An examination of dental crowding and its relationship to tooth size and arch dimension.

This investigation was undertaken to examine the extent to which tooth size and jaw size each contribute to dental crowding. Two groups of dental casts were selected on the basis of dental crowding. One group, consisting of 50 pairs of dental casts (18 males and 32 females), exhibited gross dental crowding. A second group, consisting of 54 pairs of dental casts (24 males and 30 females), exhibited little or no crowding. Means and standard deviations of the following parameters were used to compare the two groups: individual and collective mesiodistal tooth diameters, dental arch perimeters, and buccal and lingual dental arch widths. Statistically, the crowded and noncrowded groups could not be distinguished from each other on the basis of mesiodistal tooth diameters. However, significant differences were observed between the dental arch dimensions of the two groups. The crowded group was found to have smaller dental arch dimensions than the noncrowded group. The results of this study suggest that consideration be given to those treatment techniques which increase dental arch length rather than reduce tooth mass.