Although any tooth surface is susceptible to decay, the most vulnerable spots are the uneven or hard-to-reach areas where bacteria can take refuge. Particularly prone to decay are the crevices (known as pits and fissures) on the surface of the crown, the points where adjacent teeth meet, and the exposed neck of the tooth at the gum line. Root decay is a growing problem, particularly among people older than age 55 whose gums have receded as a result of periodontal disease.
Your dentist can often spot decay on the visible surfaces of the teeth, while cavities in unseen spots—such as in the pits and fissures or between teeth—generally show up as dark areas on X-rays. A traditional method of uncovering decay by probing for soft spots in the teeth with a sharp metal tool has fallen out of favor. Researchers began to suspect that this practice actually augmented the decay process by piercing areas of soft enamel and spreading bacteria from one tooth to another.
Still, finding cavities can be tricky. One of the biggest challenges facing the dental community is accurate detection of the more subtle manifestations of decay, including root cavities, active cavities under existing fillings, and areas of demineralization (known as incipient caries). To this end, researchers are testing several technologies. Some promising avenues include using fiber-optic light to visualize deep decay between teeth and using electrical current or laser energy to identify reductions in tooth density that signal demineralization.
Source: Dental Health for Adults: A Guide to Protecting Your Teeth and Gums. Copyright © by Harvard University. All rights reserved.