A filling can hurt for several reasons, ranging from completely normal post-procedure sensitivity to signs that something needs attention. Most filling pain falls into predictable categories, and the timing, type, and intensity of your pain tells you a lot about what’s going on.
Normal Sensitivity After a New Filling
If your filling is recent, some sensitivity is expected. The drilling process irritates the nerve inside your tooth, and composite (tooth-colored) fillings involve chemicals that bond to your tooth structure. Both of these can leave the nerve temporarily inflamed. Sensitivity typically peaks in the first 24 to 48 hours, then gradually fades. For most people it resolves within a week, though deeper fillings can take up to two weeks to fully settle down.
During this window, you might notice sharp twinges when eating something cold, hot, or sweet. This happens because tiny fluid-filled tubes run through the inner layer of your tooth, and when temperature changes cause that fluid to shift, it stimulates the nerve. A new filling can temporarily make those tubes more reactive. If sensitivity is mild, manageable, and getting a little better each day, it’s likely just your tooth adjusting.
Your Bite May Be Off
One of the most common and fixable reasons a filling hurts is that it’s slightly too high. When the filling sits even a fraction of a millimeter above your natural bite line, that tooth absorbs more force than it should every time you chew. You’ll notice the filled tooth and the tooth above or below it making contact before the rest of your teeth do. Your bite feels “off,” and the area gets sore.
What’s actually happening is the tooth is being pushed deeper into the ligament that anchors it to your jawbone. That ligament swells and becomes inflamed, producing a tender, aching pain that gets worse with chewing. The fix is simple: your dentist shaves down the high spot in a quick visit, and the pain usually resolves within a few days once the ligament calms down. This is one of the most common reasons people return after getting a filling, partly because your mouth was numb during placement and you couldn’t gauge your bite accurately.
Pain From Shrinkage Gaps
Composite resin fillings harden under a curing light, and as they harden, they shrink slightly. This shrinkage can pull the filling away from the walls of the tooth, creating microscopic gaps between the filling material and the underlying tooth structure. These gaps fill with fluid, and when you bite down, the pressure pushes that fluid through the tiny tubes in your tooth and straight toward the nerve. The result is a sharp pain specifically when chewing.
Composite fillings also expand and contract with temperature changes at a rate several times greater than your natural tooth enamel. This mismatch means hot coffee or ice water can widen those gaps temporarily, letting bacteria, fluids, and temperature changes reach deeper into the tooth. If biting pain persists beyond the first couple of weeks, it may indicate the bond between filling and tooth didn’t fully seal.
Nerve Inflammation Inside the Tooth
Sometimes a filling hurts because the nerve inside the tooth (the pulp) is inflamed. Dentists call this pulpitis, and it comes in two forms that feel different and have very different outcomes.
When the inflammation is mild and reversible, you’ll feel a quick, sharp zing in response to cold that stops almost immediately once the cold source is removed. The nerve is irritated but still healthy, and given time, it can heal on its own. This type of pain involves the fast-conducting nerve fibers in the tooth, and it’s the kind of sensitivity most people experience after a routine filling.
Irreversible inflammation feels different. The pain tends to linger well after the trigger is gone, sometimes for minutes at a time. Heat often makes it worse rather than cold. The ache can become spontaneous, waking you up at night or appearing without any obvious trigger. This type of pain involves deeper nerve fibers associated with tissue damage, and it means the nerve won’t recover. A tooth in this state typically needs a root canal or extraction.
The tricky part is that these two categories exist on a spectrum. A cold sensitivity that lingers for 10 seconds sits in a gray zone. The key pattern to watch is direction: is your pain gradually improving over days, or gradually getting worse?
Decay Under an Old Filling
If your filling is months or years old and starts hurting, the most likely culprit is new decay forming underneath or around the edges. Over time, the seal between a filling and your tooth can break down. Bacteria slip into the resulting gaps, and decay develops in a spot that’s invisible to you and sometimes hard to see even on an X-ray until it’s progressed.
There are a few warning signs beyond pain. Dark lines or gray shadows around the filling’s edges suggest leakage. If food frequently gets stuck around the filling, or your floss shreds or catches in that area, the margins may no longer be smooth. Increasing sensitivity to hot, cold, or sweet foods that wasn’t there before, especially appearing weeks or months after the filling was placed, often points to recurrent decay or a failing seal. This type of pain tends to build gradually rather than appearing overnight.
Signs of Infection
In some cases, bacteria that enter through a failing filling or deep decay reach the pulp, kill the nerve, and cause an abscess at the root tip. This produces a distinct set of symptoms that goes beyond ordinary filling sensitivity: severe, constant, throbbing pain that can radiate into your jaw, neck, or ear. Your face or cheek may swell. You might develop a fever, notice swollen lymph nodes under your jaw, or taste something foul if the abscess drains into your mouth.
An abscess won’t resolve on its own and can spread to surrounding tissues. Fever combined with facial swelling, or any difficulty breathing or swallowing, warrants urgent care.
Galvanic Pain Between Metal Fillings
If you have both a gold restoration and a silver amalgam filling, especially if they’re on opposing or adjacent teeth, you can experience a sharp, electric jolt when they touch. This happens because two different metals in saliva (which conducts electricity) create a small galvanic current, essentially a tiny battery in your mouth. It’s uncommon but distinctive: a sudden shock rather than a lingering ache. Zinc-containing amalgam fillings are particularly prone to this effect. The sensation often diminishes over time as the surface of the metal oxidizes.
What Helps in the Meantime
For mild post-filling sensitivity, desensitizing toothpaste containing potassium nitrate can make a real difference. The potassium ions travel down the fluid-filled tubes in your tooth and calm the nerve by interrupting pain signals. It takes consistent use over a week or two to build up, so it’s not an instant fix, but it’s effective for garden-variety sensitivity. Avoiding very hot and cold foods on that side for the first few days also helps.
If your pain is specifically when biting, try chewing on the other side and call your dentist to check the bite height. This is the single most common reason for a follow-up visit after a filling, and the adjustment takes minutes.
Pain that lingers after hot or cold exposure, spontaneous throbbing, or sensitivity that’s getting worse rather than better after two weeks are all signals that the issue goes beyond normal healing. The pattern of your pain, when it happens, what triggers it, how long it lasts, and which direction it’s trending, gives your dentist the most useful information for figuring out what’s going on.