Tooth crown size in human females with 45,X/46,XX chromosomes.

Permanent tooth sizes in 15 Finnish females with a 45,X/46,XX chromosome constitution were measured and compared with those of normal females, first-degree female relatives and 45,X females. Mesiodistal crown diameters of the 45,X/46,XX mosaic females were smaller than those of normal females but similar to those of females with pure 45,X chromosome constitution. Labiolingual crown diameters of the 45,X/46,XX mosaics were near normal, being consistently larger than those of 45,X females. The mesiodistal crown sizes are consistent with a decrease in enamel thickness in 45,X/46,XX mosaic females. The difference in labiolingual dimension between teeth of 45,X/46,XX mosaic females and 45,X females may relate to a gradual normalization of growth when normal 46,XX cells are mixed with defective 45,X cells.