EMG-guided Botox Injection Versus Conventional Botox Injection in Gummy Smile Patients

March 19, 2026 updated by: Sherry Fayez Akhnokh, Cairo University

EMG-guided Botox Injection Versus Conventional Injection in Yonsei Point in Gummy Smile Patients: A Randomized Clinical Trial

The goal of this clinical trial is to compare the effect of EMG-guided Botox injection with conventional Botox injection in Yonsei point, in patients with excessive gingival display.

The main question it aims to answer is:

• Does the use of electromyography (EMG) as a guide during Botox injection for patients with gummy smile has better effect than conventional injection in Yonsei point?

Participants will be randomized in equal proportions between intervention and control groups.

  • Preoperative assessment of amount of gingival display, lip length (philtrum and vermilion length), and smile type.
  • For the intervention group, EMG readings will be done in Clinical Neurophysiology Department, Kasr Al-Ainy Hospital EMG-guided Botox injection (Intervention group). Conventional Botox injection in Yonsei point (Control group).

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

32

Phase

  • 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 Backup

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

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Patients with excessive gingival display.
  • Patients with esthetic concerns.
  • Patients with mild to moderate VME (vertical maxillary excess).
  • Normal clinical crown dimensions.
  • Patients aged 18 to 50.
  • Systemically healthy patients.
  • Non-smokers.

Exclusion Criteria:

  • Patients with severe VME (vertical maxillary excess).
  • Pregnant and breastfeeding women.
  • Patients with gingival inflammation and/or enlargement.
  • Inflammation or infection at the site of injection.
  • Patients with known allergy to any of the components of Botox (i.e., saline, human albumin, lactose and sodium succinate).
  • Patients using anticholinesterase or other agents affecting neuromuscular transmission.
  • Psychologically unstable patients or those who have unrealistic expectations and questionable motives.
  • Patients with neuromuscular disorders (e.g., myasthenia gravis, Eaton-Lambert syndrome).

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: EMG-guided Botox injection
Botox injection in patients with gummy smile will be done under electromyography guidance to target the most hyperactive and effective muscle that is the chief factor causing the condition.
Procedure: Botox injection
Botox injection
Other Names:
  • Botulinum toxin injection
Device: EMG
Quantitative Electromyography
Other Names:
  • Electromyography
Drug: Zinc Supplement
To increase efficacy of Botox
Other Names:
  • Zinc supplement in the form of tablets
Active Comparator: Conventional Botox injection in Yonsei point
Conventional injection of Botox is located in Yonsei point, which is the center of a triangle formed by the convergence of Levator labii superioris alaeque nasi (LLSAN), levator labii superioris (LLS), zygomaticus minor (ZMn), muscles, and is located 1 cm lateral to the ala of the nose horizontally and 3 cm above the lip line vertically.
Procedure: Botox injection
Botox injection
Other Names:
  • Botulinum toxin injection
Drug: Zinc Supplement
To increase efficacy of Botox
Other Names:
  • Zinc supplement in the form of tablets

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in amount of gingival display
Time Frame: Baseline, One-week, One-month, three-months, and six-months follow-up
Will be measured using ruler in mm.
Baseline, One-week, One-month, three-months, and six-months follow-up

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Quantitative EMG
Time Frame: Baseline, One-week and six-months follow-up
Will be measured using EMG in mv.
Baseline, One-week and six-months follow-up
Patient satisfaction
Time Frame: Baseline, One-week, One-month, three-months, and six-months follow-up
Will be assessed using questionnaire, on a scale from 1 to 5, where 1 is completely not satisfied and 5 is completely satisfied.
Baseline, One-week, One-month, three-months, and six-months follow-up
Post-operative pain
Time Frame: Baseline, One-week, and One-month follow-up
Will be measured using visual analogue scale (VAS) from 1 to 10.
Baseline, One-week, and One-month follow-up
Smile type
Time Frame: Baseline, One-week, One-month, three-months, and six-months follow-up
Qualitative, by Rubin (1974). Smile is classified into 1. Corner of the mouth (Mona Lisa) smile, 2. Canine Smile, and 3. Full denture smile
Baseline, One-week, One-month, three-months, and six-months follow-up
Change in lip length
Time Frame: Baseline, One-week, One-month, three-months, and six-months follow-up
Will be measured using UNC (University of North Carolina) -15 periodontal probe in mm.
Baseline, One-week, One-month, three-months, and six-months follow-up
Esthetics (Symmetry) for operators
Time Frame: Baseline, One-week, One-month, three-months, and six-months follow-up
Will be measured using 5-point Likert scale, where 1 is significantly asymmetrical and 5 is completely symmetrical.
Baseline, One-week, One-month, three-months, and six-months follow-up

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Cairo University

Investigators

  • Principal Investigator: Sherry Fayez Akhnokh, BSc, Cairo University
  • Study Director: Noha Ghallab, PhD, Cairo University
  • Study Chair: Nesma Shemais, PhD, Cairo 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)

November 1, 2024

Primary Completion (Estimated)

June 1, 2026

Study Completion (Estimated)

August 1, 2026

Study Registration Dates

First Submitted

September 26, 2023

First Submitted That Met QC Criteria

October 3, 2023

First Posted (Actual)

October 10, 2023

Study Record Updates

Last Update Posted (Actual)

March 20, 2026

Last Update Submitted That Met QC Criteria

March 19, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • SFAkhnokh

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.

Clinical Trials on Excessive Gingival Display

Clinical Trials on Botox injection

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Ireland

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

Subscribe