Objectives:The effectiveness of one-to-one preventive dental education provided by dental undergraduate students for improving elementary school-aged children's oral self-care skills, diet-related knowledge, and diet behavior was tested. Methods:The sample consisted of 106 children between the ages of 5 and 12 years who attended the same school. Oral self-care skills were assessed by undergraduate dental students using a tooth-brushing assessment form, and diet knowledge and behaviors by means of a questionnaire. The effectiveness of education (two one-to-one sessions) was evaluated by measuring the posteducational changes in the children's oral self-care skills, diet knowledge, and behavior.Results: There were significant improvements in the means (sd) of toothbrushing skill scores (range: 0-18) from 6.2 (4.0) at the baseline to 8.4 (4.1) at the first and to 10.3 (3.0) at the second follow-up. Total tooth-brushing time (in seconds) significantly increased from 76.0 (59.1) at the baseline to 110.7 (74.3) at the first follow-up then decreased to 102.6 (73.1) at the second follow-up. The means (sd) of diet knowledge scores (range: 0-30) improved significantly from 18.5 (5.6) at the baseline to 23.0 (7.3) at the first and to 24.5 (4.0) at the second follow-ups. The means (sd) of weekly sugar intake scores (range: 0-18) significantly decreased from 4.9 (2.1) at the baseline to 3.1 (2.0) at the first follow-up and remained unchanged until the second follow-up. Conclusions: One-to-one dental education improved children's oral self-care skills, diet-related knowledge, and diet behavior. The post-educational improvements were maintained for 6 months in older children but not in the younger children. K E Y W O R D Scommunity-based dental education, dental hygiene, dental students, oral health education, school children, toothbrushing

BACKGROUND Oral health is fundamental to overall well‐being. As teens are at high risk for tooth decay, we require a unique approach to motivate them to maintain oral health. METHODS Sixty‐four adolescents (10‐13 years) were recruited from 2 schools. Oral health education was based on cooperative learning guided by the social determination theory (SDT) principles. Students' oral health knowledge and oral self‐care skills were assessed at baseline (before education), 3 weeks, and 6 months after the education. RESULTS Complete data were available for 51 students (follow‐up rate 79.7%). There were significant (p < 0.001) changes in the mean (SD) toothbrushing score from 10.1 (±6.3) (baseline) to 26.5 (±6.0) (follow‐up 1) and to 28.1 (±5.3) (follow‐up 2). The mean (SD) tooth brushing time significantly (p < 0.001) increased from the baseline of 84.0 (±43.5) to the first follow‐up to 107.0 (±39.8) and to 102.3 (±33.1) at the second follow‐up. The mean (SD) diet knowledge scores significantly (p < 0.001) increased from 8.2 (±2.1) at the baseline to 10.2 (±2.7) at the first follow‐up and remained the same at the second follow‐up. CONCLUSION Social determination theory‐guided cooperative learning was efficient in improving student oral health‐related knowledge and oral self‐care skills, and this improvement was maintained for 6 months after the discontinued education.