Teeth have an outer layer called enamel, which is mainly mainly made up of calcium, which is itself white in colour. However, enamel can vary in colour from yellowish to grayish. They’re also translucent, which means they allow light to pass through them. That means that the colour of your teeth is not just dependent on the colour of the enamel, but also of the inner parts of the teeth made of something called ‘dentin’. Generally, they’re white, because they reflect all parts of the colour spectrum equally, which is how white light occurs!