Detecting tooth decay today has changed remarkably from the process just a few years ago. As little as 20 years ago it was the standard to find cavities by seeing the enamel (the outer layer of the tooth) broken down, or by finding a "sticky" spot in the enamel with a dental explorer. Today, however, the increasing use of fluoride has made the enamel so hard that these older, time tested methods don't always work.
A Short Dental Anatomy Lesson
The enamel of a tooth is the hardest substance in the body...much harder than bone. A major part of the enamel is a material called "hydroxyappetite", which can be dissolved by acids that dental plaque produces thus causing dental decay (cavities). Fluoride works by combining with the "hydroxyappetite" to form "fluoroappetite", which is much more resistant to this acid. However, if the enamel does not completely form in the grooves of the chewing surfaces of the teeth, then this acid can get to the dentin layer of the tooth (underneath the enamel). Unfortunately, fluoride does not protect the dentin. So the problem is that since the enamel still is essentially intact, and the dentin has decay, this decay is very difficult to detect using the old methods.
Modern Technology to the Rescue!
A new instrument that we now have in our office helps to combat this problem. Called the "Diagnodent", it is a device that sends a harmless laser beam (like the scanner at the supermarket) into the biting groove of the tooth. Decay reflects this beam differently that healthy tooth structure, so if decay is present, we can measure the spot and extent of the decay even though the enamel appears healthy! In this way we can restore teeth early in the decay process thus preventing large fillings and weakening of the tooth.