Generation of the Midfacial Plane Out of CBCT Database

摘要

Nowadays we give much importance on positioning the head as far as possible in the natural position, for the purpose of the orthodontic/orthognathic diagnosis using lateral headplates. In case of CBCT (Cone Beam Computed Tomography) the head is fixed at several points in general and in most of the cases the patient is recorded in an unnatural position. Some authors accept these uptakes in this fixed position as ..natural" while others solve the problem by volume tomogram visualizing computer programs which convert the position in situ into the database-created form. That means the database is rotated into the right position aligned to space, respectively according to the cephalometric plane. In literature we can find some methods solving this, but these essays are solely using conventional orthodontic measuring points. In our work we looked for anatomical measuring points that can replace the conventionally used points which determine the orthodontic plane of the skull by using a combination of conventional and nonconventional points. When making cephalometric analyses and reconstruction-models for traumatology cases, these measuring points that determine the conventionally used plane in orthodontics are often missing or injured due to trauma. Thereby with the help of CBCT record a lot of anatomical formulas can be shown, that by conventional lateral and frontal headplate can not or just improperly be visualized. We determined the sagittal midplane with the help of anatomical landmarks. According to our results the analyzed formulas are acceptable to define orthodontic planes in cases of traumatology patients. During our analyses the CBCT gives us the possibility to use more than only the conventionally used measuring points. In our computer program we tried to apply different point triads to determine the midfacial plane for traumatology cases. During our work we used this facial midplane to diagnose the injuries of asymmetrical faces.