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Thin-plate spline analysis of the cranial base in subjects with Class III malocclusion

1997; Oxford University Press; Volume: 19; Issue: 4 Linguagem: Inglês

10.1093/ejo/19.4.341

1460-2210

Gagandeep Singh, James A. McNamara, Scott Lozanoff,

Cleft Lip and Palate Research

The role of the cranial base in the emergence of Class III malocclusion is not fully understood. This study determines deformations that contribute to a Class III cranial base morphology, employing thin-plate spline analysis on lateral cephalographs. A total of 73 children of European-American descent aged between 5 and 11 years of age with Class III malocclusion were compared with an equivalent group of subjects with a normal, untreated, Class I molar occlusion. The cephalographs were traced, checked and subdivided into seven age- and sex-matched groups. Thirteen points on the cranial base were identified and digitized. The datasets were scaled to an equivalent size, and statistical analysis indicated significant differences between average Class I and Class III cranial base morphologies for each group. Thin-plate spline analysis indicated that both affine (uniform) and non-affine transformations contribute toward the total spline for each average cranial base morphology at each age group analysed. For non-affine transformations, Partial warps 10, 8 and 7 had high magnitudes, indicating large-scale deformations affecting Bolton point, basion, pterygo-maxillare, Ricketts' point and articulare. In contrast, high eigenvalues associated with Partial warps 1–3, indicating localized shape changes, were found at tuberculum sellae, sella, and the frontonasomaxillary suture.