[A study on growth and development of maxillofacial region with vector analysis]

In order to observe the maxillofacial growth and development quantitatively, the vector analysis was applied in this study to divide Y axis,which is advocated in Downs method,into horizontal section and vertical one,from which the ratio of the facial growth separately in anterior and inferior direction was obtained.75 pieces of x ray films for various dental stages of Shanghaiese with normal occlusion were selected and their angle of Y axis together with their cotangents were measured. The results showed that the cotangent of those with mixed,early permanent and permanent dentition were separately 0.47,0.48 and 0.45 indication that there was a certain relationship between anterior direction and inferior one for the maxillofacial region growth and development.