Ever wondered what the point is in having teeth that fall out only to be replaced with a whole other set?
I have been writing a story about the tooth-fairy, and so this question recently reared its head. And it turns out that baby teeth aren’t just a random part of growing up, they are there for a purpose.
Fill in the gap
The purpose for baby teeth is…. for kids to be able to eat solid food.
Okay, so maybe you had guessed that much of the answer, but wait and I’ll explain further.
Before the age of about four to six, a child’s jaw is simply too small to accommodate the full grown set of adult teeth. Baby teeth fill in that gap before adult teeth erupt, giving kids something to chew with before they are big enough.
Guides
But baby teeth do more than allow kids to chew down some nosh. They are important in preparing the way for adult teeth to move into town. Baby teeth positioning is thought to guide adult teeth into position, helping proper spacing in the adult jaw.
I’m not sure my baby teeth did a good job, as I had to have several sets of braces to persuade my adult teeth into the right place 😦
Well rooted
If you have had an adult tooth removed you will know that they have large roots. But when baby teeth fall out they don’t have any, why not?
Turns out that baby teeth do have roots! But why don’t we see them when they come out?
When the child’s jaw reaches its mature size, the new adult teeth begin to move up into place. This pressure is thought to cause the root of the baby tooth to disintegrate and be re-absorbed into the gum….a pretty strange idea.
The loss of root leads to the baby tooth becoming loose, and with pressure applied by the adult tooth pushing from bellow, the rootless tooth is eventually released from its gummy habitation.
Fall
Teeth like a bit of order and the rough rule is that the first baby tooth in is the first one that falls out. This usually looks like the lower incisors followed by the top front two, and in my experience those always fall out just before school photos.
However, there are cases when baby teeth aren’t released as normal. Sometimes it’s because the adult tooth is not emerging in the correct place and therefore not applying the pressure required to disintegrate the baby tooth root. But there are a range of other reasons, meaning it is fairly common for some baby teeth to be removed by a dentist in order to encourage the adult teeth to erupt in the correct position.
But once they are in, the adult teeth are permanent fixtures and important to take care of…says I who had to have six fillings last week 
P.S. Mammoths had several sets of teeth, six in total, that came through at different stages of their lives as their jaws become large enough to accommodate the next set of pearly whites.
Science FYI 