A Multicentre Randomised Controlled Trial Evaluating the Efficacy of the SMILE™ Module for Improving Short-term Periodontal Outcomes, Compliance, and Acceptability Among Clinical Dental Students

The participants will be recruited from four Malaysian universities and two Indonesian universities. Individuals who meet the eligibility criteria and provide written informed consent will undergo screening, oral examination, professional oral prophylaxis and any necessary dental treatment to establish a comparable baseline oral condition prior to randomisation.

Participants will then be randomly assigned in a 1:1 ratio to either the SMILE intervention group or the conventional toothbrushing control group using a computer-generated stratified randomisation sequence. Allocation concealment will be maintained through a centralised electronic allocation system. Outcome assessors and data analysts will remain blinded to group allocation.

The SMILE intervention group will receive a structured behavioural module delivered through the SMILE mobile application. The programme includes standardised instruction on siwak preparation, brushing technique, storage, recommended frequency of use, instructional videos, supervised hands-on practice, a standardised siwak kit, and daily monitoring using the mobile application with a paper logbook available as a contingency.

Participants in the control group will receive a structured conventional toothbrushing module following the same training schedule and monitoring procedures. A standardised toothbrush kit and the study application containing toothbrushing educational materials will be provided to ensure equivalent participant support and follow-up throughout the study.

Following completion of training, participants will perform their allocated oral hygiene practice for 21 consecutive days. Adherence to the assigned intervention will be monitored using the study application or the paper logbook when required. Clinical assessments will be conducted at baseline and at Day 21 by calibrated examiners using standardised periodontal examination procedures. The study is designed to determine the efficacy of the SMILE module under controlled conditions using conventional toothbrushing as the active control intervention.

Inclusion criteria

• Adults aged 18 - 24 years
• Clinical dental students enrolled at one of the participating universities.
• Participants with a maximum diagnosed with plaque-induced gingivitis according to the 2018 Classification of Periodontal and Peri-Implant Diseases and Conditions, without clinical attachment loss attributable to periodontitis.
• Have adequate oral hygiene (ranging from good to fair; score from 0 to 1.9 according to Silness and Löe plaque index (1964)
• Possess at least 28 natural teeth.
• Able to understand study procedures and provide written informed consent.
• Willing to comply with all study procedures, intervention instructions, and follow-up assessments.

Exclusion criteria

• Using braces and dental prosthesis.
• Presence of systemic diseases known to influence oral and periodontal health
• Use of antibiotics for the last 3 months or any medication or known to affect oral and periodontal tissues or salivary flow
• Moderate or high dental caries risk
• Severe tooth malposition that may interfere with plaque assessment or oral hygiene procedures
• Participants presenting with moderate - severe dentin hypersensitivity
• Participants with mucosa/ gingival trauma/recession and tooth wear
• Pregnancy or breastfeeding
• History of allergy or hypersensitivity to any material used in the study
• Cognitive, psychiatric, or physical conditions that may impair compliance with study procedures