Scanning electron microscopy of the neonatal line in human enamel

Neonatal lines in deciduous and permanent teeth showed changes in direction of the prisms and in their widths, confirming the findings of others. Structural changes in the prisms consisted of a well-defined line crossing the prisms at the prenatal side of the neonatal line and a wider diffuse zone of reduced crystal density at the postnatal side. It is suggested that these represent disturbances in physiological activity at birth and the succeeding 3 to 4 day period.