| Objective: The three-dimensional(3d) craniofacial measurements were studied through the quantitative computed tomography(CT). The dynamic database of quantitative measurement of three-dimensional craniofacial bone was established as mandible in physiological position. Methods: 100 native adults were examined by spiral volumetric CT(Philips Tomoscan SR-7000). 21 children (age 8-15) were examined by mutislice helical CT(GE lightspeed Qxi). 3d craniofacial bone images were reformatted and 3d measurements were performed in Easy Vision Workstation and SUN Workstation respectively. 33 points were defined in the 3-d craniofacial structure in screen, 14 distances and 11 angles were measured, and 12 ratios were calculated in each case. All data were transferred into the database based on the SAS software packages. There is all information of one case (such as number, sex, age, distances, angles) in one row; each column is a measurement item. The mean, standard deviation, standard error, medium, coefficient of variation and 95% confidence interval of data can be calculated and the correlation, regression between several groups of measurement item can be proceeded by computer automatically in the dynamic database. Results: 3d craniofacial bone images were displayed in arbitrary views without disturbing superposition by using cutting, rotating and 3D measurement procedures. The large data volume provides more information of spacial relationship of skull base, zygomatic bone, maxilla, mandible and vertebra. The coefficient of variation of skull base is less than that of maxilla and mandible, The standard deviation of ratios is further smaller than the standard deviation of distances and angles. With stepwise regression, the equation is (Go-Go)Y=0.602X1+0.805X2+0.276X3-0.608X4-14.442 ; (Tz-Tz) :Y=0.812X1+0.178X2+0.339X3+0.106X4+30.178. The overall size of the cranio-orbito-zygomatic skeleton reaches 89% to 97% of adult size by age 8-15 years.
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