A root cavity (root caries) is decay that develops on the tooth’s root surface, typically near or just below the gum line. Common in adults, this occurs when aging or other factors expose the root structure. Unlike the visible part of the tooth, the root lacks protective enamel, making it significantly more vulnerable to decay. Because root cavities progress quickly and are often difficult to spot early, immediate professional attention is necessary to save the affected tooth.
Understanding Root Cavity Formation
The primary reason root surfaces become susceptible to decay is gingival recession, which is the movement of the gum tissue away from the tooth crown. This recession can be caused by periodontal disease, overly aggressive brushing, or simply the natural aging process. When the gums recede, they expose the cementum, which is the thin, soft layer covering the tooth root.
The cementum is substantially less mineralized than the enamel that protects the rest of the tooth, making it far more vulnerable to acid attack from plaque bacteria. While enamel requires a lower pH (around 5.5) to begin demineralizing, the softer cementum and underlying dentin can start dissolving at a higher, less acidic pH. This difference in composition means that decay on an exposed root surface can progress at least twice as fast as decay on the enamel surface.
Repair Options for Root Cavities
Non-Invasive Treatments
Treatment for a root cavity is determined by the depth and progression of the decay. For the earliest stage, where the lesion is small, non-invasive methods can stop the process. This involves applying high-concentration fluoride varnish or a medication called Silver Diamine Fluoride (SDF). SDF arrests decay by hardening the soft, infected tissue; the silver component acts as an antimicrobial agent, and the fluoride remineralizes the tooth structure.
Restorative Fillings
When decay has progressed to form a moderate-sized cavity, a restorative filling is necessary after the infected material is removed. Dentists frequently select Glass Ionomer Cement (GIC) for these repairs because the root surface is difficult to keep dry. GIC is preferred over traditional composite resin because it is less sensitive to moisture during placement and releases fluoride, offering a continuous localized defense against future decay. GIC is typically reserved for non-load-bearing areas of the root as it is not as durable as composite.
Severe Decay and Root Canals
If the root decay is severe and has penetrated deep into the dental pulp, endodontic intervention is required. Root canal therapy removes the infected nerve and blood vessels from the pulp chamber and root canals. The tooth’s interior is cleaned, disinfected, and sealed with a filling material. Following a root canal, the tooth often requires a crown to protect the weakened structure from fracture. In the most extreme cases, where decay has destroyed too much structure, extraction may be the only option to prevent infection spread.
Strategies to Prevent Root Decay
Preventing root decay centers on diligent daily hygiene and managing the risk factors that lead to root exposure and acid attack. The first line of defense is using a soft-bristled toothbrush with gentle strokes to prevent further gum recession near exposed root surfaces. Brushing twice daily with a fluoride toothpaste helps to strengthen the root surface against demineralization.
Individuals at high risk for root decay, such as those with dry mouth or a history of multiple root cavities, may benefit from a prescription-strength, high-fluoride toothpaste. This product typically contains a higher concentration of fluoride, providing greater remineralization potential than over-the-counter options. Dietary modifications are also important; reducing the frequency of consuming acidic foods, like citrus fruits and sodas, and sugary snacks starves the bacteria that produce decay-causing acids. Regular professional dental check-ups and cleanings are necessary to monitor gum health and apply professional fluoride treatments or spot early signs of root surface changes.