Dental arch shape and size in Malay schoolchildren with Class II malocclusion.

Aim: To quantify and localise differences in Class I and Class II dental arches in Malay schoolchildren.

Methods: The subjects were 50 Malay schoolchildren (Mean age: 15 + 0.7 years) with either Class I (N = 25) or Class II (N = 25) malocclusions. Fourteen homologous landmarks on the upper and lower study models of the subjects were digitised using MorphoStudio software, and the Procrustes means were computed. The mean Class I and Class II configurations were subjected to ftests and finite element analysis.

Results: Normalised upper arch Class I and Class II configurations were statistically different (p < 0.05), but the lower arches were not. However, normalised Class II linear parameters were statistically smaller in the upper arch and larger in the lower arch. The upper Class II dental arch was narrower by 15 per cent and asymmetric changes in size (11-20 per cent) were localised in the labial and buccal regions of the lower Class II arch.

Conclusions: Size and shape differences between Class I and Class II dental arches can be identified with finite element analysis.