Dental arch form in three Pacific populations: a comparison with Japanese and Australian aboriginal samples.

The purpose of this study was to provide information about arch shape variations among South Pacific populations. The application of Fourier transforms, Y(phi i) = ao/2 + sigma (aicos phi i + bisin phi i) was used to separate two components of variation; size and shape. Dental arch size can be described by one coefficient (ao), while the shape can be summarized by the first three harmonics (amp1-3) in the Fourier series. The materials used in this study were dental casts of South Pacific populations (Fiji, Western Samoa and Kiribati), Australian Aboriginals and Japanese. Fijians, Western Samoans and Kiribati people have larger upper and lower dental arches than that of Japanese. These populations were separated by the arch size and first Fourier amplitudes which showed the arch depth/width ratio. The Fijian upper and lower dental arches were significantly larger than those found in other populations and was characterized by a wide posterior arch breadth. The Western Samoan and Kiribati arch shape was more similar to the Japanese arch shape than the Fijian. Distribution patterns of arch shape characteristics in these populations showed the same tendencies in the upper and lower arches.