Fluctuating dental asymmetry: a measure of developmental instability in Down syndrome.

Subjects with Down syndrome provide a useful model for investigating the effect of chromosomal aneuploidy on developmental pathways. Studies suggest that a major effect of trisomy is a decrease in developmental stability. The present study examines fluctuating dental asymmetry in Down syndrome. Mesiodistal crown diameters were measured from dental casts of 114 Down syndrome subjects. Correlation coefficients for antimeric permanent teeth served as an index of dental asymmetry. These values were compared with normal values obtained from the literature. Fluctuating dental asymmetry is thought to reflect the relative success of developmental homeostasis in countering developmental disturbances. Down syndrome subjects have significantly increased dental asymmetry. In addition, they show a disproportionate increase in dental asymmetry for those teeth reported to have the least developmental stability. These results support the contention that the chromosomal imbalance in Down syndrome results in amplified developmental instability.