Abstract:

Objective　To explore and establish a three-dimensional anatomical measurement method and diagnostic criteria for the jaw protrusion deformity.　Methods　We established a computer-aided three-dimensional measurement of jaw protrusion deformity after comparatively analyzing the data of cephalometric piece for 14 volunteers.　Results　①On the median sagittal plane, the connection between nasion and anterior alveolar seat point (NA), between nasion and inferior alveolar seat point(NB), and between eye and ear plane(FH) were firstly established. Then the angle α (between NA and FH), and the angle β (between NB and FH) were established to reflect the relationship between the maxilla and the mandible for the location of the skull. We initially established the diagnosis criteria for the angle α (88°~93°) and the angle β (87°~90°). ②Statistical data showed that, there was no significant difference between two-dimensional and 3D measurement of normal human jaws, but there was significant difference between those two methods in abnormal human jaws.　Conclusions　The computer-assisted construction of jaw protrusion deformity and three-dimensional anatomical measurement is feasible, which reflects the relations of lines and surfaces of three-dimensional spatial relations, improves the accuracy of the diagnosis, and provides an objective basis for diagnosis and treatment of jaw deformity. 

Key words: Maxillary and mandibular protrusion deformity, Three dimensional anatomical measurement, Digital medicine