SEM Survey of Human, Shark, and Rodent Teeth

James Yuzawa
University of Rochester, Department of Computer Science
Rochester, NY 14627 -

Rodent Teeth


This sample was obtained from a skull believed to be a raccoon. This skull was quite old and sitting on a shelf for more than two decades.

This sample was obtained from a dead rodent believed to be a woodchuck. The sample as a whole was a piece of jawbone. There was visible tooth decay on the surface of the tooth.

Raccoon

Figure 14: False-color image from BSE (orange), SE2 (yellow), and InLens (red) detectors. View of edge of fracture near enamel surface.
Figure 15: Image of same fracture from Figure 14. Tooth is made of spongy dentin surrounded by thin layer of enamel less than 100 microns thick. Hollow inner part of root devoid of pulp tissue is visible at bottom.

Woodchuck

Figure 16: SE2 detector. Frontal cross section view of polished dentin and dentin-pulp interface. Pulp has decayed away, but the interface still exists. The dentin tubules appear to connect with the pulp (not pictured, since decayed).
Figure 17: BSE detector. Cross section showing dentin (top left), enamel, and stratified dental calculus deposits (bottom right). Thermoplastic is material in bottom right corner. Tooth decay has accumulated in layers on the surface and started to eat away at the enamel surface.

Woodchuck Dentin

Figure 18: SE2 detector. View of dentin in cross section. Dentin tubules illuminated by edge effects. Density of tubules is greater near the enamel. Enamel lacks tubules.
Figure 19: Image analysis done in ImageJ on part of Figure 18. Threshold was able to discern tubules from halos of edge effects.

The ImageJ data found 1310 particles within the spongy dentin. The average area was 1.089 μm2 with a standard deviation of 1.372. The average Feret diameter of a hole was 1.481 μm with a standard deviation of 0.930.

Composition

Figure 20: The EDS results for the raccoon tooth. Calcium, phosphorus, carbon, and oxygen are all present as expected.