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NCT Number: NCT07325825

Licorice Extract Gel Versus Diode Laser for 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.

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Key information

Conditions

Gingival Hyperpigmentation

Age range

18 year–50 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Oral Medicine and Diagnosis Clinic, Faculty of Dentistry, Alexandria University

Alexandria, Alexandria Governorate, 21526, Egypt

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Diode Laser 445 nm

Device

Gingival depigmentation performed using a diode laser with a wavelength of 445 nm in continuous wave mode at 1 W power.

Licorice Extract Gel

Drug

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.

Primary outcomes

  1. 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.

  2. 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).

Secondary outcomes

  1. 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.

  2. 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.

Sponsors and collaborators

Lead sponsor

Alexandria University

Other

Registry information

Official study title

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

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Jan 8, 2026
Registry last updated
Jan 15, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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