Cusp height relationships between the upper and lower molars in Japanese subjects.

Relationships of cusp height between the upper and lower first molars and between the deciduous second molars in Japanese subjects were analyzed with the aid of moiré contourography. In permanent molars, the height of the hypoconid had a mean value similar to that of the upper trigonal cusps, indicating that upper and lower functional cusps of the same height occlude with each other. In deciduous second molars, however, hypoconid heights were significantly smaller than trigonal cusp heights. Such differences in cusp height between permanent and deciduous dentition may be related to the function and phylogeny of tooth or jaw movements.