Oral clinical status and oral health-related quality of life: is socioeconomic position a mediator or a moderator?

Aim: To evaluate whether socioeconomic position exerts a mediating and/or moderating effect on the association between oral clinical measures and oral health-related quality of life (OHRQoL) in adolescents. Materials and methods: The study analysed data on 5,445 adolescents aged 15–19 years from the Brazilian Oral Health Survey (SBBrasil Project). The numbers of decayed and missing teeth, number of sextants with gingivitis and malocclusion were assessed through oral clinical examinations. Participant’s age, sex, OHRQoL and socioeconomic position were also collected. Monthly family income was used to indicate the participant’s socioeconomic position, and OHRQoL was assessed using the Oral Impacts on Daily Performance. Moderation was tested using Poisson regression models. Structural equation modelling and Sobel’s test assessed the mediation effects. Results: Oral clinical measures, OHRQoL and socioeconomic position were significantly correlated (P < 0.001). The moderator effect of socioeconomic position on the association between all oral clinical measures and OHRQoL was observed. The impact of all oral clinical conditions on adolescents’ OHRQoL was lower in the low-family-income groups compared with those with a better income. Socioeconomic position partially mediated the relationship between the four oral clinical measures and OHRQoL. Sobel’s test confirmed these findings (P < 0.001). Conclusions: The findings suggest the importance of socioeconomic position as a moderator and mediator factor between oral clinical measures and OHRQoL. Disadvantaged adolescents are likely to experience poor OHRQoL due to oral conditions. The reduction of the impact of oral conditions on quality of life in adolescents may be enhanced by addressing social inequalities related to oral health.