Some sensitivity after a filling is completely normal and typically fades within a day or two. Sensitivity to hot, cold, or sweet foods may linger for one to two weeks. But if your pain is persistent, worsening, or spontaneous, something else may be going on. Several common issues can explain why a filled tooth keeps hurting, and most of them are fixable.
Your Bite May Be Slightly Off
This is one of the most common and easily corrected reasons for post-filling pain. Your jaw exerts up to 70 pounds per square inch on your molars, so even a filling that sits a fraction of a millimeter too high creates real discomfort every time you chew. You’ll notice it most when biting down, and the pain may feel sharp or concentrated on that one tooth.
This problem, called a high occlusion, happens because your mouth was numb during the procedure. When your dentist asked you to bite down on that colored paper, you may not have been able to feel the difference. A quick appointment to shave the filling down slightly is usually all it takes. If chewing is your main trigger and the pain started right after the procedure, this is the most likely culprit.
The Filling Material Itself Can Cause Sensitivity
Modern tooth-colored (composite resin) fillings harden under a curing light, and as the resin sets, it shrinks by about 2 to 3 percent. That small contraction pulls on the bond between the filling and your tooth, creating tiny gaps at the margins. These gaps allow fluid to seep in and irritate the nerve, a process called microleakage. The result is sensitivity to temperature changes and, in some cases, lingering discomfort that can take a couple of weeks to settle down.
This shrinkage stress is the primary drawback of composite fillings. Dentists use layering techniques and specific bonding agents to minimize it, but some post-procedure sensitivity from this mechanism is expected, especially with deeper fillings.
Why Temperature Triggers Pain
Your tooth contains thousands of microscopic channels called dentinal tubules that run from the outer layer of the tooth straight to the nerve. Each tubule is filled with fluid. When something hot, cold, or sweet touches the tooth, it causes that fluid to shift. The movement creates a tiny pressure change inside the tooth that excites nerve endings, and your brain registers it as a sharp zing of pain.
Drilling away decay to place a filling can expose more of these tubules, making the nerve temporarily more reactive to stimulation. This is normal and usually calms down within one to two weeks as the tooth adjusts. Using a desensitizing toothpaste during this period can help block those tubules and reduce the sensation.
The Nerve May Be Inflamed
The process of removing decay and placing a filling is inherently irritating to the pulp, the soft tissue inside your tooth that contains the nerve and blood supply. Some degree of inflammation afterward is expected. What matters is whether that inflammation is temporary or permanent.
Reversible Pulpitis
This is the good outcome. The nerve is irritated but capable of healing. You’ll feel a brief, sharp pain when something cold or sweet hits the tooth, but it disappears within a couple of seconds once the trigger is removed. The pain never shows up on its own, and it doesn’t wake you up at night. Given time, it resolves without further treatment.
Irreversible Pulpitis
This is the more serious scenario. The nerve inflammation has progressed beyond the point of self-repair. The key differences are specific and recognizable: pain lingers for 30 seconds or longer after exposure to hot or cold, pain appears spontaneously without any trigger, and over-the-counter pain relievers don’t do much to help. Some people notice the pain gets worse when lying down or bending over. This type of inflammation requires root canal treatment because the nerve will not recover on its own.
The shift from reversible to irreversible pulpitis can happen when decay was deep and close to the nerve, or when the procedure itself pushed the already-stressed pulp past its ability to heal. If your pain is escalating rather than gradually improving, that’s the pattern to pay attention to.
Less Common Causes Worth Knowing
Allergic reactions to filling materials are rare but possible. Composite fillings contain plastic resin and ground glass particles, and some people react to the resin or its additives. Amalgam (silver) fillings contain a mix of metals including mercury, silver, tin, and copper, any of which could trigger a sensitivity in certain individuals. Symptoms of an allergic reaction look different from normal post-filling soreness: localized swelling of the gums, itching or a rash around the mouth, or in severe cases, difficulty breathing. These symptoms typically appear shortly after placement and don’t resemble the gradual sensitivity pattern of normal healing.
A cracked or poorly sealed filling can also cause ongoing pain. If the filling doesn’t fully seal the cavity, bacteria can work their way underneath and cause new decay (called secondary caries), which produces pain that gets worse over time rather than better.
What a Normal Recovery Looks Like
General soreness from the procedure itself should fade within a day or two. Temperature and pressure sensitivity commonly lingers for one to two weeks before gradually disappearing. The trend matters more than any single day. If the pain is a little less intense on day five than it was on day two, you’re on the right track. If it’s the same or worse after two weeks, something beyond normal healing is likely happening.
Pain that is spontaneous (waking you up, appearing without a trigger), that throbs rather than zings, that responds poorly to pain medication, or that comes with visible swelling or fever points to a problem that needs professional attention. These patterns suggest either irreversible nerve damage or infection.
Managing Discomfort While You Heal
The American Dental Association recommends combining ibuprofen and acetaminophen for dental pain. A standard approach is 400 mg of ibuprofen (two standard pills) taken with 500 mg of acetaminophen. This combination targets pain through two different mechanisms and tends to work better than either one alone.
Beyond medication, a few practical adjustments help during the first couple of weeks. Chew on the opposite side of your mouth. Avoid very hot or very cold foods and drinks. Use a desensitizing toothpaste containing potassium nitrate, which helps calm the nerve endings inside those dentinal tubules. Switch to a soft-bristled toothbrush if you haven’t already, and avoid aggressive brushing around the filled tooth.
If your pain is clearly triggered only when you bite down and doesn’t respond to these measures within a few days, call your dentist and ask about a bite adjustment. It’s a five-minute fix that can eliminate the problem entirely.