An epidemiological, observational, cross-sectional study was designed. Data collection was accomplished by
an intraoral observation to assess dental caries and a questionnaire, for collecting data related with oral health
behaviors and socio-demographic variables. The sample was constituted by children who attended the
twenty-seven primary schools, of the town of Sátão, localized in the Central Region of Portugal. All students,
from the selected schools, were eligible to participate in the study, since they attended primary school and
were aged between 5 and 12 years old, obtaining a final sample of 605 children participating in the study
(50.4% female).
The intraoral assessment was performed using a dental mirror and the WHO probe, and based on the
diagnostic criteria recommended by the World Health Organization (World Health Organization, 2003b).
The results were registered in the students in a individual oral status form and, for each child, was calculated
the number of decayed teeth, missing due to caries and filled/restored due to dental caries for primary teeth
(dmft) and permanent teeth (DMFT). Then, the dmft and DMFT index were calculated, consisting of the
sample’s total average number of tooth surfaces decayed, missed and filled. By determining the dmft and
DMFT index, we can define four levels of dental caries prevalence severity: