When tooth decay occurs on the smooth surfaces between adjacent teeth, it is known as an interproximal cavity. This location presents a unique challenge for dentists compared to decay found on the chewing surface of a tooth. The procedure requires removing the decayed material and navigating the narrow, enclosed space where the teeth touch. Successfully treating this type of cavity depends on recreating the precise anatomical shape and the tight contact point with the neighboring tooth.
Preparing the Tooth and Removing Decay
The filling procedure begins with administering a local anesthetic to numb the area. Once the area is numb, the dentist must establish a clean, dry working environment, which is achieved through isolation. This often involves placing a rubber dam around the affected tooth to keep saliva and moisture away from the preparation site. Dryness is necessary because modern restorative materials cannot bond properly to a contaminated tooth surface.
Access to the decay is usually created by drilling a small opening through the top or chewing surface of the tooth. Using a high-speed dental handpiece, the dentist carefully removes the carious enamel and dentin. The goal is to eliminate all soft, infected tissue while preserving as much healthy tooth structure as possible. This meticulous preparation creates a clean foundation and a specific cavity shape that will securely hold the final restorative material.
Rebuilding the Missing Wall with Matrix Systems
Once the decay is cleared, the dentist faces the problem of the missing proximal wall, the side of the tooth that meets its neighbor. Without this physical barrier, any filling material placed would simply flow out into the space between the teeth, making a successful restoration impossible. Specialized matrix systems are employed to temporarily replace the absent tooth structure and create the necessary boundary.
These systems utilize a thin, contoured metal or clear plastic called a matrix band. The band provides the mold against which the filling material will be packed and shaped. A wedge is inserted from the tongue or cheek side to seal the matrix band at the bottom edge.
The wedge serves two distinct purposes: it seals the gingival margin to prevent material leakage, and it creates a slight, temporary separation of the teeth. The separation ensures the newly filled tooth presses firmly against its neighbor, establishing a tight contact point.
Dentists frequently use sectional matrix systems, employing small, curved matrix bands held in place by a tension ring. The rings apply pressure to the band, helping to recreate the natural, convex curvature of the tooth surface. Larger preparations may require a Tofflemire retainer. This system holds a circumferential band that encircles the entire tooth, providing robust support for the filling material during placement.
Placing the Restoration and Sculpting the Surface
With the matrix and wedge securely in place, the tooth surface is prepared for the composite resin material. First, a conditioning gel, typically phosphoric acid, is applied to the enamel and dentin surfaces to microscopically roughen the surface, a process called etching. A liquid bonding agent is applied and is cured with a blue light to create a strong adhesive layer.
The composite resin, a tooth-colored paste, is then placed into the preparation in small increments, or layers. Each layer is individually cured using a high-intensity light. This layering technique minimizes shrinkage of the composite material as it hardens and ensures a complete, uniform cure throughout the depth of the restoration.
Once the final layer is cured, the temporary matrix band and wedge are carefully removed, revealing the new proximal wall and contact point. The dentist then uses fine finishing burs and abrasive discs to refine the shape of the filling and adjust the patient’s bite (occlusion). This final sculpting mimics the natural grooves and contours of the adjacent teeth for proper function and hygiene.
Immediate Post-Procedure Expectations
Following the procedure, patients will experience temporary numbness in the area, which typically lasts for a few hours. It is advisable to avoid chewing on the treated side until sensation returns to prevent accidentally biting the tongue, cheek, or lips. Some temporary sensitivity to hot or cold temperatures is common, especially if the original decay extended deep into the dentin layer.
This thermal sensitivity usually subsides within a few days or weeks as the tooth recovers. If the bite feels “high” or uneven after the numbness wears off, or if the sensitivity is severe and persists beyond a couple of weeks, the patient should contact the dental office. A simple adjustment to the restoration’s height can often resolve occlusal issues quickly.