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.

Natural craniofacial changes in the third decade of life: a longitudinal study.

The aim of this study was to evaluate longitudinally the natural craniofacial and dentoalveolar changes that occur in the third decade of life. Natural head position lateral cephalometric films and dental casts of 30 people (14 women and 16 men) were evaluated. The mean age at the beginning of the observation period was 22.35 years for the women and 22.19 years for the men, and the observation period was approximately 10 years. Cephalometric films were superimposed by the structural method, and the measurements of the dental casts were made with a digital caliper. All tracings were digitized, and changes in the 65 cephalometric and 10 dental cast measurements were evaluated statistically. In this early adult period, small changes were found in the craniofacial and craniocervical parameters; the changes were more significant in the women. The most significant changes were found in the vertical dimension. The total anterior face height increased in both genders, while the lower anterior face height increased significantly in the female group. Soft tissue measurements reflected the vertical skeletal changes. The retrusion of the upper lip was significant in the women, and the upper lip thickness decreased in both genders. In the dentoalveolar region, the main movement was eruption of the teeth. The overbite amount increased significantly only in the female group. All dental arch measurements decreased in both sexes. The decrease in the mandibular arch length discrepancy was significant in the men. These findings have important clinical implications regarding the long-term stability and retention of orthodontic and orthognathic surgery treatment results.