Third molar (M3) development determined from dental radiographs in American blacks (African Americans; n=637) aged 14-24 years was contrasted against American whites (n=563) from a previous study using the method of Demirjian et al. Differences were assessed using descriptive statistics and the parametric proportional hazards model. For each developmental stage, the probability of an individual being at least 18 years old was evaluated. As in other M3 studies, there were highly significant modal differences, but the age ranges at each stage overlapped considerably. Black-white differences were highly significant with developmental stages occurring in blacks a year or so earlier. Gender differences also varied significantly, both with increasing age and between races. The empirical likelihood that an African American male with fully developed M3's is at least 18 years old is 93% and that for African American female is 84%. Corresponding risks for whites are 90% and 93%.

The intertwined effects of normal aging processes and time-progressive diseases produce systematic changes in many oral and dental tissues. This cross-sectional study of pulp dimensions and root lengths in sound teeth tested for changes with age in adulthood while controlling for differences in gender and race (black, white). Age was the paramount determinant of pulp size which decreases via the accumulation of secondary dentin. In some instances the rate of change increases in older adults with an inflection point at 35-40 years of age. In contrast, root lengths are statistically independent of age once gender (male greater than female) and race (black greater than white) are controlled. Causes of the lack of association with age are discussed.

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