Purpose

This study aimed to investigate the effects of a peer-led oral health intervention based on the Health Belief Model and the Social Cognitive Theory on improving oral health among Hong Kong adolescents.

Methods

The study adopted a cluster-randomized controlled trial design, and 1184 students in 12 schools were randomized to intervention or control groups. After baseline assessment, the intervention group received a peer-led theory-based oral health intervention, while the control group received booklets for oral health promotion. Self-reported brushing and flossing, Health Belief Model/Social Cognitive Theory constructs, and oral health–related quality of life (OHRQoL) were measured at baseline, 6 months, and 12 months, and dental plaque accumulation and caries status were measured at baseline and 12 months. The trial was registered at https://www.clinicaltrials.gov (NCT03694496).

Results

Brushing, flossing, and OHRQoL improved more in the experimental group than in the control group at the 6-month follow-up compared with baseline (p < .001). The mean gain score difference was .81 for brushing, .47 for flossing, and -2.51 for OHRQoL. At the 12-month follow-up, the mean gain score of brushing frequency, plaque index, caries status, and OHRQoL were .18, −.28, −.32, and −2.79, respectively, which all sustained the significant difference (p < .001).

Conclusions

Our findings suggested that the Health Belief Model combined with Social Cognitive Theory in a peer-led intervention is effective to increase self-reported brushing frequency and improve oral hygiene status and OHRQoL among adolescents.