Comparison of the Clinical and Microbiological Effects of CHX and HOCl Containing Mouthwashes

November 2, 2026 updated by: Mehtap Bilgin Çetin, Baskent University

This study compared two mouthwashes, containing hypochlorous acid (HOCl) or chlorhexidine (CHX), for their effects on dental plaque accumulation, gum bleeding, tooth staining, and bacteria in dental plaque. Participants used each mouthwash during a separate four-day period, with a washout period between treatments. Participants also evaluated their experience with each mouthwash using a questionnaire.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

This single-center, randomized controlled crossover study compared mouthwashes containing 0.02% hypochlorous acid (HOCl) and 0.2% chlorhexidine (CHX) using a four-day plaque regrowth model. Thirty participants were enrolled, and 26 completed both treatment periods.

Each mouthwash was used twice daily, with 10 mL rinsed for one minute, during a four-day period. The treatment periods were separated by a 14-day washout period. Professional prophylaxis was performed at the beginning of each treatment period. Participants refrained from toothbrushing and interdental cleaning during the treatment periods.

Clinical assessments included the Modified Plaque Index, bleeding on probing, and the Modified Stain Index. Supragingival plaque samples were collected at the end of each treatment period for microbiological analysis, including bacterial colony counts and identification by MALDI-TOF mass spectrometry. Participants completed a questionnaire evaluating their experience with each mouthwash and indicated their final preference.

Study Type

Interventional

Enrollment (Actual)

30

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

  • Turkey (Türkiye)
      • Ankara, Turkey (Türkiye), 06000
        • Baskent University Faculty of Dentistry

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

18 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Systemically healthy.
  • Aged 18-65 years.
  • Having at least 22 natural teeth.
  • Nonsmoker.
  • Willing to abstain from alcohol throughout the study.

Exclusion Criteria:

  • Presence of periodontitis or gingivitis.
  • Pregnancy or breastfeeding.
  • Use of medications that may affect periodontal status.
  • Antibiotic or anti-inflammatory medication use within the previous six months.
  • Use of antimicrobial mouth rinses, gels, or chewing gums within the previous three months.
  • Known allergy to any component of the study mouth rinses.
  • Presence of tongue conditions, such as geographic tongue or hairy tongue.
  • Periodontal probing depths of 4 mm or greater.
  • Gingival recession of 2 mm or greater.
  • Use of fixed or removable dental prostheses, including single crowns, or orthodontic appliances.

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: Prevention
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: HOCl followed by CHX

Participants used 0.02% hypochlorous acid mouthwash for four days, followed by a 14-day washout period, and then 0.2% chlorhexidine gluconate mouthwash for four days. Each mouthwash was used twice daily, with 10 mL rinsed for one minute.
Other: Hypochlorous acid 0.02% mouthwash

Rinse with 10 mL for one minute, twice daily for four days.

Other: Chlorhexidine gluconate 0.2% mouthwash

Rinse with 10 mL for one minute, twice daily for four days.
Experimental: CHX followed by HOCl

Participants used 0.2% chlorhexidine gluconate mouthwash for four days, followed by a 14-day washout period, and then 0.02% hypochlorous acid mouthwash for four days. Each mouthwash was used twice daily, with 10 mL rinsed for one minute.
Other: Hypochlorous acid 0.02% mouthwash

Rinse with 10 mL for one minute, twice daily for four days.

Other: Chlorhexidine gluconate 0.2% mouthwash

Rinse with 10 mL for one minute, twice daily for four days.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Modified Plaque Index
Time Frame: At the end of each four-day treatment period.

Dental plaque was assessed using the modified Silness and Löe Plaque Index at six sites per tooth. Each site was scored from 0 (no plaque) to 3 (abundant plaque). Mean scores were calculated for the full mouth and 12 anatomical regions and compared between the HOCl and CHX treatment periods. Mean scores range from 0 to 3; higher scores indicate greater plaque accumulation.
At the end of each four-day treatment period.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Total culturable bacterial count in supragingival plaque
Time Frame: At the end of each four-day treatment period.

Total culturable bacterial counts were measured in supragingival plaque samples collected from molar teeth and expressed as colony-forming units per milliliter (CFU/mL). Counts were compared between the HOCl and CHX treatment periods.
At the end of each four-day treatment period.
Bleeding on Probing (BOP)
Time Frame: At the end of each four-day treatment period.

Bleeding was assessed at six sites per tooth using a periodontal probe. Sites showing bleeding within 30 seconds after probing were recorded as positive. BOP was calculated as the number of bleeding sites divided by the total number of examined sites, multiplied by 100. Full-mouth and regional percentages were calculated. Scores range from 0% to 100%; higher values indicate more gingival bleeding.
At the end of each four-day treatment period.
Modified Stain Index (MSI)
Time Frame: At the end of each four-day treatment period.

Extrinsic tooth staining was assessed in four regions on each buccal and lingual/palatal tooth surface. Intensity was scored from 0 to 3. Area was scored from 1 to 3 only when intensity was 2 or 3, using the region-specific criteria of Macpherson et al. (2000). For intensity scores of 1, the intensity × area value was defined as 1. The participant-level MSI was calculated by averaging these values across examined regions, with a range of 0-9. Higher scores indicate greater staining.
At the end of each four-day treatment period.

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Participant-reported experience with mouthwashes
Time Frame: At the end of each four-day treatment period.

At the end of each treatment period, participants completed a five-item questionnaire assessing mouthwash taste, effects on taste perception, perceived tooth cleanliness, perceived tooth discoloration, and nausea associated with mouthwash use. Each item was rated as 1 (poor), 2 (moderate), or 3 (good). Higher scores indicate a more favorable participant rating. Each item was evaluated separately.
At the end of each four-day treatment period.
Final mouthwash preference
Time Frame: After completion of both four-day treatment periods and the intervening 14-day washout period.

After completing both treatment periods, participants indicated which of the two mouthwashes they preferred. The number of participants preferring each mouthwash was recorded.
After completion of both four-day treatment periods and the intervening 14-day washout period.

Collaborators and Investigators

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

Sponsor

Baskent University

Investigators

  • Principal Investigator: Mehtap Bilgin Cetin, Associate Professor, Baskent University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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)

March 28, 2022

Primary Completion (Actual)

April 19, 2022

Study Completion (Actual)

April 19, 2022

Study Registration Dates

First Submitted

August 29, 2024

First Submitted That Met QC Criteria

September 5, 2024

First Posted (Actual)

September 19, 2024

Study Record Updates

Last Update Posted (Actual)

November 4, 2026

Last Update Submitted That Met QC Criteria

November 2, 2026

Last Verified

November 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • MR1234

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

IPD Plan Description

A decision regarding sharing individual participant data has not yet been made.

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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