Reducing Gingival Pigmentation Through Workplace Mitigation in Restaurant Oven Workers

NCT07805824 | Completed Phase 4

• 1 other identifier: UOKU-OGMI-2026-001
• Study Type: interventional
• Target: 200
• Locations: 1 country
• Sites: 1

Brief Summary

Restaurant workers who spend much of their workday near ovens, grills, or other cooking equipment may breathe smoke and experience high heat. This study will test whether a workplace safety package can lower these exposures and reduce changes in the natural coloring of the gums. Twenty restaurants and about 200 adult workers will take part. Restaurants, rather than individual workers, will be assigned by chance to receive the safety package immediately or after the 24-week comparison period. The package may include improving exhaust hoods and ventilation, maintaining cooking equipment, shielding hot surfaces, scheduled work, rest and hydration, task rotation, worker education, and respiratory protection during high-exposure tasks. Researchers will assess workers at the beginning of the study and again at 12 and 24 weeks. They will measure gum color using standardized photographs, air pollution, carbon monoxide, heat, gum health, and work-related symptoms. Researchers will also study selected saliva, urine, and mouth-cell markers related to inflammation, oxidative stress, and pigment pathways. The study will determine whether reducing workplace heat and air pollution is associated with less change in gum coloring and related biological changes.

Conditions

Gingival Pigmentation; Occupational Heat Exposure; Occupational Air Pollution Exposure

Outcome Measures

Primary Outcomes (1)

• Change From Baseline in Objective Gingival Melanin Index at Week 24

  Between-group difference in change from baseline to week 24 in the Objective Gingival Melanin Index (OGMI). The OGMI is a continuous composite score derived from calibrated cross-polarized intraoral photographs using CIELAB L\*, a\*, and b\* color parameters from standardized regions of interest on the attached gingiva of the maxillary anterior sextant.

  Baseline to Week 24

Secondary Outcomes (1)

• Change From Baseline in Personal PM2.5 Exposure at Week 24

  Exposure at Week 24

Study Arms (2)

Immediate Workplace Mitigation

EXPERIMENTAL

Restaurants assigned to this arm receive a comprehensive workplace heat and air-pollution mitigation package immediately after randomization. The package includes improved local exhaust ventilation and source capture, cooking-equipment maintenance, heat shielding or insulation, work-rest-hydration schedules, task rotation, worker education, and task-appropriate respiratory protection during high-exposure activities. The package is implemented within six weeks after randomization and monitored throughout the 24-week follow-up period.

Other: Workplace Heat and Air Pollution Mitigation Package

Delayed Workplace Mitigation

ACTIVE COMPARATOR

IRestaurants assigned to this arm continue their usual workplace practices during the 24-week primary comparison period and do not receive the mitigation package during that period. After the 24-week primary endpoint, they receive the identical workplace heat and air-pollution mitigation package, including ventilation improvements, equipment maintenance, heat shielding or insulation, work-rest-hydration schedules, task rotation, worker education, and task-appropriate respiratory protection.

Other: Delayed Workplace Heat and Air Pollution Mitigation Package

Interventions

Delayed Workplace Heat and Air Pollution Mitigation Package OTHER

Restaurants assigned to this arm will not receive the mitigation package during the 24-week primary comparison period. They will receive the identical workplace heat and air-pollution mitigation package after the 24-week primary endpoint. The package includes engineering controls, administrative controls, worker education, and task-appropriate respiratory protection as described for the immediate-mitigation arm.

Delayed Workplace Mitigation

Workplace Heat and Air Pollution Mitigation Package OTHER

Restaurants assigned to this arm will receive a workplace heat and air-pollution mitigation package. Engineering controls include optimization of local exhaust ventilation, installation of additional source-capture hoods where feasible, maintenance of cooking equipment to reduce incomplete combustion, and shielding or insulation of radiant heat sources. Administrative controls include work-rest-hydration schedules based on wet bulb globe temperature monitoring, task rotation, and worker education on exposure recognition and symptom reporting. Task-appropriate respiratory protection, with a minimum N95 filtering facepiece, will be used during high-exposure tasks such as charcoal ignition, deep frying, and oven cleaning. Implementation will be completed within six weeks after randomization. Ventilation performance, work-rest procedures, and area PM2.5 will be monitored during follow-up.

Immediate Workplace Mitigation

Eligibility Criteria

• Age: 18 Years - 60 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Adults aged 18-60 years.
• Employment in an eligible restaurant for at least six months.
• At least 20 work hours per week.
• At least 10 work hours per week within approximately five meters of active cooking or combustion equipment.
• Expected continued employment for the 24-week follow-up period.
• Ability to provide written informed consent.
• Restaurant-level eligibility requires use of ovens, grills, fryers, charcoal, wood, gas, or comparable high-temperature equipment; at least six potentially eligible workers; permission for exposure monitoring and engineering assessment; and no scheduled closure or major renovation during follow-up.

You may not qualify if:

• Recent gingival depigmentation.
• Active oral pigmented lesion requiring diagnostic referral.
• Severe untreated periodontitis or acute oral infection.
• Medication known to alter pigmentation, including antimalarials, minocycline, or chemotherapeutic agents.
• Systemic disease judged likely to cause pathological pigmentation.
• Current chemotherapy.
• Inability to undergo standardized photography.
• Pregnancy if venipuncture or heat-strain procedures create additional risk.
• Inability to provide informed consent.
• Restaurants with an imminent mandatory ventilation replacement that would compromise the comparator condition.

Sponsors & Collaborators

• Salah M. Ibrahim: lead

Study Sites (1)

the University of Kufa

Najaf, Najaf, 5300, Iraq

Location

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: Clinical photographers, image graders, laboratory personnel, outcome adjudicators, and the primary statistician are masked to allocation.
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Assistant Professor, Department of Oral Surgery, College of Dentistry, University of Kufa

Study Record Dates

• First Submitted: September 1, 2026
• First Posted: September 4, 2026
• Study Start: January 1, 2026
• Primary Completion: January 1, 2026
• Study Completion: June 30, 2026
• Last Updated: September 4, 2026

Record last verified: 2026-08

Locations

IR (1)