An interproximal cavity forms on the side of a tooth where it contacts an adjacent tooth. These cavities are challenging because the decay is hidden from view in the tight space where two teeth meet. Unlike easily accessible cavities on the chewing surface, interproximal decay requires specialized techniques to recreate the tooth’s natural contour and ensure proper contact with the neighboring tooth. This complexity is why interproximal cavities are commonly discovered through routine dental X-rays, often before they cause noticeable symptoms. The restoration procedure requires specialized tools to build a temporary wall where the natural tooth structure is missing.
Initial Preparation and Decay Removal
The initial step involves administering a local anesthetic to ensure patient comfort. Once the area is numb, the dentist isolates the tooth from the rest of the mouth, typically using a rubber dam or cotton rolls. Maintaining a moisture-free field is important when using composite materials, as moisture can compromise the filling’s bond strength.
Access to the decay is established by drilling through the top or chewing surface of the tooth to reach the side wall where the cavity lies. Using a high-speed dental handpiece, the decayed enamel and dentin are meticulously removed until only healthy tooth structure remains. The dentist shapes the resulting hollow space, known as the preparation, to ensure it can mechanically lock in the filling material and adequately support the final restoration.
This preparation must be performed with precision because the adjacent healthy tooth is in close proximity. The goal is to remove all signs of bacterial infection while preserving as much healthy tooth structure as possible. The final cavity design must allow for the placement of the restorative material and the specialized tools needed to form the new tooth wall.
Rebuilding the Missing Tooth Wall
The defining challenge of an interproximal filling is the missing wall where the tooth touched its neighbor. To successfully place the filling material, a temporary boundary must be established using a matrix system. This matrix acts as a mold, providing the necessary wall against which the material is packed, ensuring the final restoration has the correct anatomical shape.
For posterior teeth, dentists frequently use sectional matrix systems, which feature a small, contoured metal band placed around the prepared section. A retainer ring holds the band firmly in place and creates a slight separation between the teeth. This temporary separation compensates for the matrix band’s thickness, ensuring the completed filling creates a tight, natural contact point with the adjacent tooth when the system is removed.
A small, wedge-shaped device, made of wood or plastic, is inserted near the gum line below the contact area. The wedge serves a dual purpose: it presses the matrix band tightly against the tooth’s edge, preventing the filling material from spilling out and creating an overhang. It also contributes to the slight separation of the teeth, which is essential for achieving a proper, snug contact point. The sectional matrix band is pre-contoured to mimic the convex curve of a natural tooth surface.
Material Placement and Contouring
With the matrix system and wedge securely in place, the tooth receives the restorative material, typically tooth-colored composite resin. Before application, the prepared surface is treated with an etching gel and a bonding agent to microscopically roughen the surface and chemically prepare it for adherence. This step is foundational for creating a strong, lasting bond between the tooth and the filling material.
The composite resin is applied in small layers, usually no thicker than two millimeters, a technique known as incremental layering. This layering allows the dentist to sculpt the material effectively and minimizes the effects of polymerization shrinkage. Since composite shrinks slightly as it cures, placing it in thin increments helps manage this stress, reducing the chance of gaps forming at the edges of the filling.
Each layer of the composite is hardened using a high-intensity curing light, which initiates the chemical setting process. Once the final layer is cured, the temporary matrix band and wedge are carefully removed, revealing the newly formed side of the tooth. The dentist then uses fine diamond burs and finishing strips to refine the shape, ensuring the filling is smooth and seamlessly integrated with the natural tooth contours.
Post-Procedure Expectations
Following the filling procedure, temporary sensitivity in the treated tooth, particularly to hot and cold temperatures, is common. This sensitivity is a normal part of the healing process after decay removal and typically subsides within a few days to a couple of weeks. Since composite fillings are set immediately by the curing light, patients can generally eat and drink once the local anesthetic has worn off.
Patients should monitor their bite in the days following the appointment, as the new filling may initially feel slightly different or “high.” If the bite continues to feel uneven after a few days, or if sensitivity persists beyond two weeks, the patient should contact the dental office for an adjustment. A high spot on the filling can cause discomfort and requires a quick adjustment to smooth the surface and restore proper function.