Changes in radiographic bone level in orthodontically treated teenagers over a 4-year period.

In 1984 the prevalence of subjects with radiographic bone loss was assessed in all 14-year-old schoolchildren in Oslo (n = 2767). An overrepresentation of subjects with bone loss was found among those undergoing orthodontic treatment. The aim of the present study was to assess the effect of orthodontic treatment on the prevalence and incidence of radiographic bone loss during the following 4-yr period. Bitewing radiographs from 1984, 1986, and 1988 of a sample of 438 subjects from the original population constituted the study material. Bone loss was recorded if the distance from the alveolar crest to the cementoenamel junction exceeded 2 mm. 111 subjects (25.3%) had received orthodontic treatment. In 1984, 18 of them (16.2%) exhibited bone loss. The corresponding figure for the 327 non-treated children was 14 (4.3%). The incidence of subjects with new tooth sites with bone loss among those with a record of previous orthodontic treatment was 1.1% and 3.2% in the periods 1984-86 and 1986-88, respectively. Among those who had never received such treatment the incidence figures were 3.2% in the period 1984-86 and 2.0% in the last period. The results indicated that the majority of the bone loss observed during or immediately after termination of orthodontic treatment was transient in nature.