Marginal bone loss in the primary dentition. A survey of 7-9-year-old children in Sweden

The present study was designed to determine the prevalence of bone loss in the primary dentition of children. Radiographs from children aged 7-9 were collected from 25 out of a total of 26 Public Dental Clinics in the County of Orebro, Sweden. These radiographs, representing 36.0%, 50.3% and 48.7% of all 7-, 8- and 9-year-old children (n = 8666) living in the districts of the participating clinics, constituted a primary sample. In addition, the 9-year-olds were subjected to a more comprehensive sampling procedure to obtain a more complete sample (sample of 9-year-olds), resulting in a group of 2017 children (71.9%). The radiographs were evaluated with respect to presence of marginal bone loss (CEJ-MBL: distance between the cemento-enamel junction and the marginal bone level > 2 mm), proximal calculus and number of decayed and filled proximal surfaces (dfsp) in the posterior areas of the primary dentition. In the primary sample, the prevalence of bone loss for > or = 1 proximal surfaces of the primary dentition in the 7-, 8- and 9-year-old children was 2.0%, 3.1% and 4.5%, respectively. The corresponding figures for proximal calculus were 2.5%, 3.1% and 4.2%. Mean number of dfsp amounted to 2.3, 2.5 and 3.0. The prevalences of bone loss and proximal calculus as well as the mean number of dfsp in the sample of 9-year-olds corresponded to the findings for the 9-year-old children in the primary sample.