NIce teeth!
I just ran across this NPR story from February, 2013. Audrey Carlsen wrote it. An excerpt:
“Hunter-gatherers had really good teeth,” says Alan Cooper, director of the Australian Centre for Ancient DNA. “[But] as soon as you get to farming populations, you see this massive change. Huge amounts of gum disease. And cavities start cropping up.”
And thousands of years later, we’re still waging, and often losing, our war against oral disease.
Our changing diets are largely to blame.
In a study published in the latest Nature Genetics, Cooper and his research team looked at calcified plaque on ancient teeth from 34 prehistoric human skeletons. What they found was that as our diets changed over time — shifting from meat, vegetables and nuts to carbohydrates and sugar — so too did the composition of bacteria in our mouths.
Not all oral bacteria are bad. In fact, many of these microbes help us by protecting against more dangerous pathogens.
That makes me wonder if antibacterial mouthwashes are a good thing for otherwise healthy people. Do they kill good bacteria, too?
Paleo Diabetic 
Stefansson also mentioned this after examining a lot of skulls. I remember him saying that their teeth were filthy and worn down but they had no cavities.
Hemming, I believe you are correct about the wearing down. Regarding filthy, I don’t know.