Reliability of two methods for measurement of alveolar bone level in children

To determine the intra- and interexaminer reliability of two methods (calliper and computerized images) for measuring the alveolar bone level on bitewing radiographs of pre-school children and to determine the extent to which one method can measure more sites.

Standardized paediatric bitewings were analysed with either an image analysis program (ImageTool) or a digital calliper (Digimatic Caliper). With each method, radiographs were measured three times by three trained examiners. The differences in the number of sites measured with the two methods were assessed with McNemar's tests and kappa statistics. Reliability was assessed with paired t-tests, intraclass correlation coefficients (ICCs), Bland-Altman and survival-agreement plots.

The kappa statistics and McNemar's test indicated that examiners measured 14% fewer sites using ImageTool. Paired t-tests also demonstrated a statistically significant bias (range 0.11-0.23 mm) indicating larger measurements for this method, although these observed differences were considered clinically unimportant for the detection of 2 mm of bone loss (which was considered the threshold for periodontal disease). Intra- and interexaminer reliability (ICC range: 0.87-0.97) was considered good for both methods.

Reliable methods to assess alveolar bone loss in primary teeth are important for the diagnosis of incipient periodontal diseases. Both studied methods proved to be reliable. With the Digimatic Caliper, however, more sites were measured.