Introduction and objective:
The aim of the study was investigation of the effect of simple prophylactic methods on the motivation for concern about oral hygiene among 13–15-year-olds.

Material and methods:
The study covered 98 children from 4 groups attending junior high school. Adolescents from 3 groups were randomly qualified for conducting prophylactic procedures, while the fourth group constituted the control group. Three examinations were performed: preliminary and check-up examinations after 4 and 12 months. The state of the teeth and periodontium and the frequency of brushing of teeth were evaluated.

Results:
After 4 months, an increase in the number of decayed teeth was observed in all groups; in the control group it was significantly higher compared to the groups subjected to prophylactic actions. After 4 months in the groups covered by prophylactic actions, a significant decrease was obtained in the number of adolescents with CPITN > 0. In the examinations performed after 12 months, no significant differences were found in the value of the DMF and the CPITN index in the examined groups. In both examinations, after 4 and 12 months, the declared frequency of brushing teeth increased, especially in the group which had been provided individual instructions concerning oral hygiene.

Conclusions:
1) Implementation of prophylactic methods resulted in an improvement in the state of oral health among junior high school adolescents. 2) Prophylactic actions should be regularly repeated. 3) The provision of individual instruction with supervised individual teaching of brushing teeth resulted in an improvement in the motivation for concern about oral hygiene.