1998 Volume 18 Issue 2 Pages 206-213
The reduction of the second maxillary molar of Chinese was analyzed from a metrical perspective. Materials used were plaster casts obtained from 100 male Chinese living in Jinan (Shandong province). Dimensions of the crown were measured with a digital caliper (0.01 mm). The dimensions of the crown included mesiodistal and buccolingual crown diameters, the distances to the direction of the diagonal line, the cusp sizes, and intercusp distances. The molar size sequences and reduction indices were calculated in order to compare first and second molars (Ml, M2). Ml was larger in the mesiodistal diameter (P<0.01). M2 had slightly larger buccolingual diameter than Ml did, but the difference between them was not significant. The diagonal sizes were significantly larger in Ml than in M2 (P<0.01). The intercusp distances were also significantly larger in Ml (P<0.01). The distal two cusps were more developed in M1 than in M2, while the mesial two cusps were nearly the same sizes in Ml and M2. M2 was more variable in size, with the exception of the intercusp distances. Linear discriminant function analysis was performed for the crown dimensions in order to investigate the difference between M1 and M2. The hypocone size and buccolingual diameter was the most effective measurements for the discrimination between Ml and M2. The paracone which was formed early in the developmental stage, hardly contributed to the discrimination.
