In this series we are going to go from the chewing surface of a tooth down into the cells that make a tooth, and see what goes wrong without enough fluoride. (These drawings are just a model to try to understand how it works.)

This image shows the chewing surface of a simplified tooth. Point A is the top of one of the ridges of a tooth (called cusps), and the lines in the center near point B are the valleys (called sulci). The general problem with a lack of fluoride is that sometimes the valleys are too deep. This is called "pits and fissures". A fissure is a hairline crack at the bottom of the valley. These fissures often go deep into the tooth, all the way through the enamel (the hard outer covering of a tooth). If 2 fissures cross, like at point B, often a pit will be formed. A pit is more like a hole, and is usually a little bigger. The pit and fissure area is obviously the site of much tooth decay. The modern technique is to seal this with plastic resin. The better technique, if you can start in pregnancy, is to take fluoride as these teeth are forming, which will prevent 100% of pits and fissures.

Ripples