September 2012

Objective: The present study hypothesised that interventions based on the Precaution Adoption Process Model (PAPM) are more effective than the conventional approach in modifying oral hygiene behaviour in adolescents. Method: A stratified random sampling method was used with subject groups (classrooms) randomly allocated to a control or to one of intervention groups (conventional instruction or PAPM). Short-term and long-term results were assessed after 3 and 12 months. The study sample comprised 254 12-13 year olds whose plaque levels were assessed by two outcome measures, namely the Quantitative Plaque Percent Index and its derivative the Ratio of Plaque % Change. Results: Subject retention rate was 69%. The most substantial decrease in plaque scores was in the PAPM group (12% after 3 months, 18% after 12 months), while the smallest reduction was in the control group (4% after 3 months and 12% after 12 months). There was a trend of reduction in plaque levels (p<0.001) in all study groups from baseline to the 12 month follow-up. Conclusions: The intervention based on the Precaution Adoption Process Model was only slightly more effective in changing adolescent oral hygiene behaviour as compared to the conventional approach. The positive change in the control group was unexpected and needs further exploration. Key words: dental plaque index, adolescent, oral hygiene, health behaviour, Precaution Adoption Process Model