes included patient satisfaction measured by Visual Analog Scale and a 12-item questionnaire, and adverse event monitoring. Both treatments produced equivalent gingival display reductions at one month (BTX-A: 69.6%; HA: 63.0%). At six months, the HA group maintained a statistically significant 26.4% improvement while the BTX-A group showed near-complete relapse. Despite this, BTX-A patients reported higher categorical satisfaction. Both treatments had excellent safety profiles.

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

Study Design: Prospective, two-arm, parallel-group randomized controlled clinical trial. Setting: Oral Diagnosis Clinic, Faculty of Dentistry, Al-Azhar University, Cairo, Egypt. Ethics: Approved by the Research Ethics Committee, Faculty of Dental Medicine for Girls, Al-Azhar University (Code: P-ME-25-02). All participants provided written informed consent. Study conducted in accordance with the Declaration of Helsinki. Randomization: Performed using the National Cancer Institute Clinical Trial Randomization Tool (https://ctrandomization.cancer.gov/), Maximal procedure, Maximum Tolerated Imbalance = 3, allocation ratio 1:1. Group A - BTX-A: Refinex (botulinum toxin type A), 5 IU per side, bilateral injection at the Yonsei point (convergence of levator labii superioris alaeque nasi, levator labii superioris, and zygomaticus minor muscles), single session, 30-gauge needle. Group B - HA Myomodulation: Juvederm Voluma with lidocaine (20 mg/mL cross-linked hyaluronic acid, VYCROSS technology), total 1.0 mL per patient, six periosteal deposits of 0.2 mL each at the piriform fossa bilaterally, anterior nasal spine, and nasal base bilaterally, 27-gauge needle. Negative aspiration confirmed before each injection. Outcome Measurement: Maximum gingival display measured by UNC-15 periodontal probe (three consecutive measurements averaged) at baseline (T0), 1 month (T1), 3 months (T2), and 6 months (T3). Patient satisfaction by Visual Analog Scale (0-10 cm) for overall smile and gingival display satisfaction. Psychosocial impact by 12-item Likert questionnaire. Adverse event monitoring at all follow-up visits. Standardized digital photography at each time point (Nikon D5600, 105mm macro lens). Statistics: SPSS v26.0. Independent-samples t-test for between-group comparisons. Paired-samples t-test for within-group comparisons. Chi-square and Fisher exact tests for categorical data. Pearson correlation for associations between gingival display reduction and satisfaction. Significance at p less than 0.05.

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.
20

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

  • Egypt
    • Cairo Governorate
      • Cairo, Cairo Governorate, Egypt
        • Faculty of Dental Medicine for Girls, Al-Azhar University

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:

  1. Excessive gingival display >3 mm during maximal smiling (measured by UNC-15 periodontal probe)
  2. Age 18-45 years
  3. Either sex
  4. Ability to provide written informed consent
  5. Availability for all follow-up visits at 1, 3, and 6 months post-treatment

Exclusion Criteria:

  1. Chronic neurological diseases or blood coagulation disorders
  2. Pregnancy or lactation
  3. Immunological disease or current immunosuppressive drug therapy
  4. Known sensitivity or allergy to botulinum toxin or hyaluronic acid products
  5. Previous treatment for gummy smile within 12 months
  6. Extreme age (outside 18-45 range) or pediatric patients

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: None (Open Label)

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: BTX-A Group
Participants received bilateral injections of botulinum toxin type A (Refinex®; 5 IU per side) at the Yonsei point - the anatomical convergence of the levator labii superioris alaeque nasi (LLSAN), levator labii superioris (LLS), and zygomaticus minor muscles - using an insulin syringe with a 30-gauge needle. Total dose: 10 IU.
Drug: Botulinum Toxin Type A (Refinex®)
5 International Units per side, bilateral injection at Yonsei point, single-session treatment
Active Comparator: HA Myomodulation Group
Participants received cross-linked hyaluronic acid filler (Juvéderm Voluma® with lidocaine; 20 mg/mL; VYCROSS technology) administered as five periosteal deposits of 0.2 mL each (total 1.0 mL) at: piriform fossa and anterior nasal spine bilaterally, and base of nose, using a 27-gauge needle. Negative aspiration confirmed before each injection.
Drug: Cross-Linked Hyaluronic Acid Filler (Juvéderm Voluma® with Lidocaine)
20 mg/mL cross-linked HA, total 1.0 mL per patient, five periosteal injection sites; VYCROSS technology

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
Maximum Gingival Display
Time Frame: Baseline (T0), 1 month (T1), 3 months (T2), 6 months (T3) post-treatment
Maximum gingival display (mm) measured from the lower border of the upper lip to the free gingival margin at the right central incisor during standardised maximal smiling, using a UNC-15 periodontal probe. Three consecutive measurements taken and averaged by the same operator.
Baseline (T0), 1 month (T1), 3 months (T2), 6 months (T3) post-treatment

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
Overall Smile Satisfaction
Time Frame: Baseline (T0) and 6 months (T3) post-treatment
Patient-reported overall smile satisfaction on a 100-mm Visual Analog Scale (0=completely dissatisfied, 10=completely satisfied)
Baseline (T0) and 6 months (T3) post-treatment
Gingival Display Satisfaction
Time Frame: Baseline (T0) and 6 months (T3) post-treatment
Patient-reported gingival display satisfaction scored on a 100-mm Visual Analog Scale (0 = completely dissatisfied, 10 = completely satisfied)
Baseline (T0) and 6 months (T3) post-treatment
Psychosocial Impact and Treatment Satisfaction
Time Frame: Baseline (T0) and 6 months (T3) post-treatment
12-item Likert-scale questionnaire assessing aesthetic self-perception, social smiling behaviour, and treatment endorsement including willingness to repeat and recommend the procedure
Baseline (T0) and 6 months (T3) post-treatment
Adverse Events
Time Frame: 1 month (T1), 3 months (T2), and 6 months (T3) post-treatment
Monitoring for injection-site reactions, lip asymmetry, bruising, swelling, or other treatment-related adverse events at all follow-up visits
1 month (T1), 3 months (T2), and 6 months (T3) post-treatment

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.
Al-Azhar 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, 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.
February 28, 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 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 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 21, 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 17, 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.
  • P-ME-25-02

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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