Permanent tooth crown dimensions in prematurely born children

Aim. The aim was to examine the effect of preterm birth on permanent tooth crown dimensions. Materials and methods. The data consisted of 328 prematur ely born white and black children and 1804 control children who participate d in the cross-sectional study of the Collaborative Perinatal Project (USA) in the early 1960s and 1970s. The dental examinations were carried out in a standardized fashion at ages varying from 6 to 12 years in 95% of cases. Tooth crown size measurements were performed on the dental casts with an el ectronic measuring device and readout by two experienced observers accordin g to precise definitions generally quoted in the anthropological and geneti c literature. The preterm and control groups were divided by sex and race. Results. The results show both increased and decreased tooth crown dimensio ns in the prematurely born children. Significantly increased dimensions wer e found in the means df the intercuspal distances of the first permanent mo lars in the white boys and in the mesiodistal dimensions (MD) of the lower lateral incisors and the upper left first molar in the black girls. By cont rast, there were decreased intercuspal distances, MD and labiolingual (LL) tooth crown dimensions in the white girls and black boys. The statistical m ethod used was the Mann-Whitney's U-test (Willcoxon Rank-Sums test). Conclu sions. The findings partly support previous reports of decreased tooth crow n dimensions in prc term infants, but the increased dimensions found in the preterm white boys and black girls differ from earlier reports. Our result s indicate the importance of environmental factors including neonatal facto rs in determining permanent tooth crown dimensions. Growth patterns, the bu ffering capacity and the timing of sensitive moments in tooth crown volume gain may vary between the sexes and ethnic groups and the possible effect o f the accelerated growth period in preterm infants (catch-up growth) may in fluence the determination of permanent tooth crown dimensions. (C) 2001 Els evier Science Ireland Ltd. All rights reserved.