New standards for permanent tooth emergence in Australian children.

BACKGROUND: Published standards for permanent tooth emergence in Australian children are 40 years old. The aim of this study was to present new data on the timing and sequence of permanent tooth emergence in a large sample of Australian children and to compare the findings with those of earlier studies.
METHODS: Records of a randomly selected sample of 8676 children, aged between 4 to 16 years, who had attended the clinics of the South Australian Dental Service were scanned optically and coded to provide the data for this study. A logistic regression analysis enabled median times of emergence, together with percentile ranges, to be calculated for each tooth, except third molars, in boys and girls. Comparisons were made between the sexes and with previously published values. The frequencies of occurrence of emergence polymorphisms for different tooth pairs were also computed.
RESULTS: The earliest teeth to emerge in both boys and girls were the central incisors and first molars, whereas the second premolars and molars and maxillary canines tended to be last to emerge. The mandibular teeth tended to precede the corresponding maxillary teeth in emergence in both sexes. Tooth emergence was advanced in girls compared with boys, averaging 4.5 months in the maxilla and 5.3 months in the mandible. In general, emergence times of children in the present sample were later than those reported previously for Australian children. The most common emergence polymorphism in the maxilla involved the canine and second premolar, whereas common polymorphisms in the mandible were noted for the central incisor and first molar, canine and first premolar, and the second premolar and second molar.
CONCLUSIONS: Given that they have been collected relatively recently from a large sample of children, the new data reported in this paper can now be used as standards when assessing permanent tooth emergence of Australian children.