How Teeth Are Like Trees

I was at my dentist the other day, and he spent the whole time using analogies to explain things to me.  He began by asking me if I was really sick when I was about 4 years old.  I was a little confused, but he pointed out that I have a white spot on the back of one of my teeth.  He said that teeth are like trees and like the rings in trees you can learn things from your teeth and date them.  Apparently, that spot would indicate high antibiotic use or malnutrition right during the period of development.

He later went on to explain the surface of the teeth and how a round object that hits the ground is less likely to break than a square object.  He was talking about how the tops of teeth get ground down over time and the risk that it creates to the stability of the tooth.