In almost all cases, a dental filling is the best solution for a cavity caused by tooth decay. Once the procedure is done, patients are often surprised to still have some sensitivity or even pain. This is normal—to a degree. But if sensitivity is extreme or lasts too long, it could mean there is a problem. How long should a cavity filling be sensitive before seeking help?

What to Expect Immediately After Getting a Filling

Most people experience mild sensitivity right after a tooth is filled. This usually lasts no more than a few hours and often has more to do with the anesthetic wearing off than the filling itself.

Dentists often use the local anesthetic drug novocaine so they can put in a filling without the patient feeling any pain. Injecting novocaine with a syringe numbs the tooth with the cavity and the surrounding area. Within just five or ten minutes, the patient will not be able to feel the dentist using a drill and other dental instruments to fix the tooth. In fact, many people feel that the stick of the needle administering the drug is the most painful part of the cavity filling process.

Novocaine can leave patients with an odd feeling after the procedure is done. The area of the injection site will stay numb for about 30 to 60 minutes. This can include the gum, lips, tongue, and cheeks. Because there is no feeling for a while, some people describe the sensation as if they were touching someone else’s face rather than their own. Then, as the numbness wears off and sensation returns, it may feel tingly, prickly, or itchy.

Even after the novocaine is out of the system, a newly filled tooth can feel sensitive to heat, cold, or biting down. In most cases, patients are back to normal by the next day, able to eat and drink what they please without noticing any sensitivity or pain.

When to Seek Help for Tooth Sensitivity

While the majority of cavity fillings stop being sensitive after a day or two, some could take as much as two weeks to feel better. Even then, it may not be a cause for concern. If a cavity was deep or in a location used for heavy chewing, it might take longer to heal. Sensitivity during the healing process is expected.

There are some things that patients should watch for, however. These symptoms could indicate that that is a problem beyond normal sensitivity. 

• Extreme sensitivity that makes it hard to eat or drink
• Sharp or throbbing pain similar to a toothache
• Sensitivity or pain that gets worse over time
• Redness, irritation, or a rash on the surrounding tissue
• A feeling like the teeth do not fit together properly

It is best to contact the dentist right away when experiencing any of these things beyond the first few days. They will either offer some remedies you can try or have you come in so they can check to see if anything is wrong with the filling. Dental fillings are meant to fix cavity pain. There is no reason a patient should feel they need to just “tough it out” if they are feeling discomfort.

Why Do Fillings Cause Tooth Sensitivity?

There are a number of reasons why filling teeth causes sensitivity. Some are normal reactions to the process itself. These result in the sensitivity that goes away quickly. Sometimes, however, the discomfort could mean that the procedure was not successful or that there is an underlying issue besides the cavity. In these cases, the dentist may need to replace the filling or perform additional dental work to fix the problem.

Drilling

The act of drilling can itself make a tooth sensitive. A deep cavity means the dentist might need to drill close to the root. The heat and vibration from the dental drill can inflame and irritate the nerves and blood vessels at the core of the tooth. In most cases, the sensitivity caused by this inflammation will go away once the tooth root heals.

Large or Multiple Fillings

Just as a deep cavity might be more sensitive than a shallow one, so will a filling that covers a large portion of the tooth’s surface. A big filling, or adding more filling material to a tooth that’s already been filled can have the same effect. If a tooth gets to the point where it is made up of more filling material than natural tooth, another option, such as a root canal procedure should be considered.

Pulpitis

A cavity is the result of bacteria building up on the tooth and eating away the enamel. Left untreated, it will eventually cause a painful infection called pulpitis. If the dentist fails to remove all of the infected tissue, pulpitis can be left behind, trapped inside the tooth by the filling. This condition can quickly go from sensitivity to pain. The dentist will at the very least need to redo the filling. If pulpitis has taken hold, causing an abscess, a root canal procedure might be needed to fix it.

Bad Bite Alignment

As part of the dental filling procedure, dentists typically do a bite test. This ensures that they have shaped the surface of the filled tooth to match the natural contours of the original tooth. If the shape of the filling material is off by even a tiny amount, it can interfere with the way the top and bottom teeth fit together. This will add to the sensitivity of the tooth when biting down and can cause pain and discomfort not only for the rest of the teeth but the entire jaw. The dentist can easily fix this by filing and polishing the filling until it is in the correct shape.

Allergic Reactions and Galvanic Shock

In a few rare cases, the materials used to fill a tooth can cause a reaction in the patient. Some patients are allergic to gold or amalgam fillings (commonly known as silver fillings). This may present as a rash or irritation on the gums and lips, or sensitivity. Galvanic shock is a phenomenon that occurs when a gold filling touches a silver filling. It can cause a feeling like an electric shock. Both of these situations can be remedied by having the filling replaced with another material such as composite resin or porcelain.

Managing Pain and Sensitivity From a Dental Filling

How long a cavity filling should be sensitive is different for everyone. If not much time has passed since the procedure, or if a patient is not sure if they should be concerned about their level of sensitivity, there are a few things they can try before contacting the dentist.

• Over-the-counter pain relievers such as acetaminophen or ibuprofen
• Use toothpaste labeled for sensitive teeth
• Brush and floss gently
• Try topical oral analgesics
• Avoid eating and drinking hot, cold, acidic, or sweet things
• Do not bite down on ice or hard or chewy foods like nuts or toffee
• Avoid teeth whitening products

If these remedies do not help with a tooth’s sensitivity or pain within a few days or weeks, contact the dentist. They will be able to assess the reason for the discomfort and come up with a solution.

If you think you have a cavity, do not hesitate to get it fixed. Tooth decay will not go away on its own. Left untreated it can cause much more pain and increase the danger of losing the tooth. If you need to find a dentist, you can start the process of finding a dental professional near you with our make an appointment tool.