The white shell of enamel covering our teeth is the hardest substance in our body.
Enamel has growth rings just like trees. The growth pattern may be interrupted at any phase during the embryonic phase of tooth formation, such as an intense episode of malnutrition, emotional stress or disease, giving rise to changes in these growth rings.
Sometimes these can be so pronounced that we see them as ring-like defects around baby or adult teeth, depending on when the growth retardation occurred in early life. These defects are sometimes called “enamel hypoplasia”, and are more prone to decay.
Depending upon which teeth they are found on and which part of the tooth they are located on, we can extrapolate to the time period, within a few months, in which that interruption happened in pre-partum or post-partum life.