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The purpose of this study was to clarify the differences in the nature of craniofacial growth between subjects with normal occlusion and patients with unilateral cleft lip and palate (CLP) in terms of the size, shape and principal growth direction of craniofacial skeleton using finite element method (FEM). Lateral cephalograms were taken of 40 subjects as normal group and 178 patients as CLP group. These subjects were divided into seven developmental ages of 4-, 6-, 8-, 10-, 12-, 14- and 18-year-old. For the finite element analysis, the craniofacial complex was discretized into seven structures or elements with three nodal points in each after tracing each lateral cephalogram on acetate paper. For each stage, the growth parameters in CLP group were compared to those in normal group. The growth of upper facial skeleton and maxillary complex was more remarkably inhibited in CLP than in normal group. Especially, the growth inhibition of posterior maxillary complex in a vertical direction was remarkable in CLP group at any ages. Difference in the size and shape of entire mandibular skeleton between CLP and normal groups was not apparent. It is suggested that grow timing and peak velocity, an essential and key determinant to the success in orthodontic treatment, have been clarified in this study more clearly than in previous studies. It is hopefully anticipated to explore some key determinants to predict individual growth of the craniofacial skeleton near future.

The purpose of this study was to elucidate the nature of human craniofacial growth by means of finite element method (FEM), and to compare the results with the current concept derived from morphometric studies with roentgenographic cephalometry (RCM). Lateral cephalograms were taken of 20 males and 20 females, and traced on acetate paper. On the tracing, the craniofacial complex was divided into seven areas or elements. Growth analysis was executed with FEM for changes in the size and shape of each area during six developmental periods from 4 to 18 years old. The size change in the male group exhibited a peak from 10 to 12 years old for the cranial base and upper facial skeleton, from 8 to 10 years old for the maxillary complex, and from 12 to 14 years old for the mandible. On the other hand, in the females, the size change was almost invariable from 4 to 12 years old and completed suddenly at 12 years old, which was earlier by a few years than in the males. An interesting finding is that changes in the size and shape were the most substantial in the maxillary complex, followed by those in the mandible, and the smallest in the cranial base and upper facial skeleton. It is shown that growth of the cranial base lasted up to 14 years old and the maxillary complex exhibited the greatest growth changes in the size among various anatomic structures. These findings may provide a new concept of human craniofacial growth, somewhat different from the previously established principles by RCM.