Botulinum Toxin Type A Injection Sites for Oral Commissure Ptosis
July 3, 2026 updated by: Peking University
Injection Site-Based Multicenter Randomized Controlled Trial: Efficacy and Safety of Focal Botulinum Toxin Type A Injection for Oral Commissure Ptosis
This multicenter, prospective, randomized parallel-controlled, assessor-blinded clinical trial aims to address the core clinical pain point of lack of high-level evidence and non-standardized operation in injection site selection for BTX-A treatment of oral commissure ptosis.
A total of 266 eligible subjects will be randomly assigned in a 1:1 ratio to receive either upper DAO or lower DAO BTX-A injection.
The study will compare the clinical efficacy, time-effect characteristics and safety profiles of the two regimens, and conduct stratified analysis of treatment response in different patient subtypes.
The results will determine the optimal injection site for Chinese population, establish standardized operation specifications, fill the international evidence gap, and provide level I evidence for clinical practice.
Study Overview
Status
Not yet recruiting
Conditions
Detailed Description
Oral commissure ptosis is a common aesthetic concern that presents as abnormal downward displacement of the mouth corners at rest, leading to a sad, angry or aged appearance. Botulinum toxin type A (BTX-A) injection is the first-line treatment, but there is no consensus on the optimal injection site in the depressor anguli oris (DAO) muscle.
This multicenter randomized controlled trial will enroll 266 subjects with oral commissure ptosis from 5 top Chinese stomatological hospitals. Subjects will be randomly assigned 1:1 to receive either upper DAO or lower DAO BTX-A injection. The primary endpoint is the improvement of oral commissure ptosis angle at 1 month post-treatment. Secondary endpoints include objective efficacy measures, subjective aesthetic evaluations, and safety profiles during a 6-month follow-up.
This study aims to determine the optimal injection site for Chinese population, establish standardized operation specifications, and provide level I evidence for clinical practice.
Study Type
Interventional
Enrollment (Estimated)
266
Phase
- Phase 4
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
- Name: Xi Gong, D.D.S
- Phone Number: +86 15201304426
- Email: 15201304426@163.com
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
Ages Eligible for Study
- Adult
Accepts Healthy Volunteers
No
Description
Inclusion Criteria:
- Aged 18 to 60 years, any gender
- Meet the diagnostic criteria for oral commissure ptosis: bilateral oral commissure ptosis angle (angle between the oral commissure point and the horizontal line of the ipsilateral vermilion border) > 1° at rest
- Have clear aesthetic demand for oral commissure ptosis improvement and can complete full-cycle follow-up
- No redness, swelling, ulcer, scar, deformity or active infection in the perioral and mental regions
- Have not participated in other interventional clinical trials within 3 months before enrollment
Exclusion Criteria:
- Hypersensitivity to botulinum toxin type A, lidocaine or excipients of injection preparations; or contraindications to botulinum toxin injection (myasthenia gravis, Lambert-Eaton syndrome, motor neuron disease, severe liver and kidney dysfunction, coagulation disorders, uncontrolled autoimmune diseases, malignant tumors)
- History of mid-lower facial botulinum toxin type A injection, soft tissue filling, laser/radiofrequency rejuvenation, perioral surgery or orthognathic treatment within 6 months before enrollment
- Planned perioral treatment within 6 months after enrollment that may affect efficacy evaluation
- Pregnant or lactating women, or those planning to become pregnant within 6 months
- Acquired oral commissure ptosis caused by facial nerve palsy/sequelae, perioral scar traction, severe jaw deformity or severe alveolar bone resorption
- Severe facial asymmetry (difference in bilateral oral commissure ptosis angle > 2°)
- History of botulinum toxin allergy or severe adverse reactions after previous botulinum toxin injection
- Currently using aminoglycoside antibiotics, quinine, calcium channel blockers, anticoagulants or other drugs that may affect botulinum toxin efficacy or increase bleeding risk and cannot discontinue
- History of mental illness, drug/alcohol abuse, or poor compliance unable to complete follow-up
- Other conditions deemed unsuitable for enrollment by the investigator
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 |
Intervention / Treatment |
|---|---|
|
Experimental: Upper Depressor Anguli Oris Injection
Single subcutaneous injection of OnabotulinumtoxinA (Botox®, Allergan, USA) into the upper half of the depressor anguli oris (DAO) muscle.
|
Single subcutaneous injection of onabotulinumtoxinA into the upper half of the depressor anguli oris muscle, total dose 6U bilaterally.
Other Names:
|
|
Active Comparator: Lower Depressor Anguli Oris Injection
Single subcutaneous injection of OnabotulinumtoxinA (Botox®, Allergan, USA) into the lower half of the depressor anguli oris (DAO) muscle.
|
Single subcutaneous injection of onabotulinumtoxinA into the lower half of the depressor anguli oris muscle, total dose 6U bilaterally.
