Methods: The research was carried out on eighteen upper deciduous canine from normal (7), CP (7) and DS (4) children. The teeth were bisected into two equal halves. A thin ground section (100-150 micron) was prepared from each tooth. The total enamel width and the prenatal enamel width were measured one millimeter from the DEJ in the cusp tip. The ratio of prenatal to total enamel width was used in order to compare between the groups.
Results: Total enamel width was least in CP teeth, followed by the controls and was greatest in DS teeth. In the controls the ratio of prenatal to total enamel width showed little variation and was 0.37 (0.29-0.45). In CP teeth the ratio was 0.43 (0.25-0.67). On the other hand, in DS teeth the ratio was highest with a mean value of 0.56 (0.44-0.67). This increase in the ratio of prenatal to total enamel width emphasizes acceleration in prenatal canine enamel growth in DS group.
Conclusion: Our results indicate that prenatal development, expressed in enamel apposition, is slower in CP children, whereas it is accelerated in DS children. The findings for the CP canines are echoed in the later developing primary teeth. On the other hand, the later developing primary teeth of DS children show a growth lag in contrast to the accelerated growth found in the canine. These results for changing growth rates throughout development of primary teeth in DS conform to those described prenatal skeletal changes on the basis of ultrasound examination.