Harris Edward F, Clark Larkin L
Department of Orthodontics, University of Tennessee, Memphis, TN 38163, USA.
Angle Orthod. 2008 May;78(3):460-5. doi: 10.2319/022807-104.1.
To test the null hypothesis that American blacks do not have a higher frequency of extra permanent teeth than whites.
Panoramic radiographs of adolescent orthodontic patients, either American whites (n = 1100) or American blacks (n = 600), were reviewed systematically.
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.
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.
检验美国黑人额外恒牙的发生率并不高于白人这一零假设。
系统回顾了美国白人（n = 1100）或美国黑人（n = 600）青少年正畸患者的全景X线片。
额外切牙、前磨牙和磨牙的发生率在黑人中均显著更高。在白人中额外切牙是最常见的额外牙齿（额外磨牙最不常见），而在黑人中情况正好相反。总体而言，优势比为8.8（95%置信区间 = 3.9, 20.0），证实美国黑人拥有额外恒牙的可能性显著高于美国白人（几乎高9倍）。
该假设被拒绝。黑人与白人额外恒牙的发生率和模式均存在显著差异，表明导致多生牙的发育机制中相关（但未明确）因素的发生率不同。
