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.

An epidemiological study of hyperdontia in American blacks and whites.

OBJECTIVE: To test the null hypothesis that American blacks do not have a higher frequency of extra permanent teeth than whites. MATERIALS AND METHODS: Panoramic radiographs of adolescent orthodontic patients, either American whites (n = 1100) or American blacks (n = 600), were reviewed systematically. RESULTS: The frequencies of supernumerary incisors, premolars, and molars were each significantly more common in blacks. While incisors are the most common extra teeth in whites (and extra molars are least common), just the opposite ranking occurs in blacks. Overall, the odds ratio was 8.8 (95% confidence limits = 3.9, 20.0), confirming that American blacks are significantly more likely (almost 9 times more likely) to possess extra permanent teeth than American whites. CONCLUSIONS: The hypothesis is rejected. Both the frequencies and the patterns of extra permanent teeth are significantly different in blacks and whites, suggesting different frequencies of the relevant (but unidentified) factors governing the developmental mechanisms that result in hyperdontia.

Comparison of Amount of Primary Tooth Reduction Required for Anterior and Posterior Zirconia and Stainless Steel Crowns.

PURPOSE: To determine if aggressiveness of primary tooth preparation varied among different brands of zirconia and stainless steel (SSC) crowns. METHODS: One hundred primary typodont teeth were divided into five groups (10 posterior and 10 anterior) and assigned to: Cheng Crowns (CC); EZ Pedo (EZP); Kinder Krowns (KKZ); NuSmile (NSZ); and SSC. Teeth were prepared, and assigned crowns were fitted. Teeth were weighed prior to and after preparation. Weight changes served as a surrogate measure of tooth reduction. RESULTS: Analysis of variance showed a significant difference in tooth reduction among brand/type for both the anterior and posterior. Tukey's honest significant difference test (HSD), when applied to anterior data, revealed that SSCs required significantly less tooth removal compared to the composite of the four zirconia brands, which showed no significant difference among them. Tukey's HSD test, applied to posterior data, revealed that CC required significantly greater removal of crown structure, while EZP, KKZ, and NSZ were statistically equivalent, and SSCs required significantly less removal. CONCLUSIONS: Zirconia crowns required more tooth reduction than stainless steel crowns for primary anterior and posterior teeth. Tooth reduction for anterior zirconia crowns was equivalent among brands. For posterior teeth, reduction for three brands (EZ Pedo, Kinder Krowns, NuSmile) did not differ, while Cheng Crowns required more reduction.