We investigated whether there is a correlation between the buccolingual crown diameter and cusp tip distance and if that can be considered a factor influencing the formation of a transversal malocclusion. The buccolingual crown diameters and cusp tip distances of all premolars and first molars of 102 normal dentitions and 123 dentitions with a transverse malocclusion were measured and examined for significant differences. We also investigated whether there were differences in size between the genders and between left and right sides. General differences in buccolingual crown diameters ranged from 0.3 mm to 0.6 mm, and in cusp tip distance from 0.4 mm to 0.7 mm. Buccolingual crown width was generally greater in boys than girls, whereas we observed no statistically significant difference in cusp tip distances. Comparison of left and right sides revealed no significant difference. We were able to statistically prove the correlation between buccolingual tooth diameter and cusp tip distance. The results suggest that larger teeth with a greater cusp tip distance offer a more favorable prerequisite for the appearance of regular transversal occlusal relations than those with a smaller distance. The buccolingual crown width and its corresponding cusp tip distance seem important for initial contact with the antagonists, and may be regarded as a factor that determines whether or not a crossbite develops.