July 17, 2007

Back and Better than Ever!

OK, so probably not. But here's another Pathology Tuesday for those of you who like this kind of stuff. I was telling Patrick that one of my Italian colleagues is doing research on extramasticatory wear for her thesis. Lest this term get bandied about in my house as a catch-all crazy anthropology word (much like I throw around "algorithm" whenever I want to point out how dorky and jargon-laden Patrick's world is), today's episode is about extramasticatory wear.

Teeth are, as you all know, quite resilient. Enamel is among the hardest materials in the human body, resulting in often excellent preservation of teeth, even 2000 years later. Teeth don't regenerate during your life, which means forensic experts can use your individual dental morphology to identify you, particularly if you have dental work (like filling a cavity) done. Many of your teeth are formed in utero, making them a little time capsule that can reveal to an isotope chemist your diet and disease load as a child, whether or not you moved to a different place while you were growing up, and even the age at which you were weaned! Teeth are, of course, functional as well. They allow us to chew (or masticate) our food, but like our primate ancestors we can also use them as weapons and as tools. Use of the teeth as tools generally results in odd patterns of wear and chipping and can contribute to gum disease and cavities as well. For the most part, when an anthropologist identifies extramasticatory use of the teeth it is through odd dental wear patterns in a population. People's teeth wear differently depending on their bite - overbites are common to people of European ancestry and edge-to-edge bites to people of Asian ancestry - and other issues like whether or not they grind their teeth at night and what kind of food they eat. Extramasticatory wear, however, is immediately recognizable and most often involves the anterior teeth (the front teeth and canines).

Below is a video of a mandible that I found yesterday with anterior extramasticatory wear. Watch as I spin the mandible around and look for the following... On the left, a missing second molar, a first molar with two abscesses at the roots (small holes in the bone) and a giant cavity, wear on the anterior teeth angled at about 45 degrees with nearly complete loss of the crowns of the teeth, and an abscess under one of the front teeth. On the right, more strange anterior wear and an impacted wisdom tooth (you can see it poking out of the bone, but it never erupted and would have been covered by gum tissue during life).



I don't know what this person was doing with his teeth, but anthropological reports from other regions of the world indicate perhaps he was running something through his teeth by gripping it in his mouth and pulling it out and down. This was a method of working leather in some ancient societies, so it is possible that this Roman engaged in a similar practice.

1 comments:

Anonymous said...

For a second there, I thought "extramasticatory wear" meant bras and the like, as in outside + breasts + apparel. Good laugh!

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