An interproximal cavity is tooth decay that forms on the surface where two teeth touch. These cavities are often called “hidden troublemakers” because they are not visible during a standard self-inspection. Decay begins when plaque bacteria feed on sugars, producing acid that erodes the enamel in this tight space. Interproximal cavities are a common dental issue that can progress significantly before causing noticeable problems. Professional examination is necessary to confirm the diagnosis and prevent the decay from advancing.
Symptoms You Can Identify
While the decay itself is hidden, an interproximal cavity may cause several noticeable symptoms. A common sign is increased tooth sensitivity, particularly to temperature extremes like hot or cold drinks, or when consuming sweet foods. This sensitivity often indicates that the decay has progressed beyond the outer enamel layer and reached the underlying dentin.
Pain or a dull ache when chewing or biting down is another indicator, especially when pressure is applied to the affected tooth. You might also notice that dental floss consistently shreds, frays, or catches in a specific spot between two teeth. This snagging is a physical sign that the enamel surface has begun to break down, creating a rough edge.
A persistent bad taste or unusual odor that does not go away with brushing can also be associated with the area. This may signal that food debris is chronically trapped in the developing decay, allowing bacteria to thrive. If food regularly gets wedged in the same spot, it can be an early hint of an evolving problem.
Why These Cavities Are Difficult to See
Interproximal cavities are challenging to spot due to their anatomical location. The decay begins right below the contact point, which is the tight area where two adjacent teeth meet. This contact point acts as a shield, completely hiding the early stages of decay from direct visual inspection by both the patient and the dentist.
The enamel covers the tooth and must be penetrated before the decay becomes visible. By the time the decay has eroded enough tooth structure to create a visible hole or dark spot, it has often already progressed significantly. The surrounding tooth material effectively masks the lesion until it is advanced, often reaching the inner dentin layer.
How Dentists Confirm the Diagnosis
Accurate diagnosis of interproximal decay relies heavily on professional tools and techniques that can see through the tooth structure. The gold standard for detecting these hidden cavities is the use of Bitewing X-rays. This specific radiograph captures the crowns of the back teeth in the upper and lower jaws, providing a clear, side-by-side view of the interproximal spaces with minimal overlap.
On a Bitewing X-ray, decay appears as a dark or radiolucent area in the enamel or dentin. This allows the dentist to visualize the lesion’s depth and size long before it is clinically visible. Without these images, decay can remain undetected until it is deep enough to require more extensive treatment.
Dentists also use other diagnostic aids, although they are secondary to X-rays. A dental explorer, or probe, may check for roughness or softness near the contact point, but this is less reliable for early lesions. Some offices use transillumination or laser fluorescence devices, which shine light onto the tooth. Changes in light reflection can indicate early mineral loss, but a definitive diagnosis requires a combination of a thorough clinical exam and Bitewing X-rays.
Treatment Options for Interproximal Decay
The treatment pathway is determined by the extent and severity of the confirmed decay. If the cavity is caught very early, while still superficial and contained in the outer half of the enamel, the dentist may recommend a non-invasive approach like recalcification. This involves applying a high concentration fluoride gel or varnish to encourage the enamel to remineralize and repair itself.
For the majority of interproximal cavities that have penetrated deeper into the enamel or reached the dentin, a dental filling is the standard treatment. This procedure involves removing the decayed tooth structure and restoring the tooth to its normal shape and function using materials like composite resin or amalgam. If the decay is extensive, but the pulp is not infected, the dentist might opt for an inlay or onlay, which is a restoration fabricated outside the mouth and then cemented into place.
If the decay was left untreated and has reached the pulp, or nerve center of the tooth, a more complex intervention is required. This advanced decay necessitates a root canal to remove the infected pulp tissue and save the tooth. Following a root canal, a dental crown is typically placed over the tooth to restore its strength and protect it.