A dental filling restores a tooth by replacing decayed or damaged tooth structure with a restorative material. While fillings are designed to be durable and protect the tooth, they do not make the tooth immune to future decay. It is possible for a new cavity to form on a tooth that has already been filled, often called “recurrent” or “secondary” decay. This can develop around or underneath an existing filling, requiring further dental intervention.
How Decay Can Form Around or Under a Filling
New decay can develop around an existing filling primarily due to marginal gaps or leakage. Over time, the bond between the filling and tooth can weaken, or the material may shrink or expand with temperature changes. These movements create tiny spaces at the interface where bacteria and food particles can accumulate and seep underneath, initiating new decay.
Fillings are subject to wear from chewing. Materials can degrade, chip, or crack, compromising the seal. This breakdown exposes tooth surfaces, allowing acid-producing bacteria to colonize and demineralize enamel or dentin, leading to a new cavity.
A new cavity can also form on a different part of the same tooth not initially affected or covered by the filling. For instance, decay might develop on an adjacent side surface if a filling is on the chewing surface. Poor oral hygiene or increased consumption of sugary foods and acidic beverages also heighten the risk of new decay, regardless of prior dental work.
Recognizing the Signs of Decay Around a Filling
Several indicators may suggest the presence of new decay around an existing filling. Increased sensitivity to hot, cold, or sweet foods is a common sign. This often occurs as decay progresses closer to the tooth’s nerve.
Localized pain, especially when biting or applying pressure, can also signal recurrent decay. Visible changes may include a dark spot or discoloration around the filling’s edge, or a rough or chipped edge. Food frequently getting trapped around the filled tooth, even after brushing, can also be a clue.
A patient might feel the filling has become loose or the tooth feels different when chewing. While these are strong indicators, a definitive diagnosis requires a professional dental examination. A dentist uses visual inspection, dental instruments, and X-rays to confirm new decay.
Preventing Decay After a Filling
Maintaining excellent oral hygiene prevents new decay after a filling. This includes brushing twice daily for two minutes with fluoride toothpaste and flossing at least once a day to remove plaque and food debris from all tooth surfaces, including around existing restorations. Consistent plaque removal minimizes acid attacks that lead to demineralization.
Regular dental check-ups and professional cleanings are important. These visits allow a dentist to monitor existing fillings, identify early signs of wear or marginal leakage, and detect new decay before it becomes extensive. Professional cleanings also remove hardened plaque (calculus) that cannot be removed by brushing alone.
Dietary habits play a role in preventing recurrent decay. Limiting sugary foods and drinks, and acidic beverages, reduces the fuel for acid-producing bacteria. Incorporating fluoride, through fluoridated water or rinses, strengthens tooth enamel and makes it more resistant to acid erosion. Addressing teeth grinding (bruxism) is also important, as excessive force can stress fillings and surrounding tooth structure, potentially leading to cracks or compromised seals.
What Happens If a Cavity Forms After a Filling?
If a cavity forms after a filling, a dentist will first diagnose the extent of the decay. This involves a visual inspection, probing the tooth with a dental explorer for soft spots, and reviewing X-rays, which can reveal hidden decay. Early detection preserves natural tooth structure.
Treatment options depend on the severity and location of the new decay. For small areas, the existing filling and decayed tooth structure are removed. A new, often slightly larger, filling is then placed to restore the tooth’s form and function. This procedure is straightforward and replaces the compromised restoration and tissue.
If decay is extensive and has weakened the remaining tooth structure, a dental crown may be necessary. A crown covers the entire visible portion of the tooth, providing strength and protection. If decay reaches the tooth’s pulp (containing the nerve and blood vessels), a root canal procedure is required to remove infected tissue, followed by a crown. In severe cases where the tooth is too damaged, extraction might be the only option.