A radiographic study of the calcification and eruption of the permanent teeth in Inuit and Indian children

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Trodden, Bonnie Joy.
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The purpose of this multidisciplinary study is to determine the mean age and range of variation for the calcification and eruption of the permanent teeth in Native Canadian populations, and to determine whether there are significant differences between these populations and other North American native and North American White populations. As more Canadian Inuit and Indian patients seek comprehensive dental treatment, including orthodontics, the recognition of significant genetic and environmental differences in the development of the permanent dentition could facilitate the timing and the type of dental treatment selected. As well, variations in the timing of calcification and eruption of the teeth are extremely relevant to the identification and the assessment of age and sex of skeletal material, for both anthropological and forensic purposes. At the present time, all skeletal remains are compared to Caucasian standards of dental development, particularly gingival emergence. Panoramic data for this cross-sectional study was obtained from several clinical sources in Manitoba. All of the permanent teeth were studied, using twelve stages of calcification modified from Nolla (1960) and Moorrees et al. (1963). As well, four stages of eruption were considered, modified from Massler and Schour (1941). The mean age for each calcification score was found to be younger in both the Inuit and Indian samples, compared to studies of White populations, for all teeth except the premolars and second molars. Calcification occurs earlier in Inuit females than males in certain teeth. Indian females were clearly advanced in calcification over Indian males. A Dental Calcification Index was calculated using Nevile's (1973) formula in order to derive a dental age from the mean ages of calcification for each subject. A high correlation was found between the dental age and the chronological age. The result of this study show that while there are slight genetic differences resulting in earlier eruption of certain teeth, particularly in the Inuit sample, the primary cause of differences in the timing of eruption is the premature loss of the deciduous teeth. There is also a significant time lag between the mean age of alveolar and gingival emergence for each sample, which varies for each tooth. Thus, clinical standards for gingival emergence do not accurately predict the mean age of alveolar emergence. An Eruption Index has been developed to more accurately predict age in skeletal material from the age of alveolar emergence.