Hypodontia: an epidemiologic study of American black and white people.

INTRODUCTION: There are numerous epidemiologic studies of hypodontia, but most focus on white populations that, because of small teeth and slow development, might not represent the status of other peoples. The purpose of this study was to contrast the distributions of hypodontia in an adolescent sample of American blacks (n=600) with a comparable sample of whites (n=1100).
METHODS: Panoramic radiographs of 1700 unrelated adolescents between 12 and 18 years were scrutinized for hypodontia. Those with syndromes and major genes contributing to congenital absence were omitted.
RESULTS: The prevalence of people with missing teeth is significantly lower in blacks (11%) than in whites (27%), as is the number of missing teeth per person. When all tooth types were combined for a summary value, the frequency of missing teeth in whites (1.5% of the expected 32 teeth per person) was significantly higher than in blacks (0.6%), with an odds ratio of 2.52 (95% confidence limits [CL]: 2.07, 3.08). Differences between black and white people are disproportionately large where hypodontia is most common, notably in 2 tooth types: (1) the difference is statistically significant for third molars, with the odds ratio 3.18 higher in whites (CL: 2.43, 4.17) for all quadrants combined, and (2) for second premolars (combining all quadrants), whites are 1.75 times more likely to exhibit congenital absence (CL: 1.06, 2.90). In contrast, significant sex differences were found only for the third molars (absence more common in females), and the sex differences were greater in whites than in blacks.
CONCLUSIONS: Extrapolations from the literature, based largely of studies of white subjects, do not readily apply to American blacks or, potentially, to other racial groups.