The aims of this study were to evaluate, by means of 3D software, any correlation between ethnic group and the shape and size of the dental arcade and its bony support, and to investigate the correspondence between the latter two variables within each ethnic group. The data gathered were also compared with the measurements of commercially available pre-formed archwires to determine which provide the best fit for each arch in each group.

The shape and size of the dental and alveolar arches of 29 subjects of African origin and 37 Caucasian subjects were compared in terms of linear inter-canine, inter-premolar and inter-molar measurements, overall arch length, and the distance between each tooth and the reference occlusal plane. To determine which pre-formed archwires are best suited to each of the two ethnic groups, the in-out of the brackets was considered, simulating their presence in the oral cavity.

The upper and lower dental and alveolar arches were all wider and longer in African with respect to Caucasian subjects (P<0.05). In general, “Roth small” (index value 1.556) and “Ideal Form Medium” (index value 0.645) archwires were better suited to both upper and lower arcades in the latter group, while “Damon” (index value 1.447) and “Ideal Form Large” (index value 1.695) conformed better to the size and shape of both arcades in the former.

There are very significant differences in arch form between the two ethnic groups considered, and the range of pre-formed archwires on the market does not provide for the anatomical variability of patients.