Morphological relationship between the cranial base and dentofacial complex obtained by reconstructive computer tomographic images.

The aims of this study were to investigate the relationships between the cranial base, including the glenoid fossa and maxillofacial morphology, obtained by three-dimensional (3D) computed tomography (CT). The specimens were 45 Skeletal I and Skeletal II dry skulls of modern Japanese males without marked crowding, anterior crossbite, or maxillofacial asymmetry, which had been preserved in the Tokyo University Museum. To examine the differences in the cranial base and maxilla between two groups classified by the median value of N line-A [N defined as a perpendicular line to Frankfort horizontal (FH) through point N, and N line-A as the distance between N and point A]. The specimens with an N-A line less than 1.5 mm were classified as the small group, and those with an N line-A more than 1.5 mm as the large group. Correlation coefficients showed that S-SE was positively related to N-Ba, S-N, S-Ba, and angleFH to S-Ba, and negatively related to SE-N. Ba-X, Ba-Y and Gf-X showed positive correlation with S-Ba and angleFH to S-Ba. For the small group S-SE was longer, angleFH to S-Ba was larger, and Ba-X, Gf-X, A-X, ANS-X, and PNS-X located more posterior and in addition more inferior in ANS-Y. The evidence suggests that S-SE, which is a main component factor of the anterior cranial base, and the antero-posterior position of glenoid fossa, is related to the position of the maxilla. The length and inclination of the posterior cranial base, which is related to Ba, influenced the position of the glenoid fossa.