This study aims to evaluate the effectiveness of a novel psychologic-based oral health instruction program (OHL program) by comparing oral health behaviors (OHB) and plaque index (PI) scores between intervention and control groups at three key time points-pre-intervention, post-intervention, and follow-up-enabling a comprehensive assessment of the intervention's impact and and persistence over time. The study hypothesizes that (1) the OHL program will lead to greater improvements in OHL compared to a traditional control group and (2) these effects will be sustained through the follow-up period.

Participants in the intervention group received the OHL program, while those in the control group received traditional oral hygiene instruction. Both groups had data collected at baseline, post-intervention, and at a 3-week follow-up.

The outcomes were oral health behavior (OHB) and plaque index (PI), compared at three time points: baseline (initial), post-intervention (final), and at a 3-week follow-up. Additionally, as a manipulation check, oral health literacy (OHL) levels were assessed at all three intervals.

Demographic information, OHL, and OHB were measured using standardized questionnaires from previous research. The 31-item OHL scale assessed five elements: 1) access, 2) understanding, 3) evaluation, 4) application, and 5) communication of oral health information and services. A 14-item scale evaluated OHB across three domains: 1) oral hygiene practices, 2) dietary choices, and 3) utilization of dental services.

In addition, clinical assessments of plaque were conducted using the Silness and Löe plaque index (PI, 1964). Plaque was evaluated on four surfaces of each tooth (mesial, distal, buccal, and lingual) using a WHO probe. Scores ranged from 0 to 3, reflecting the absence to a large amount of plaque accumulation, based on their established criteria. A single oral examiner recorded the plaque scores for each surface, and the average score for each tooth was calculated. The total score was then summed and divided by the total number of teeth examined, providing an overall plaque index for each individual. There were no outcome changes after trial commencement.

Inclusion Criteria:

• participants undergoing fixed orthodontic treatment, free from non-communicable chronic diseases (such as diabetes mellitus, hypertension, and heart disease), capable of reading, writing, and providing informed consent, and willing to participate in the oral health program.

Exclusion Criteria:

• reluctance to provide health information, inability to complete assessments, or withdrawal from the program at any stage.

All IPD that underlie results in a publication

Beginning 3 months and ending 1.5 years after the publication of results

Permitted researchers will be able to access the IPD and supporting information. They will be allowed to receive the Study Protocol and Statistical Analysis Plan (SAP). Researchers must request permission from me first.