Cavities form on the side surfaces of teeth through a process known as demineralization caused by acid. Tooth decay, or dental caries, occurs when bacteria in plaque consume sugars and starches, producing acid as a byproduct. This acid slowly erodes the protective enamel surface, creating tiny openings. While many people associate cavities with the chewing surfaces, decay frequently begins in areas difficult to clean, including the smooth side surfaces. A cavity can develop anywhere plaque accumulates and produces acid.
Specific Locations for Side Decay
Decay on the side of a tooth manifests in two distinct locations. The most common type is interproximal decay, which forms on the surface between two adjacent teeth, right where they touch. These hidden lesions are challenging because they are often invisible during a standard visual examination.
A second type is cervical decay, also referred to as smooth surface decay, which occurs near the gum line. This decay affects the smooth, outer surface of the tooth near the neck (cervix). If the gum has receded, exposing the softer tissue below the enamel, cervical decay can be considered a root cavity.
Factors That Increase Risk in These Areas
The tight spaces between teeth create an ideal environment for plaque accumulation, which is the primary reason for interproximal decay. The contact points trap food debris and bacterial plaque, shielding them from the bristles of a toothbrush. Ignoring daily flossing leaves this area vulnerable, allowing bacteria to constantly produce acid against the enamel surface.
The vulnerability of the cervical area is increased by gum recession, which exposes the underlying tooth structure. Unlike the crown, which is covered in hard enamel, the root surface is covered by a softer material called cementum. Once exposed, this cementum and the underlying dentin are much more susceptible to acid erosion and decay.
Aggressive horizontal brushing can also contribute by causing the gums to recede, exposing the softer root surface. A lack of saliva flow, known as dry mouth, increases the risk everywhere, as saliva naturally helps rinse away food particles and neutralize acids. Consistent snacking on sugary or acidic foods provides a constant fuel source for the plaque bacteria in these hard-to-reach spots.
Diagnosis and Repair
Because interproximal decay is hidden between adjacent teeth, it often goes undetected until significant damage has occurred. Dentists rely on bitewing X-rays for an accurate diagnosis, as these images reveal the decay as a shadow or radiolucency between the teeth. X-rays can detect decay in these areas long before it becomes visible or causes symptoms.
Once a side cavity is confirmed, the standard treatment involves removing the decayed material and repairing the tooth with a filling. For small lesions, the dentist uses a minimally invasive approach, restoring the area with a composite resin, a tooth-colored material. The repair process restores the proper contour and contact point between the teeth while removing the decay. Early detection through regular checkups and X-rays preserves the maximum amount of healthy tooth structure.