Statistical analysis
Caries, caries
CARIES, CARIES
All data from clinical examination and questionnaires were analyzed using the SPSS version 22.0 released 2013 (IBM SPSS Statistics for Windows, Armonk, NY: IBM Corp). Descriptive statistics were used for reporting demographic variables. In the control and intervention groups, the Oral Hygiene Index Simplified (OHI-S) and Caries Assessment Spectrum and Treatment (CAST) were evaluated at baseline and one-year follow-up. The questionnaire data including oral health related knowledge, attitude and self-reported behavior were analyzed. The Generalized Estimating Equation (GEE) with exchangeable correlation matrix was used to consider the cluster effect of school and time. In this analysis, the school code was considered as a “subject variable” and the student code and time were considered as the “within-subject variables”. In the GEE analysis, a linear model was used for quantitative outcomes (oral hygiene, knowledge, attitude, and self-reported behavior in relation to oral health), and a binary logistic model was used for the qualitative outcome (CAST index). In addition, in this analysis, time and intervention were considered as independent variables (predictors). The oral hygiene, caries, and oral health related knowledge, attitude and self-reported behavior considered as outcome variables. The models were examined considering the intervention × time interaction. The significance level was set at 0.05.