The displacement of craniofacial reference landmarks during puberty: a comparison of three superimposition methods.

In this study, the amount and direction of displacement of reference landmarks located on the cranial base and face were examined and compared according to the superimposition methods of Björk (method A), Steiner (method B), and Ricketts (method C). The material consisted of cephalometric and hand-wrist films of 40 nontreated growing individuals obtained at the beginning (T1) and at the end of the observation period (T2). Hand-wrist films were used to evaluate the skeletal maturation of the subjects. The displacement of each landmark was measured according to each superimposition method, and the amounts of displacement in each method were evaluated by paired t-test. The repeated measurement analysis of variance test was used to compare the variances of the changes among the methods. Significant changes were observed in landmarks (sella, nasion, basion, pterygomaxillare), which used as references for superimpositions. The direction of displacement of sella and pterygomaxillare points was different among the methods. In the horizontal plane, although most landmarks were displaced in a similar manner in the Björk and Ricketts methods, the vertical displacement of all the landmarks was different. The horizontal displacements of basion, condylion, and gonion were similar according to all three methods. These results indicate that differences regarding the superimposition methods should be taken into consideration in the evaluation of the changes due to growth or treatment.