Development and its applications of three dimensional head model construction system utilizing frontal/lateral cephalograms and facial photographs.

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Three-dimensional visualization of human head has been frequently utilized for diagnosis and treatment of cranio-facial deformities in medical and denal area. Computed tomography can supply three dimensional image (3D-CT) ), but it needs large X-ray exposure. The present study aimed to construct individual 3D head model using ordinal head X-ray, facial photograph and dental cast.Computed tomography of the head and dental cast were taken from volunteers of adult males (11 subjects) and females (10 subjects). Three-dimensional coordinates of selected anatomical landmarks on the soft and hard tissue on 3D-CT images ware calculated and their averages were computed for both groups. The corresponding landmarks on ready-made head model (Viewpont, Co. Ltd, USA) were fitted to these mean coordinates. Thus, the standard Japanese adult male/female head models were obtained. To represent an individual model, we introduce a model-based construction method using photogrammetric shape extraction from X-ray and facial images of patient in order to modify standard facial/skeletal models. The dental shape is also modified by digitizing dental cast. This new method is possible to reproduce three dimensional integrated model on a personal computer and view the structure from any desired angle.As a clinical applications, this new method was employed to perform computer simulation for patients with mandibular prognathism who underwent saggital splitting ramus osteotomy. The simulated postoperative skeletal/facial images ware similar to the actual ones obtained after surgery. It will provide easy-to-understand information about treatment to the patients.