Another example is extreme dental dysplasia ~ particularly when it's associated with missing teeth (that just never came in).
Turning your premolars sideways gives you an extra cutting edge for eating lots of raw meat ~ losing those teeth lets them turn easily, and also frees up some space so all your others can turn their best edge the most advantageous way.
The Sa'ami, who've been living all the way up to the Arctic for the last 14,000 years have an 18% incidence of the situation where teeth just don't come in.
That’s interesting about the missing teeth. I, on the other hand, have a son who had 6 wisdom teeth. When we went to get them pulled they wanted to know if he had any Eskimo blood. His father had a great grandmother who was Canadian Cree Indian. I suppose the Crees could have wandered far enough north to encounter some Eskimos.