Technical error of mesiodistal diameters for the permanent and deciduous dentition

Method errors and reliabilities are given for mesiodistal measurements of the permanent and deciduous dentitions. Method errors, describing random measurement error, range between 0.04 and 0.12 mm. Reliabilities, describing the proportion of true variance to true plus error variance, are lowest for measurements taken on the canines. Mesiodistal measurements of the incisors are more reliable than those taken on the (pre)molars. The different reliability estimates reflect disparities in true rather than error variance. The method error and reliability statistics serve different purposes and lead to different interpretations.