Differences in cephalometric reference values between five centres: relevance to the Eurocleft Study.

Cephalometric data from five different geographical areas (Oslo, Manchester, London, Nijmegen, and Michigan) were compared. The angles SNA, SNB, and ANB were taken from published tables in the form of mean, standard deviation (SD) and number in the sample, divided up by age and sex. Angles SNA and SNB were significantly different among centres on univariate analysis. The Oslo data showed 23 instances in which they differed significantly from the other data, London 16, Manchester 11, Nijmegen 11, and Michigan 7. Multivariate analysis using Penrose distances were Oslo (2.04), Manchester (1.39), London (0.93), Nijmegen (0.80), and Michigan (0.66). The sums of the Mahalanobis distances were Nijmegen (3.60), Oslo (3.10), London (2.80), Manchester (2.25), and Michigan (1.49). As these results probably reflect racial and genetic differences, these must be taken into account when international comparisons are being made, as in the Eurocleft study.