Last month we looked at teeth under the microscope. This time we will look at a some tooth brushes that help keep them clean and healthy. One is a brand new brush, the other is old, and has been used for a long time.
The tooth brush with the orange handle is the new one, the white-handled one is the old one. It is easy to see some basic differences between the two. The new one still has the bristles nicely arranged in straight bunches. On the right you can see the ragged, splayed out bristles of the old, worn out tooth brush. You can also see some differences in design of the arrangement of the bunches of bristles.
At higher magnifications we can see that the old bristles are spread out, so that they each act on their own, rather that working with the rest of the bristles in the bunch. This may be less effective at removing deposits from the teeth.
Other effects can be seen in the scanning electron microscope images below where the shape of the bristle ends can be seen. The new bristle (on the left) is cut straight across at the end, giving a sharp edge to dislodge built up deposit from a tooth. The worn bristle (middle image) is more rounded and will more easily slide over the teeth without dislodging food particles. At higher magnification (on the right) we can see that the bristle is not clean like the new bristle, but coated with dried on tooth paste, and may harbor bacteria which will not help to keep our teeth clean.
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Last Update: 4/15/98