Slicing and Dicing

This morning, I drove to RTP to meet with a dentist who is doing research into some specific protein in teeth that perhaps mixes with calcium and... yeah, honestly, his interests were far too complicated for me to really understand. There was a lot of technical, elemental explanation going on. He has been collaborating, however, with the geochemist at UNC in trying to figure out if dentine from different areas of a tooth provide different strontium signatures. If they do, it is theoretically possible to track one person's movement throughout his or her adolescence - on a scale of months rather than years or decades. So he seemed interested in my project and was actually impressed by my box full of 2,000-year-old teeth. (No one else ever is.)

The process of sawing them into thirds was actually fairly simple. He "glued" the tooth to an acrylic pad using simple heated wax. The pad with attached tooth was then positioned above the saw blade, which spun through water to help lubricate its path through the tooth, and then sliced it in two. He moved the saw blade about 3 mm and made a second cut. The tooth, still attached to the wax, was cut into three pieces. The idea, I guess, is to extract both the enamel and the dentine from an area as close as possible to the dento-enamel junction - about 100 microns from this junction in either direction. The closer the enamel is to the DEJ, the earlier in a person's life it was formed. So the idea is to take a sample of enamel very close to the DEJ while not getting any dentine contamination. This is the middle section of a lower left first molar that he sectioned for me. There isn't a lot of enamel left, as you can see indicated by the red line. This individual (from Castellaccio, which had more dental wear than Casal Bertone) had worn his teeth down, even though he was under 20 years old. But there's a lot of dentine to choose from, which is good.

As I noted a few days ago, I was worried that needing enamel from near the DEJ would eliminate some of the children from my study. While it does eliminate very young children (infants whose cusps are just forming), we sectioned the first molar of a child who was around 3-4 years old when he or she died, and there was plenty of dentine. So teeth that I extracted from the crypt (our word for a tooth socket in an archaeological sample devoid of flesh) will likely produce some very good samples of both enamel and dentine. Yay! This is the tooth that the dentist sectioned for me - note the abundance of enamel and clearly demarcated dentine. There's also some sort of organic matter (possibly root material, or possibly mummified/petrified tissue), which is the brown lump in the lower right.

I'm all set up to saw teeth into thirds now, but I'll need to go to the geochem lab tomorrow or Wednesday to learn how to use the drill that will extract the enamel and dentine. And then learn how to prepare those samples for SEM. Yeesh.

The weirdest thing was when the dentist asked me if I wanted to take any precautions against disease when cutting the teeth. I asked what he meant by that, and he said that diseases like hepatitis can survive for a long time in organic material like dentine - and he doesn't want me getting hep-B from ancient Romans. It would be pretty hilarious to explain to Student Health that I got a communicable disease from Oldeus Diseaseus, but I honestly don't think I'm at any kind of risk for catching anything. If I survived plowing through the Casal Bertone skeletons that were covered in rat droppings and cat urine, I doubt that teeth will hurt me. Will they?


Heather said…
1. Nerd Woman is utterly fascinated.

2. Use precautions. =)

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