Background: Application and development of oral health education (OHE) program is critical to recognize and to improve the risk of oral and dental health factors among adolescents. Aim: The purpose of the study was to evaluate the developments in the adolescents' oral health behavior and skills, in comparison with the pupils' situation before the teachers' training. Materials and Methods: Seven schools in the city of Diyala-Baquba participated in a randomized controlled experiment for this research. Eighty males and females aged 12 with good general health participated in this study over the course of 16weeks to evaluate the effects of a school-based OHE program on their oral hygiene, gum health, and halitosis. From the selected schools, one subjected to the intervention of OHE program and one of them was a control. A questionnaire was used to measure both general and oral health. In order to better prepare the teachers, a course lasting three days planned. To evaluate levels of oral hygiene, we used plaque indices, gingival indices, and halitosis scores to evaluate their breath. Results: Results showed that intervention school showed statistically significant improvements in student oral health indicators such plaque, gingivitis, and halitosis scores. Comparing teacher-led group to the controls and the baseline assessment, the former was found significantly lower scores for the plaque index, gingival index, and halitosis. There were significant differences discovered statistically (P< 0.01). Conclusions: School's children in the teacher-led OHE group showed significant improvements in their oral health, hygiene, gingival health, and oral malodor.