Getting a cavity filled is not painful for most people. The numbing injection at the start of the procedure blocks virtually all sensation in the tooth and surrounding tissue, so you’ll feel pressure and vibration but not pain. The part people dread most is usually the needle itself, and even that is a brief pinch that lasts a few seconds.
What You’ll Feel During the Procedure
Before any drilling begins, your dentist numbs the area with a local anesthetic, typically injected into the gum near the affected tooth. The drug works by blocking nerve signals, which means the tooth and surrounding tissue can’t send pain messages to your brain. Within two to three minutes, the area goes numb.
Once the anesthetic kicks in, the dentist removes the decayed portion of the tooth using a small drill or other instrument. What you’ll notice during this step is vibration, pressure, and the sound of the drill. None of this should hurt. If you feel any sharpness or zing, tell your dentist. They can add more anesthetic before continuing. After the decay is cleared out, the dentist packs the filling material into the cleaned-out space, hardens it with a UV curing light (for tooth-colored fillings), polishes the surface, and checks your bite. The whole process for a single filling typically takes 20 to 40 minutes.
The Needle: The Part People Worry About
The injection is the only moment during a filling that involves real discomfort, and it’s brief. Most dentists apply a topical numbing gel to the gum tissue before inserting the needle. This gel contains benzocaine, which temporarily deadens the surface nerves. Research published in Anesthesia Progress found that patients who received a topical benzocaine gel before the injection reported significantly less pain on needle penetration compared to those who didn’t get it.
If needles make you anxious, it’s worth knowing that some dental offices now use computer-controlled delivery systems. These devices inject the anesthetic at a slow, consistent rate and pressure, which can make the injection nearly imperceptible. You can ask your dentist whether they offer this option.
How Long the Numbness Lasts
The numb feeling doesn’t disappear the moment you leave the chair. For the most commonly used anesthetic (lidocaine with a vasoconstrictor), expect the tooth itself to stay numb for about 85 minutes, while your lip, cheek, and surrounding soft tissue can remain numb for roughly three hours. Another widely used anesthetic, articaine, tends to last even longer, with effects ranging from about two and a half to over five hours depending on the individual.
This lingering numbness is the main reason dentists recommend waiting one to three hours before eating, especially if you had a composite (tooth-colored) filling. You won’t be able to feel temperature or pressure accurately, so you risk biting your cheek or burning your mouth on hot food. For silver amalgam fillings, the recommendation is to wait a full 24 hours before chewing on that side, since the material takes longer to fully harden.
Sensitivity After the Filling
Once the numbness wears off, you may notice some sensitivity. This is normal and not the same as the pain of the original cavity. The tooth might feel tender when you bite down, or react to hot, cold, or sweet foods and drinks. For most people, this sensitivity is mild and fades within one to three days.
Clinical studies tracking patients after composite fillings found that about 15% reported some sensitivity two days after the procedure, but by one week that dropped to around 4%. By 30 days, no patients in that study reported ongoing sensitivity, and across multiple studies, sensitivity consistently resolved within 90 days even in the most stubborn cases. Choosing softer foods and avoiding very hot or cold drinks during the first few days helps you get through this window comfortably.
When Post-Filling Pain Isn’t Normal
There’s one common issue that can cause persistent discomfort after a filling: a bite that’s slightly off. When your mouth is numb during the procedure, it’s hard to tell your dentist exactly how your bite feels. If the new filling sits even a fraction too high, you’ll notice it once sensation returns. Signs of this include one side of your teeth feeling higher than the other, tenderness when chewing on that tooth, or a sense that you’re hitting one tooth before the rest when you close your mouth.
This is an easy fix. Your dentist can shave down the high spot in a quick appointment, usually without any numbing needed. Don’t ignore it, though. A filling that sits too high puts extra force on the tooth’s root ligaments, which can lead to increasing soreness and inflammation over time. If your bite still feels off a day or two after the procedure, call your dentist to schedule an adjustment.
Sharp, spontaneous pain that comes on without chewing, or sensitivity that gets worse rather than better over the first week, can signal a deeper issue like irritation of the tooth’s nerve. This is uncommon but more likely with very deep cavities where the decay was close to the nerve. Your dentist will want to evaluate this and may take an X-ray to determine the next step.
Options for People With Dental Anxiety
If you’ve been putting off a filling because you’re afraid it will hurt, you have more options than just white-knuckling through it. Beyond the topical numbing gels and computer-controlled injection systems already mentioned, many dental offices offer some form of sedation for anxious patients. Nitrous oxide (laughing gas) is the lightest option: you breathe it through a small mask, it takes the edge off anxiety within minutes, and the effects wear off almost immediately after the mask comes off. For more intense anxiety, oral sedation or IV sedation are available at some practices, though these require someone to drive you home.
Some offices also use laser technology to remove decay instead of a traditional drill. Lasers can reduce or eliminate the need for anesthetic injections in certain cases, since they cause less vibration and pressure on the tooth. They also tend to result in faster healing afterward. Not every cavity is a candidate for laser treatment, and availability varies by practice, but it’s worth asking about if the drill is what scares you most.