1. Randomization Method
In this study, balanced permuted block randomization with a block size of six is used to allocate participants into intervention and control groups.
2. Unit of Randomization
The unit of randomization is individual.
3. Stratification
No stratification is applied in the randomization process.
4. Randomization Tools
Sequence Generation Instrument: Statistical software is utilized to generate the block random sequence.
Allocation Concealment Instrument: Sequentially Numbered, Opaque, Sealed Envelopes (SNOSE), impermeable to light, are utilized.
5. Random Sequence Generation
The random sequence is generated prior to the start of sampling by an independent researcher/statistician who has no role in clinical examinations, data collection, or patient treatment.
Given the total sample size of 60 participants and a block size of six, 10 blocks of six are calibrated.
Within each 6-element block, three codes for the intervention group (A) and three codes for the control group (B) are randomly arranged in various combinations to maintain a 1:1 allocation ratio throughout the study.
6. Allocation Concealment and Blinding
To implement allocation concealment and prevent bias among the investigator and participants regarding the upcoming group allocation:
Allocation codes generated by the independent researcher are placed inside sealed, light-impermeable, opaque envelopes marked sequentially with serial numbers from 1 to 60.
The envelopes remain strictly sealed until participant enrollment.
Only after comprehensive participant evaluation, verification of inclusion and exclusion criteria, and obtaining written informed consent, the envelope corresponding to the entry sequence is opened to assign the specific mouthwash.
Due to the double-blind nature of the study, the mouthwash containers are made identical in appearance, volume, color, and packaging, labeled solely with codes A and B. Consequently, outcome assessors (clinical index examiners), and the data analyst remain blinded to the assigned interventions until the completion of data analysis.
To achieve effective blinding, an independent individual outside the research team packages both mouthwashes (0.2% Chlorhexidine and the Aloe Vera-Tea Tree combination) in identical, unlabelled bottles that carry only randomized identification codes. An independent researcher generates the random sequence and places allocation details in sealed opaque envelopes.
The breakdown of blinding for all involved parties is as follows:
1. Principal Investigator and Healthcare Personnel (Dentists and Clinical staff):
The principal investigator and the clinical personnel responsible for patient care—including baseline scaling, root planing, and oral hygiene instruction—are kept unaware of the treatment group assignments. Because an independent third party handles the distribution of the coded bottles, the clinical staff cannot influence patient management based on treatment status.
2. Data Collectors and Outcome Assessors:
The clinical evaluator who measures outcome variables—specifically the Gingival Index (GI), Plaque Index (PI), Sulcus Bleeding Index (SBI), and Lobene Stain Index—is completely blinded to patient group allocation. Examinations and data entry proceed strictly without any knowledge of the mouthwash type used by the participant.
3. Data Analyst and Manuscript Drafters:
The biostatistician receives and analyzes the dataset using anonymized group codes (e.g., Group A and Group B). Similarly, the authors drafting the manuscript remain blinded to the true identity of the study groups until all statistical analyses are finalized and the dataset is unblinded.
4. Data Safety and Monitoring Board (DSMB):
If the safety monitoring committee reviews any adverse events or interim data, the information is provided strictly in a coded format to ensure an unbiased safety evaluation.