Three-dimensional measurement study of the maximum protuberance and cervical line of the upper molars.

The maximum protuberance and the cervical line of 48 upper first molars and 56 second molars were observed using a three-dimensional measuring device. On the basis of the results, the relationship between the maximum protuberance and the cervical line was investigated on the respective contour line and lateral aspect waveform. The contour of the cervical line was positioned at the center of the maximum protuberance in both first and second molars. The distance of the lateral aspect between the measurement points of the maximum protuberance and the cervical line were wider in the mesiodistal direction than in the buccolingual direction. In the second molar, the distance between the maximum protuberance and the cervical line was narrower, and the stricture from the tooth crown to the cervical line on the second molar was decreased. The lateral aspect waveform of the cervical line and maximum protuberance tended to be similar, but the top-to-bottom distance of undulation on the maximum protuberance was longer than that of the cervical line. The buccolingual direction of the lateral aspect waveform showed much more marked fluctuations than that of the mesiodistal direction.