Effect of Benzydamine Hydrochloride Mouthrinse on Plaque Accumulation in Periodontally Healthy Female Subjects (BHCl-PLAQUE)

Effect of Benzydamine Hydrochloride During Short-term Restricted Oral Hygiene: a Randomized, Placebo-controlled Trial

The goal of this clinical trial is to evaluate the effect of a mouthrinse containing an active ingredient benzydamine hydrochloride in the absence of daily oral hygiene. The study includes periodontally healthy female subjects and experimental phase will last for three days. Plaque accumulation is the primary evaluated outcome, measured by a particular periodontal index called Plaque Control Record (PCR). Gingival inflammation (bleeding) is the secondary evaluated outcome, measured by a particular periodontal index called Bleeding on Probing (BoP). Researchers will compare benzyadamine hydrochloride mouthrinse to a placebo (a look-alike substance that contains no active ingredient) mouthwash to see whether benzydamine hydrochloride use results in greater plaque accumulation.

Study Overview

• Status: Completed
• Conditions: Oral Health; Plaque Induced Gingival Disease
• Intervention / Treatment: Drug: Benzydamine hydrochloride mouthrinse; Other: Placebo mouthrinse

Detailed Description

This study is designed as a randomized, double-blind, placebo-controlled, parallel-group clinical trial to evaluate the effects of a benzydamine hydrochloride-containing mouthrinse on supragingival plaque accumulation and gingival inflammatory response under conditions of restricted mechanical oral hygiene. The experimental model is based on a short-term plaque regrowth protocol, enabling controlled assessment of the chemical effects of the investigational product in the absence of confounding mechanical plaque removal.

A total of 50 periodontally healthy female participants will be enrolled and randomly assigned to either the test group (benzydamine hydrochloride mouthrinse) or the control group (placebo mouthrinse). Randomization will be performed using a predefined allocation sequence to ensure balanced group distribution. Both participants and investigators will be blinded to group assignment, with the test and placebo formulations matched in color, taste, and packaging to maintain allocation concealment.

Prior to the experimental phase, all participants will receive professional dental prophylaxis to establish a standardized baseline with minimal plaque accumulation and absence of gingival inflammation. Following this, subjects will be instructed to refrain from all mechanical oral hygiene procedures, including toothbrushing and interdental cleaning, for the duration of the 3-day experimental period.

During the experimental phase, participants will use the assigned mouthrinse twice daily, rinsing with 15 mL of solution for a standardized duration according to detailed written instructions.

The investigational product contains benzydamine hydrochloride, a locally acting non-steroidal anti-inflammatory agent with analgesic and anti-inflammatory properties, which may influence gingival tissue response and potentially affect plaque accumulation dynamics. The placebo formulation is devoid of active pharmacological ingredients but is otherwise identical in formulation characteristics to ensure effective blinding.

Clinical assessments will be conducted at baseline and at the end of the 3-day experimental period. Plaque accumulation will be assessed using the Plaque Control Record (PCR), which quantifies the presence of plaque on six tooth surfaces and expresses the findings as a percentage of plaque-positive sites. Gingival inflammation will be evaluated as a secondary outcome using Bleeding on Probing (BoP), recorded dichotomously following periodontal probing.

All clinical measurements will be performed by a previously calibrated examiner using standardized instruments and probing force to ensure consistency and reproducibility of recorded data.

This study design allows for the isolation of the chemical effects of benzydamine hydrochloride by eliminating mechanical plaque control, thereby providing insight into its influence on early plaque formation and gingival inflammatory response compared to placebo. The short duration of the experimental phase ensures participant safety while allowing detection of early biological changes in plaque accumulation and gingival health.

• Study Type: Interventional
• Enrollment (Actual): 50
• Phase: Phase 4

Contacts and Locations

Study Locations

• Croatia
  • Zagreb, Croatia, 10000
    • School of Dental Medicine, University of Zagreb

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• dentate subjects with at least 24 healthy teeth
• no history of periodontal disease, confirmed by a clinically healthy periodontium, defined as probing pocket depth (PPD) ≤ 3 mm and no interdental clinical attachment loss

Exclusion Criteria:

• pregnant or lactating females
• using hormonal contraceptives
• reporting systemic diseases or pharmacological treatment that could affect gingival inflammation
• use of antibiotics within 6 months before the study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Benzydamine Hydrochloride mouthrinse; Experimental arm participants will use the assigned mouthrinse containing benzydamine hydrochloride twice daily, rinsing with 15 mL of solution for a standardized duration according to the manufacturer's instructions.	Drug: Benzydamine hydrochloride mouthrinse; Participants assigned to the intervention arm will use a mouthrinse containing benzydamine hydrochloride twice daily. A volume of 15 mL will be used per rinse, following a standardized rinsing duration in accordance with the manufacturer's instructions. During the 3-day experimental period, participants will refrain from all mechanical oral hygiene measures to allow assessment of the chemical effects of the mouthrinse on plaque accumulation and gingival inflammation.
Placebo Comparator: Placebo mouthrinse; Placebo mouthwash arm participants will use the assigned placebo mouthrinse, formulated to be identical in color, taste, and packaging to ensure effective allocation concealment. The mouthrinse will be used twice daily, with 15 mL of solution, following a standardized rinsing duration in accordance with the manufacturer's instructions.	Other: Placebo mouthrinse; Participants assigned to the placebo arm will use a mouthrinse without active pharmacological ingredients, formulated to match the test product in color, taste, and packaging to ensure blinding. The mouthrinse will be used twice daily in a volume of 15 mL, following a standardized rinsing duration in accordance with the manufacturer's instructions. Mechanical oral hygiene measures will be suspended throughout the 3-day experimental period.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
3-day plaque accumulation assessed by Plaque Control Record (PCR)	Plaque accumulation will be evaluated using the Plaque Control Record (PCR), which assesses the presence or absence of supragingival plaque on six surfaces of each tooth. The results will be expressed as the percentage of plaque-positive surfaces relative to the total number of examined surfaces, providing a quantitative measure of plaque regrowth under conditions of suspended mechanical oral hygiene.	Baseline (Day 0) and Day 3

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
3-day gingival inflammation assessed by Bleeding on Probing (BoP)	Gingival inflammation will be assessed using Bleeding on Probing (BoP), recorded dichotomously (presence/absence of bleeding) following gentle probing of the gingival sulcus at standardized sites. The outcome will be expressed as the percentage of bleeding-positive sites, reflecting the degree of gingival inflammatory response.	Baseline (Day 0) and Day 3

Collaborators and Investigators

• Sponsor: University of Zagreb

Study record dates

Study Major Dates

• Study Start (Actual): February 1, 2013
• Primary Completion (Actual): May 1, 2013
• Study Completion (Actual): May 1, 2013

Study Registration Dates

• First Submitted: April 27, 2026
• First Submitted That Met QC Criteria: April 27, 2026
• First Posted (Actual): May 4, 2026

Study Record Updates

• Last Update Posted (Actual): May 4, 2026
• Last Update Submitted That Met QC Criteria: April 27, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Randomized Controlled Trial; Oral hygiene; Dental plaque; Anti-inflammatory Agent; Benzydamine Hydrochloride
• Additional Relevant MeSH Terms: Stomatognathic Diseases; Tooth Diseases; Dental Deposits; Dental Plaque
• Other Study ID Numbers: 05-PA-26-22/13

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No