Background: The aim of the present study was to assess the incidence, severity, and extension of periodontal disease among young subjects.

Methods: Three hundred sixty subjects from a public school in Belo Horizonte, Brazil were examined. Forty-four subjects with bone loss (BL) and/or clinical attachment loss (CAL) ≥4 mm, and no dental care during the following 52 months, were considered the reference sample and were recalled for a second examination. At both examinations, statistical analyses were performed for CAL and BL for subject, tooth, and site. Comparisons of CAL at subject, tooth, and site levels were performed with the Wilcoxon test for matched samples. Comparisons of BL at subject, tooth, and site levels were performed with the McNemar and Student t tests for dependent samples.

Results: Findings indicated an increase in the number of sites with CAL >4 mm from baseline to follow-up. Sites that exhibited BL increased from 2.14% at baseline to 7.5% at follow-up (P <0.001). The severity of periodontitis was characterized by increased CAL values at affected sites at both examinations (P <0.001) and an increase in BL over time (mean BL at 35 affected sites was 2.6 mm at baseline and 3.5 mm at follow-up; P = 0.001). In addition, a 34% incidence of BL was verified.

Conclusions: The incidence, severity, and extension of CAL and BL were significant findings. They indicate the importance of early detection of the disease and the need for preventive health care programs geared toward young subjects.