A root cavity (root surface caries) is decay that occurs on the tooth root surface when protective gum tissue recedes. This recession exposes the root, which is covered by cementum. Unlike the enamel-protected crown, the root surface is significantly softer and more porous. The cementum and underlying dentin demineralize quickly when exposed to acid from bacterial plaque, making the root highly susceptible to rapid decay.
Assessment and Determining the Treatment Path
A dentist begins treatment by assessing the exposed root surface using visual, tactile, and radiographic evaluation. The primary diagnostic method is a visual-tactile examination, checking the lesion’s characteristics, such as color and surface texture. An active, progressing lesion typically appears discolored (light brown to black) and feels soft or leathery upon gentle probing.
Conversely, an arrested lesion that is no longer decaying will present as dark, hard, and shiny. Bitewing radiographs are also employed to detect hidden decay or determine the lesion’s depth. This assessment classifies the cavity’s severity—superficial, moderate, or advanced to the pulp chamber—which guides the treatment decision toward conservative management or a more complex procedure.
Conservative Treatment Options
For superficial or non-cavitated root lesions, the initial approach focuses on arresting the decay and promoting remineralization. This is achieved through the professional application of topical fluoride varnishes, which contain high concentrations of fluoride ions. These ions are absorbed by the tooth structure, helping to rebuild lost mineral content and hardening the surface against further decay.
Another method for arresting existing root lesions involves the use of Silver Diamine Fluoride (SDF), a liquid substance painted directly onto the affected area. SDF works by utilizing silver to kill the decay-causing bacteria and fluoride to promote remineralization, effectively stopping the progression of the cavity. While highly effective, SDF permanently stains the treated area black, a cosmetic consideration often discussed with the patient beforehand.
When a root cavity is moderate, restorative treatment is necessary to fill the void. Specialized materials, particularly Glass Ionomer Cements (GIC), are often preferred for root surface restorations. GIC chemically bonds to the tooth structure and releases fluoride over time, which helps prevent secondary decay at the margin of the filling. These materials are also less sensitive to moisture near the gum line compared to traditional composite resins, leading to a more predictable and durable repair.
Invasive Procedures for Deep Root Cavities
When decay extends deep into the tooth structure, approaching or penetrating the central pulp chamber, a more invasive approach is required to save the tooth. Root canal therapy, or endodontic treatment, is performed when the bacterial infection has reached the pulp, causing irreversible inflammation or death of the tissue. During this procedure, the dentist removes the infected pulp, thoroughly cleans and disinfects the internal root canals, and then fills the space with an inert, rubber-like material called gutta-percha.
Following a root canal, the tooth often requires a dental crown to restore its original shape and provide structural reinforcement. The extensive removal of tooth structure during excavation and the root canal procedure weakens the remaining tooth, making the crown necessary to protect it from fracture. If the decay is so extensive that the tooth’s structure is severely compromised, or if the infection is too widespread, extraction becomes the final treatment option. Extraction is considered when the tooth is deemed non-restorable, such as when decay extends far below the gum line or due to severe bone loss.
Preventing Future Root Surface Decay
Long-term management of root health centers on preventing further gum recession and ensuring protective minerals reach the exposed surfaces. Proper brushing technique is paramount, requiring a soft-bristled brush and gentle pressure along the gum line to clean effectively without causing abrasion. The use of a high-fluoride prescription toothpaste is often recommended for individuals at high risk of recurrence.
Managing underlying systemic conditions, such as dry mouth, is a necessary step in prevention, as reduced saliva flow lowers the natural buffering capacity against acid. This can involve discussing medication side effects with a physician or using saliva substitutes. Additionally, modifying dietary habits by reducing the frequency of consuming acidic and sugary foods limits the fuel for decay-causing bacteria, which protects the vulnerable root surface.