Licorice Extract Gel Versus Diode Laser for Physiologic Gingival Pigmentation

January 13, 2026 updated by: Rania Mostafa Eissa, Alexandria University

A Comparative Evaluation of the Effectiveness of Topical Licorice Extract Gel and Diode Laser 445 nm on Physiologic Gingival Pigmentation

This randomized controlled clinical trial aims to compare the effectiveness of topical licorice extract gel and diode laser (445 nm) in the treatment of physiologic gingival pigmentation.

Twenty-four adult patients presenting with physiologic melanin pigmentation in the anterior esthetic zone of the maxillary or mandibular gingiva will be randomly allocated into two equal groups. One group will be treated with diode laser therapy, while the other group will receive topical licorice extract gel.

Clinical outcomes will be assessed using standardized gingival pigmentation indices and patient satisfaction questionnaires over a follow-up period of 36 weeks.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

This randomized controlled clinical trial will be conducted at the outpatient clinic of the Department of Oral Medicine, Periodontology, Oral Diagnosis and Oral Radiology, Faculty of Dentistry, Alexandria University, Egypt.

Eligible participants aged 18-50 years with physiologic gingival pigmentation will be randomly assigned into two groups. Group A will receive gingival depigmentation using a 445 nm diode laser, while Group B will receive topical licorice extract gel applied three times daily.

The intensity and distribution of gingival pigmentation will be evaluated using the Dummett-Gupta Oral Pigmentation Index (DOPI) and Gingival Pigmentation Index (GPI). Patient satisfaction will also be assessed. Clinical evaluations will be performed at baseline, 1 week, 4 weeks, 12 weeks and 36 weeks after treatment.

Study Type

Interventional

Enrollment (Actual)

26

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 Locations

  • Egypt
    • Alexandria Governorate
      • Alexandria, Alexandria Governorate, Egypt, 21526
        • Oral Medicine and Diagnosis Clinic, Faculty of Dentistry, Alexandria 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

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Adults (18 to 50 years old) of either sex with physiologic melanin pigmentation in the anterior esthetic zone of the maxillary or mandibular gingiva.
  • Systemically healthy individuals

Exclusion Criteria:

  • Smokers
  • Pregnant or lactating females
  • Patients taking drugs associated with gingival pigmentation
  • Patients with periodontal disease
  • History of gingival depigmentation
  • Known hypersensitivity to licorice extract
  • Poor oral hygiene
  • Presence of systemic diseases

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
Active Comparator: Diode Laser Group
Participants receive gingival depigmentation using a 445 nm diode laser.
Device: Diode Laser 445 nm
Gingival depigmentation performed using a diode laser with a wavelength of 445 nm in continuous wave mode at 1 W power.
Experimental: Licorice Extract Gel Group
Participants apply topical licorice extract gel to pigmented gingival areas three times daily.
Drug: Licorice Extract Gel
Topical licorice extract gel applied to pigmented gingival areas three times daily for one month, with continuation for a second and third month if required.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in gingival pigmentation intensity
Time Frame: Baseline, 1 week, 4 weeks, 12 weeks and 36 weeks
Degree of gingival pigmentation assessed using the Dummett-Gupta Oral Pigmentation Index (DOPI; scores range from 0 to 3), with higher scores indicating increased pigmentation intensity.
Baseline, 1 week, 4 weeks, 12 weeks and 36 weeks
Change in gingival pigmentation distribution
Time Frame: Baseline, 1 week, 4 weeks, 12 weeks and 36 weeks
Gingival pigmentation distribution was assessed using the Gingival Pigmentation Index (GPI). The GPI is an ordinal scale ranging from 0 to 3, where 0 indicates absence of pigmentation and 3 indicates widespread gingival pigmentation. Higher scores represent greater extent of gingival pigment distribution (worse pigmentation).
Baseline, 1 week, 4 weeks, 12 weeks and 36 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Participant Satisfaction
Time Frame: 3 months post-treatment
Participant satisfaction was assessed using a study-specific questionnaire consisting of four questions evaluating perceived esthetic improvement, fulfillment of expectations, self-confidence related to smile appearance, and willingness to recommend the treatment. Responses were recorded as categorical (non-numerical) variables, and no numerical scale was calculated. Outcomes were analyzed descriptively, with more favorable responses indicating higher satisfaction.
3 months post-treatment
Postoperative pain intensity (laser group only)
Time Frame: Immediately post-procedure, Day 1 and Day 7 postoperatively
Postoperative pain intensity was assessed in the diode laser group only using the Visual Analog Scale (VAS; range 0-10), where 0 indicates no pain and 10 indicates the worst imaginable pain. This outcome was not applicable to the licorice extract gel group due to the non-invasive nature of the intervention.
Immediately post-procedure, Day 1 and Day 7 postoperatively

Collaborators and Investigators

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

Sponsor

Alexandria 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)

April 1, 2025

Primary Completion (Actual)

January 1, 2026

Study Completion (Actual)

January 1, 2026

Study Registration Dates

First Submitted

December 24, 2025

First Submitted That Met QC Criteria

December 24, 2025

First Posted (Estimated)

January 8, 2026

Study Record Updates

Last Update Posted (Actual)

January 15, 2026

Last Update Submitted That Met QC Criteria

January 13, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • RaniaEissa-Dent-1999

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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