Caries is an infectious disease caused by bacteria that live in the mouth and corrode the hard tissues of the tooth (enamel and dentin).
An advanced caries is rather easy to diagnose with a simple visual examination, as it appears as an eroded cavity with a basically brownish and softened bottom. This "crater" is the result of a carious lesion begun long before, starting from a so-called white-spot (small opaque spot present on the tooth enamel, indicative of demineralization still reversible). The white spots are therefore the first stage of the carious lesion: if they are not identified and treated in time the demineralization process that originated them continues giving rise to a cavitary lesion.
For an experienced dentist it is easy enough to recognize a cavity or a white spot on visual examination, but only if these are placed on visible dental surfaces. The dentists have in fact available lights and magnifying means suitable for the purpose, in addition to very thin probes (specillo) to understand if the lesion contains decalcified and soft tissue.
On the other hand, it is much more difficult to notice the so-called interproximal lesions, ie those lesions that form between one tooth and another. Equally difficult is the diagnosis of caries developed below crowns or pre-existing restorations or under a microscopically intact enamel. In all these cases, limiting the diagnosis to a visual examination alone, 50-80% of carious lesions escape control; unfortunately, the undiagnosed lesions are destined to evolve in a silent way only to be diagnosed only when the loss of substance will be important and their presence evident.
For all these reasons, on visual examination it is necessary to associate a radiographic survey or even more sophisticated and advanced techniques, such as:
- transillumination: it is based on the principle that altered dental tissues can be traversed by light in a different way than healthy ones, showing themselves as well visible dark spots; this technique is particularly suitable for the interproximal areas of the anterior teeth;
- electrical conductance: it is based on the principle that altered dental tissues, being demineralized in fact, conduct electric current differently; it is particularly suitable for the diagnosis of caries of hidden occlusal surfaces (that is, occlusal caries already penetrated in dentin that form under a microscopically intact enamel);
- laser fluorescence: the principle is similar to that of transillumination, but a laser diode is used as a light source; also in this case, laser fluorescence is very useful for the diagnosis of hidden occlusal caries.
