The relationship between the cranial base and jaw base in a Chinese population.

Introduction: The cranial base plays an important role in determining how the mandible and maxilla relate to each other. This study assessed the relationship between the cranial base and jaw base in a Chinese population.

Methods: This study involved 83 subjects (male: 27; female: 56; age: 18.4±4.2 SD years) from Hong Kong, who were classified into 3 sagittal discrepancy groups on the basis of their ANB angle. A cephalometric analysis of the angular and linear measurements of their cranial and jaw bases was carried out. The morphological characteristics of the cranial and jaw bases in the three groups were compared and assessments were made as to whether a relationship existed between the cranial base and the jaw base discrepancy.

Results: Significant differences were found in the cranial base angles of the three groups. Skeletal Class II cases presented with a larger NSBa, whereas skeletal Class III cases presented with a smaller NSBa (P<0.001). In the linear measurement, skeletal Class III cases presented with a shorter NBa than skeletal Class I and II cases (P<0.01). There was a correlation between the cranial base angle NSBa and the SNB for the whole sample, (r=-0.523, P<0.001). Furthermore, correlations between SBaFH and Wits (r=-0.594, P<0.001) and SBaFH and maxillary length (r=-0.616, P<0.001) were more obvious in the skeletal Class III cases.

Conclusions: The cranial base appears to have a certain correlation with the jaw base relationship in a southern Chinese population. The correlation between cranial base and jaw base tends to be closer in skeletal Class III cases.