Accuracy and reliability of 2D cephalometric analysis in orthodontics

Abstract

ObjectivesTo evaluate the accuracy of two-dimensional (2D) cephalometric analysis when compared to “gold standard” measurements on skulls. Also to appraise the reliability of 10 linear measurements commonly used in 2D lateral cephalometric analysis. MethodsTwenty dry human skulls and its digital lateral cephalometric images of were taken. The skulls were positioned in an aluminum filter box to mimic soft tissue attenuation. Ten linear measurements were performed both in skulls and radiographs by 2 observers (experienced dentomaxillofacial radiologists). The same procedure was repeated twice, with 1 month interval, to allow calculation of the intra- and inter-observer variability. ResultsStatistically significant differences were found between cephalometric and direct craniometric measurements. In general, measurements were on average lower in skulls with exception of three that were on average significantly higher (Co-Gn, Go-Me, Co-ANS). When a bilateral landmark was included, measurements were significantly higher. Furthermore, no significant differences were observed between measurements by the two observers (p<0.05). ConclusionRadiographic linear measurements systematically overestimated the direct linear measurements performed on the skulls. However, differences found were most often <1mm, which is generally within one standard deviation of “normal” values in conventional cephalometric analysis. It is assumed that such differences are often clinically acceptable, yet further studies are encouraged to evaluate the impact on cephalometry-based therapy planning.