The visible portion of a tooth is referred to as its clinical crown. There's more to a tooth than what you can see, but much of its structure is subgingival (beneath the gum line). In an ideal world, your dentist would be the one to note any cavities in your teeth due to your diligence in attending regular checkups—which isn't something they'd note very often, due to your diligence with your oral hygiene. But perhaps you've not been so conscientious with your dental checkups. Still, you can typically see cavities as they form on your teeth, allowing you to take action, right? Not all cavities are so prominent.

Distal or Mesial Surfaces

Logically, an interproximal cavity develops in an interproximal space, which is the space between two teeth. These interproximal surfaces of the tooth are either the distal (facing away from the midline of the face) or the mesial (facing towards the midline of the face). Interproximal cavities aren't necessarily difficult to treat, and this treatment is a standard aspect of general dentistry. These cavities are, however, difficult to spot. 

Dark Spaces Between Your Teeth

An interproximal cavity can make the dark spaces between your teeth appear to be even darker. This is in fact a visual trick; you're not seeing the space between your teeth, but a darkening patch of distal or mesial enamel. This will become more conspicuous as the cavity worsens. 

Signs of a Cavity

A worsening interproximal cavity will create the same symptoms as a standard cavity. The tooth will become increasingly sensitive as the deteriorated enamel has allowed the tooth's nerve to be corrupted by bacteria. The irritated nerve will also be more susceptible to the temperatures of food and drink, creating toothache. These symptoms may have been averted with flossing or another form of interproximal cleaning.

Flossing Your Teeth

If you're only an occasional flosser, this could be another way in which you notice an interproximal cavity prior to any physical symptoms. The corroding tooth enamel will create a small indentation, and your dental floss may become snagged.

Prompt Repairs

Your interproximal cavity should be repaired without delay. These cavities are filled in the same manner as a standard cavity—with an emphasis on restoring the tooth's functions, preventing further degradation of the enamel. The aesthetics of the restoration are also important, meaning tooth-colored resin will be used. 

For more information on general dentistry, contact a professional near you.