Science Questions

Where do the roots on baby teeth go?

Sun, 22nd Jun 2008

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Question

Geoff, Australia asked:

I have two young daughters aged 6 and 8. Theyíre losing their baby teeth. Iím wondering why the teeth falling out donít have any roots. Surely teeth have roots. Where are they going?

Answer

Baby teeth definitely do have roots and I have a painful personal experience to recount on this front.  When I was about 14 my dentist decided that I had too many of my milk teeth left and decided they needed pulling out.  He pulled them out and it was terrifically painful because they all had very long roots.  The ones that had fallen out didnít have any roots.

The reason is that when you have secondary dentition, or adult teeth, they come up underneath where your baby teeth are and they erode the root away so this loosens the tooth and makes it fall out.  Only once thereís a secondary tooth to come in its place because evolutionarily speaking it wouldnít do to have a period with no teeth.  If all your teeth just fall out then youíd have nothing to replace them with.  You might starve if you were back in ancient history and didnít have the welfare start to look after you with pot noodles.  Thatís why you have this dissolving of the root in order that the tooth can be replaced by secondary dentition.  What heís seeing is nature in action.

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Geoff asked the Naked Scientists: I have two young daughters, aged 6 and 8, who are in the process of losing their baby teeth. I'm just wondering why the teeth that fall out have no roots, like the ones you see on teeth that are knocked out or removed. Do the adult teeth moving up from below gradually destroy the baby teeth's roots and is this why they fall out? Thanks. What do you think? Refractor, Thu, 12th Jun 2008

Hi Geoff

Welcome to the forum!

This is an excellent question. The reason why baby or "deciduous" teeth appear to be rootless is because the root resorbs (is dissolved) as the secondary tooth grows up beneath it. This has the effect of loosening the tooth so that it falls out more easily, but only when there will soon be a permanent secondary tooth to replace it.

In this way a child is never left toothless, which in the "wild" might have had consequences for an individual's ability to feed themselves.

I can also confirm from painful personal experience that deciduous (milk) teeth definitely do have roots, because I still had quite a few primary teeth (chiefly molars) even when I was 14, and my dentist insisted on pulling a load of them out. The lack of any adult teeth ready to take their place meant that the extraction was painful, but not half as painful as having to eat with nothing but my incisors for 6 months!

Chris chris, Thu, 12th Jun 2008

Very good questions.. I always wondered about that..Thanks Chris and thanks for the podcast Link! Karen W., Tue, 29th Jul 2008

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