Correlation between coronal and apical arch form and degree of divergence: a volumetric computed tomography analysis.

Abstract

Purpose: To determine the existence of any correlation between the degree of divergence and apical and coronal arch form using cone-beam computed tomography (CBCT).

Materials and methods: A total of 176 (88 coronal and 88 apical) CBCT scans pertaining to a sample of 44 subjects (16 males and 28 females), of which 26 were Class I, 14 Class II and 4 Class III, were analysed. A lateral projection of the skull was obtained from each VCT and cephalometric tracing was performed (according to Ricketts) so as to divide the sample into subgroups based on the degree of divergence (11 short-faced, 18 norm-faced and 15 long-faced subjects). Dahlberg's index values were calculated and Student's t-test for paired data was applied.

Results: On the whole, the hyperbolic cosine curve was found to be the most representative of the arch forms considered.

Conclusions: A correlation between degree of divergence and the arch form of the apical and, especially, coronal portions of both the upper and lower jaws was revealed.