Small primary tooth-crown size in low birthweight children.

As part of a longitudinal study of dental development in a group of low birthweight children (LBW), study models of 72 children at age 7 years were measured to determine the tooth-crown size of primary molars and canines and to compare the findings with equivalent measurements in 60 normal birthweight (NBW) controls. Mesiodistal (length) and buccolingual (width) dimensions were measured manually, using dial calipers. Primary canines and molars were smaller in the LBW than the controls, with significance values ranging from P < 0.001 for the mesiodistal dimension of maxillary and mandibular canine (> 4% difference) to a non-significant difference P < 0.2 for the buccolingual dimension mandibular first primary molar (1.8% difference). Within the LBW group there was a positive correlation between birthweight and mesiodistal tooth size. Small primary tooth size in LBW children may be influenced by both genetic and environmental factors. The shorter prenatal growth period and poor perinatal and early postnatal development may influence the developing deciduous dentition. Small primary tooth-crown size, associated with LBW, should be considered in all population studies of tooth size.