Other Names:
|
What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Improvement of Bilateral Oral Commissure Ptosis Angle from Baseline at 1 Month Post-Treatment
Time Frame: 30±3 days after treatment
|
The primary endpoint is the change in bilateral oral commissure ptosis angle (∠oba) from baseline.
The angle is measured on standardized frontal facial photographs at rest by 3 independent assessors who are completely blinded to group assignment.
The average value of 3 measurements is used as the final result.
|
30±3 days after treatment
|
Secondary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Improvement of Oral Commissure Ptosis Angle at Maximum Smile and Maximum Depression Position
Time Frame: 1, 3, 6 months after treatment
|
Change in oral commissure ptosis angle from baseline measured at maximum smile without teeth exposure and maximum oral commissure depression position on standardized facial photographs.
|
1, 3, 6 months after treatment
|
|
Vertical Elevation Amplitude of the Oral Commissure
Time Frame: 1, 3, 6 months after treatment
|
Change in the vertical distance from the oral commissure point to the ipsilateral pupil from baseline, measured on standardized frontal facial photographs.
|
1, 3, 6 months after treatment
|
|
Merz Facial Aesthetic Scale Score
Time Frame: 1, 3, 6 months after treatment
|
Physician-assessed aesthetic improvement using the full Merz Facial Aesthetic Scale.
Scale range: 0 (No aging) to 4 (Severe aging).
Lower scores indicate better aesthetic outcome.
|
1, 3, 6 months after treatment
|
|
Global Aesthetic Improvement Scale (GAIS)
Time Frame: 1, 3, 6 months after treatment
|
Patient-reported global aesthetic improvement using the full Global Aesthetic Improvement Scale (GAIS).
Scale range: 1 (Much worse) to 5 (Much improved).
Higher scores indicate better aesthetic outcome.
|
1, 3, 6 months after treatment
|
|
Patient Satisfaction Score (FACE-Q)
Time Frame: 1, 3, 6 months after treatment
|
Patient-reported facial appearance satisfaction using the full FACE-Q Facial Appearance Module.
Scale range: 0 (Worst possible appearance) to 100 (Best possible appearance).
Higher scores indicate better outcome.
|
1, 3, 6 months after treatment
|
|
Incidence of Adverse Events (AEs)
Time Frame: From enrollment to 6 months after treatment
|
Incidence, time of onset, clinical manifestation, severity, treatment measures and outcome of all adverse events during the study period.
Severity is graded according to CTCAE 5.0.
|
From enrollment to 6 months after treatment
|
|
Incidence of Toxin Diffusion-Related Adverse Events
Time Frame: From enrollment to 6 months after treatment
|
Incidence of adverse events related to unintended botulinum toxin diffusion, including oral commissure asymmetry, lower lip movement disorder, salivation, dysarthria and abnormal smile.
|
From enrollment to 6 months after treatment
|
|
Incidence of Serious Adverse Events (SAEs)
Time Frame: From enrollment to 6 months after treatment
|
Incidence of serious adverse events that result in death, life-threatening condition, hospitalization, persistent or significant disability, or congenital anomaly/birth defect.
|
From enrollment to 6 months after treatment
|
|
Patient Satisfaction Score (Visual Analog Scale, VAS)
Time Frame: 1, 3, 6 months after treatment
|
Patient satisfaction measured by the 10-point Visual Analog Scale (VAS).
Scale range: 0 (Completely dissatisfied) to 10 (Completely satisfied).
Higher scores indicate higher satisfaction.
|
1, 3, 6 months after treatment
|
Collaborators and Investigators
This is where you will find people and organizations involved with this study.
Sponsor
Investigators
- Principal Investigator: Xi Gong, D.D.S, Peking University School and Hospital of Stomatology
- Principal Investigator: Minjie Chen, D.D.S, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine
- Principal Investigator: Jian Li, D.D.S, Wuhan University School of Stomatology
- Principal Investigator: Yunpeng Li, D.D.S, School of Stomatology, Air Force Medical University
- Principal Investigator: Sien Zhang, D.D.S, Guanghua School of Stomatology, Sun Yat-sen 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 (Estimated)
July 1, 2026
Primary Completion (Estimated)
June 1, 2027
Study Completion (Estimated)
December 1, 2027
Study Registration Dates
First Submitted
June 5, 2026
First Submitted That Met QC Criteria
June 11, 2026
First Posted (Actual)
June 15, 2026
Study Record Updates
Last Update Posted (Actual)
July 7, 2026
Last Update Submitted That Met QC Criteria
July 3, 2026
Last Verified
June 1, 2026
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
Other Study ID Numbers
- PekingUDAO
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
product manufactured in and exported from the U.S.
No
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