Interaction between Relative Molar Size and Relative Number of Cusps

M1>M2 ........... 2 M2>Ml orM2=M1. 0 imber of cusps have been in whom the mesiodistal crown diameter of the manjiables in both sexes and dibular first molar exceeded that of the mandibular ions (A. A. DAHLBERG, second molar, the number of cusps on Ml exceed61; S. M. GARN, A. A. ed the number of cusps on M2 in 86 individuals and R. S. KEREWSKY, (79 per cent). Only 23 of these subjects, or 21 per 6; S. M. GARN, A. A. cent, were characterized by an equal number of and R. S. KEREWSKY, cusps on both mandibular molars. However, in 13 night therefore postulate additional subjects, in whom the second molar ive crown size of the first equaled or exceeded the first molar in crown size, relative number of cusps the relative number of cusps was reversed; four subjects had more cusps on the first molar than on the Ls of European ancestry second, and nine (69 per cent) had an equal number of cusps on the two molars. This difference in cusp part by USPHS grant DEnumber was significant by stochastic x2 test both for tute of Dental Research, Nathe number of sides that could be studied (N = 224, B. Lewis and morphological X2 = 52.2) and for the total number of subjects (N = 122, x2 = 15.6). The degree of association beable on request to the authors. tween relative molar size and relative cusp num-