Maternal smoking and tooth formation in the foetus. III. Thin mandibular incisors and delayed motor development at 1 year of age.

Dental casts from 2159 black and white Americans with detailed neurological data available from the Collaborative Perinatal Study were examined to investigate the relationship of maternal smoking during pregnancy and delayed motor development at 1 year of age to morphological traits in the dentition. Earlier results have indicated that maternal smoking during pregnancy may cause selected tooth size metric reductions in the deciduous dentition and at least in some of the permanent teeth with prenatal crown formation, these features being influenced by sex and race differences. The present results suggest that a thinning of the incisal parts of the permanent mandibular incisors is associated with heavy maternal smoking during pregnancy, and those white girls, in whom this dental variant is found, have probably experienced more severe central damage during the smoking sensitive gestational months, as is also seen in a delayed motor development at the age of 1 year.