Make an Impression
We’ve all heard of people being identified "by their dental records”. Here's a chance to play forensic dentist, and find out how the technique works.
>>> You will need:
- Scissors
- Styrofoam plate (don’t use general packaging as it needs to be sterile enough to put in your mouth)
- Pen
- Note-book, paper or a computer
- Dentist-style white coat for dressing up (optional)
Safety first! Be sure to read the safety note at the bottom of this page.
>>> What to do:
1) Cut the styrofoam into mouth-sized pieces. You’ll need two per impression.
2) Put two of the styrofoam pieces together and bite down on them as hard as you can.
3) Label the pieces “top set” and “bottom set” (take them out your mouth first!).
4) Now put your dentist coat on (metaphorically or otherwise!) and study the impressions.
5) Start by counting the number of teeth on the top and bottom, the size and shape of the jaw-line. You should also look for funny shapes, chips, broken teeth, etc.
6) Keep a record of your notes, you can also add any useful information you might not know from the impression itself (i.e. fillings).
7) This can be turned into a puzzle with a group of friends. Get everyone to make a dental impression and take notes. Then mix them up, and see if you can match the imprint to the actual teeth - just from the information you wrote down.
>>> Why this works:
We all know how useful fingerprints are for identifying people, but not that many have their fingerprints on record. However, nearly all of us have medical records which have useful identifying information such as height, weight etc and whether we’ve broken bones or had an operation.
Dental records are particularly useful to forensic scientists, because teeth are one of the hardest substances in the body. This means they tend to look the same throughout a person's life. (Unless you break one that is - but then that should be on your dental records too…)
SAFTY FIRST! This activity uses polystyrene. Be careful of any fragments, especially around young children.
Polystyrene can be squashed to be quite small but then re-expands once inside the body to cause serious blockage. Further, it does not show up on x-rays, which makes it very hard to detect if you do have to seek medical treatment.