A facial growth analysis based on FEM employing three dimensional surface measurement by a rapid laser device.

Abstract

Although there have been several studies of finite element method (FEM) analysis on two dimensional (2D) facial growth with cephalometric X-rays, there has been little FEM analysis on three dimensional (3D) facial growth of long term observation. Therefore the objective of our study is to use FEM model by 3D surface measurement of rapid laser device from human dried skull and to analyze the changes of facial growth based on FEM by the volume and the direction of strain in each stage. Samples were taken from each human dried skull for 5 stages; about 0, 3, 6, 9, 12 and 18 years of age, a total of 6 normal human dried skulls. (No abnormal skeletal growth patterns were selected and age was supposed by tooth development and eruption.) After measuring each human dried skull by 3D rapid device, we selected the clearest 16 anatomical reference points from about 70,000 points on face image to form accurate FEM shells. The study utilized Cosmos/M (SRAC) for FEM analysis, on a PC(NEC). From the strain analyses, it was revealed that (1) The vale of growth strain from 0 to 3 years of age and from 3 to 6 years of age gradually increased from condylar area toward mental area and the most vale of growth strain was showed at mental area. The vale of growth strain of corpus area was bigger than other areas. (2) As a whole the vale of growth strain of other areas except mental, corpus and nasal area were almost equal. The results indicate especially the growth change of mandible were predominantly showed in the early stages, and the direction of growth strain changed backward and above from mental area to condylar area.