A dental filling is a restorative material used to fill a cavity after decayed tooth material has been removed. A dental crown, often called a cap, is a custom-made covering that encases the entire visible portion of a tooth above the gum line. It restores the tooth’s shape, size, strength, and appearance. Placing a dental crown over an existing filling is a common practice to provide further protection and support.
Conditions for Crowning a Filled Tooth
Placing a crown over a tooth with an existing filling depends on several dental health criteria. A primary consideration is the amount of healthy tooth structure remaining after any decay or old filling material is removed. If there is not enough natural tooth structure to support a new filling, a crown becomes a more suitable option to provide strength and longevity.
The integrity and size of the existing filling also play a role. A large filling or multiple fillings in a single tooth can weaken its overall structure, making it more susceptible to cracks or fractures. A dentist will also assess for any active decay underneath the existing filling, as this decay must be thoroughly removed before a crown can be placed. The health of the tooth’s pulp, or nerve, is evaluated to ensure no underlying infections or inflammation. A thorough dental examination, often including X-rays, determines the tooth’s suitability.
Reasons to Crown a Filled Tooth
Dentists often recommend crowning a tooth that already has a filling when its structural integrity is compromised. For instance, if a large filling has left the tooth walls thin and vulnerable to fracture under chewing forces, a crown provides comprehensive coverage. This protects the weakened tooth from further damage and restores its original strength.
Another common reason for a crown is the presence of cracks or fractures in a tooth with a filling. These cracks can spread and deepen. A crown encapsulates the tooth, holding fractured pieces together and preventing crack progression. After a root canal treatment, a tooth often becomes brittle, and a crown is placed to protect it from fracturing and restore its function. Crowns also prevent bacteria from entering and causing further decay, especially if an old filling starts to wear away.
The Crowning Procedure for a Filled Tooth
The procedure for placing a dental crown on a tooth with an existing filling typically involves two appointments. During the first visit, the dentist prepares the tooth by removing a layer of its outer surface and shaping it. Preparation may involve removing some or all of the old filling, particularly if decay is present or if the filling needs replacement. If significant tooth structure is missing, the dentist may perform a “build-up” using a composite material to create a stable base for the crown.
After shaping the tooth, an impression is taken, either with a putty-like material or a digital scanner, to create a precise mold of the prepared tooth and surrounding teeth. This impression is sent to a dental lab where the custom permanent crown is fabricated, a process that can take about two to three weeks. A temporary crown is placed over the prepared tooth during this waiting period to protect it. During the second appointment, the temporary crown is removed, and the permanent crown is cemented onto the tooth using dental adhesive after ensuring a precise fit and proper bite alignment.
Ensuring Success After Crowning
The success of a crown placed over a filled tooth depends on several factors, including the chosen crown material. Materials like porcelain, zirconia, or porcelain-fused-to-metal offer varying levels of durability and aesthetics, and the dentist will select the most suitable option based on the tooth’s location and chewing forces. A precise fit of the crown and proper bite alignment are also important to prevent uneven pressure and damage to the crown or opposing teeth.
At-home oral hygiene practices are also important for the crown’s longevity. This includes brushing twice daily with fluoride toothpaste and flossing around the crowned tooth to prevent plaque buildup and decay at the crown’s margins. While the crown itself cannot decay, the natural tooth structure underneath and around it remains susceptible. Regular dental check-ups are also recommended to monitor the crown’s condition, identify any issues early, and ensure the surrounding gum tissue remains healthy.