INTRODUCTION: Oral health is crucial during adolescence, yet many young individuals engage in suboptimal oral hygiene behaviors, contributing to oral health issues. While genetics may have some influence, lifestyle factors such as diet, preventive care, and oral hygiene practices play a more critical role in the development of dental caries. The World Health Organization recognizes oral health as a lifelong cornerstone of overall well-being. This study aimed to evaluate the effectiveness of a school-based educational intervention for improving oral health knowledge, attitudes, practices, and self-efficacy among female secondary school students in Kashan, Iran. METHODS: This randomized controlled trial was conducted in 2023 with 80 female students aged 12 years from two public schools at Kashan. The participants were selected via cluster sampling and randomly assigned to either the intervention group (n = 40) or the control group (n = 40). Data were collected at baseline, one month postintervention, and three months postintervention via a standardized questionnaire administered to both groups. The intervention consisted of four weekly 90-minute educational sessions led by a dentist and a health education specialist, with a focus on oral health knowledge, attitudes, practices, and self-efficacy. Additionally, the intervention group received a digital educational booklet, while parents were provided with a checklist to monitor their children's tooth brushing and flossing behaviors. The control group did not receive any educational intervention or a checklist for tracking oral hygiene behaviors during the study period. Dental plaque levels were assessed via plaque-disclosing tablets (PDTs) at baseline and three months postintervention. Data analysis was performed via SPSS version 24, which employs the chi-square test, Wilcoxon test, Mann‒Whitney test, and Friedman test. RESULTS: There was a significant difference between the intervention and control groups in all the measured variables after the intervention (p <
0.002). Postintervention, the intervention group demonstrated significant increases in mean scores for oral health knowledge (from 5.4 to 9.3), attitudes (from 55.6 to 62.1), self-efficacy (from 53.5 to 62.7), and practices (from 28.0 to 33.4) (p <
0.05). No significant changes were observed in the control group (p >
0.05). There was a significant difference between the intervention and control groups in all the measured variables after the intervention (p <
0.002). The average score of dental plaque was significantly different between the two groups (p <
0.002). The Wilcoxon test revealed that after the intervention, the test group had improved indicators, and the control group had increased dental plaque scores. CONCLUSION: The educational intervention effectively enhanced oral health knowledge, attitudes, self-efficacy, and practices among female students. The incorporation of such interventions into school health programs may promote long-term improvements in oral health behaviors among adolescents. TRIAL REGISTRATION: Clinical Trial Registry (IRCT code: IRCT20180827040889N1), registered on 27/01/2024.