There is a relationship between knowledge, attitude and practice of oral health care by gender and grade: Compared to grade 6 students, grade 7 has good oral health care practice by 0.59 times (95% CI: 0, 36 - 0, 99), grade 8 students by 0.52 times (95% CI: 0, 31 - 0, 87) and grade 9 students with only equal 0.47 times (95% CI: 0, 25 - 0, 87).