Cavities frequently occur between teeth, making this one of the most common forms of tooth decay. This decay is known as an interproximal or proximal cavity, referring to the surfaces where teeth touch each other. These cavities are problematic because they are hidden from direct view and difficult to clean with a standard toothbrush. If left undetected, interproximal cavities can progress through the enamel and into the softer layers of the tooth, often requiring more extensive repair than a cavity found on a visible surface.
Why Decay Forms Between Teeth
The tight physical contact point between two adjacent teeth creates a sheltered niche perfect for bacterial accumulation. This small area becomes a retention zone where food debris and plaque, a sticky film of bacteria, become lodged and are not easily dislodged. The bacteria in this plaque feed on sugars and starches, producing acids that begin to dissolve the mineral structure of the tooth enamel in a process called demineralization.
This specific location is vulnerable because the natural defenses of the mouth cannot effectively reach the area. Saliva, which neutralizes acid and delivers minerals for remineralization, struggles to flow into the tight interdental space. Consequently, the acid attack is sustained for longer periods, accelerating the decay process.
How Dentists Find Interproximal Cavities
Interproximal cavities often go unnoticed by patients because they form below the contact point, where no visual symptoms appear until the decay is advanced. A dentist’s standard visual and physical examination, even with a small probe, may not be able to detect the decay in its early stages. The most reliable method for detection is the use of bitewing X-rays.
Bitewing radiographs are specifically angled to show the crowns of the back teeth in contact, providing a clear view of the enamel and dentin surfaces between them. On the X-ray image, healthy tooth structure appears light or white, while areas of decay show up as shadows or dark spots because the acid-eroded material is less dense. These images allow a dental professional to assess the depth of the decay, determining if it is confined to the outer enamel or has spread into the softer, inner dentin layer. X-rays remain the gold standard for accurately diagnosing the extent of hidden decay.
Repairing the Damage
Once an interproximal cavity is diagnosed, treatment typically involves a dental filling to remove the decay and restore the tooth’s structure. The dentist must first access the decayed area, which usually involves removing a small amount of healthy tooth structure from the top surface to reach the lesion between the teeth. A specialized metal band or matrix is often placed around the tooth to create a temporary wall, helping to rebuild the missing side surface.
The decayed material is carefully removed, and the prepared space is cleaned before the filling material is applied. Composite resin, a tooth-colored material, is the most common choice for interproximal fillings due to its aesthetic qualities and ability to bond directly to the tooth structure. The resin is placed in layers and hardened with a special light, restoring the tooth’s original contour and contact point with the adjacent tooth. If the decay is severe, a crown may be necessary to cover and protect the remaining structure from fracturing.
Essential Strategies for Interdental Cleaning
Standard brushing cleans the tops and outer surfaces of the teeth but is ineffective at removing plaque from the tight spaces between them. Cleaning the interdental area must be a distinct part of your daily hygiene routine to prevent these hidden cavities. Flossing is considered the traditional method for this task, requiring a specific technique to be effective.
To properly floss, you should use a clean section for each tooth. Wrap the floss into a C-shape around one tooth and gently slide it below the gumline. Rub the floss against the side of the tooth, moving it up and down several times to physically scrape away the accumulated biofilm. This C-shape motion ensures that the floss makes contact with the entire side surface of the tooth, not just the contact point.
Alternative Interdental Tools
For individuals who find traditional string flossing challenging, alternative tools offer different approaches to disrupting the interdental plaque. Consistency in using one of these interdental cleaning methods at least once a day is the most effective defense against the formation of interproximal cavities.
- Interdental brushes, which resemble tiny pipe cleaners, are available in various sizes to fit the spaces between teeth and can be highly effective for physically scrubbing the area.
- Water flossers, also known as oral irrigators, use a pressurized stream of water to flush out food particles and plaque from the tight gaps.