Asymmetrical Eruption of Permanent Teeth in Australian Aborigines

Abstract

A better understanding of the factors influencing tooth eruption is important given the association between altered eruption patterns and crowded or decayed teeth. Hence, the aims of this study were to quantify the extent of asymmetry in tooth eruption and to determine whether eruption asymmetry was significantly influenced by sex, tooth position or timing of emergence. Additionally, directionality of asymmetry and variation between ethnic groups were also explored. Data collection was based on the examination of serial dental casts from a sample of 90 Aborigines (50 male, 40 female) aged 6 to 18 years from the Yuendumu settlement in the Northern Territory of Australia. These casts were obtained at yearly intervals from the 1950s to the early 1970s. Tooth antimeres on each cast were compared using a 4-grade eruption score. Relatively high (> 70%) inter and intra-observer concordances confirmed reliability of the recording system. Asymmetry frequencies were calculated and associations between variables assessed using chi-square analyses, with statistical significance set at alpha = 0.05. Evidence of patterned asymmetry for permanent tooth eruption was noted among the sample of Australian Aborigines, with the distally positioned, later forming teeth showing the highest levels of asymmetry.