Why Does My Filling Hurt Months After It Was Placed?

By Lovik Mirzaeian, DDS. Updated October 2026.

A filling that hurts months after it was placed is usually caused by one of four things: the filling sits slightly high and takes too much bite force, the filling or the tooth around it has cracked, the seal at the edge has failed and let bacteria in, or the nerve under the filling has become inflamed and is not settling down. Mild sensitivity in the first couple of weeks is normal. Pain that appears or persists months later is not, and it needs a look.

I tell every patient the same thing: some tenderness for a few days to a few weeks is expected. When someone comes back at month three or six with a tooth that hurts, the cause is nearly always findable, and most of the fixes are simple.

First, What Is Normal

Drilling irritates the nerve inside a tooth. The deeper the cavity, the closer we get to that nerve, and the longer it takes to calm down. Cold sensitivity, a little tenderness to biting, and an odd feeling for a week or two are all ordinary. Deep fillings can stay sensitive for a month or two and still be fine.

What should not happen: pain that is getting worse instead of better, pain that starts fresh after a quiet period, or pain that lingers for minutes after the trigger is gone. The American Dental Association has a general overview of what to expect after a filling. This post is about the ones that hurt later.

Cause One: The Bite Is High

This is the most common cause and the easiest to fix. When we shape a filling, you are numb, and it is hard to bite naturally. If the filling ends up even a fraction of a millimeter taller than the surrounding teeth, that tooth hits first every time you close. Chewing hammers it thousands of times a day.

The result is a tooth that is sore to bite on, sometimes tender to touch, and sometimes cold sensitive because the constant pounding inflames the ligament and the nerve. Some people notice it in the first week. Others adapt at first and then the tooth gradually becomes sore over a month or two.

The fix is a two-minute adjustment. We mark the bite with colored paper, shave the high spot, and the tooth typically settles within days. Do not wait it out. A high filling can eventually crack the tooth.

Cause Two: A Crack

A filling replaces lost tooth structure but does not make the tooth as strong as it was. Large fillings, especially on molars, leave thinner walls of natural tooth around them. Over months of chewing, one of those walls can develop a hairline crack. The filling itself can also crack, particularly a large one under heavy bite force.

The classic sign is a sharp pain when you bite on something and release, more than when you press down. It is often hard to pinpoint which tooth. Cold sensitivity is common. On an x-ray, the crack is usually invisible. We find it with a bite test, where you bite on a small plastic tool tooth by tooth until the sore one shows up.

A cracked tooth with a filling usually needs a crown to hold it together. If we catch it early, the nerve is often fine. Wait long enough and the crack can reach the nerve, at which point a root canal joins the plan.

Cause Three: A Leaking Margin

The margin is the edge where the filling meets the tooth. It should be sealed. Over time, especially with tooth-colored fillings that were not kept perfectly dry during placement, or with any filling that has flexed under load, that seal can open up microscopically. Saliva, bacteria, and sugar creep into the gap. Decay starts underneath the filling, out of sight.

Symptoms are sensitivity to sweets, sometimes to cold, and a dull ache that comes and goes. You may notice a dark line at the filling edge, or the floss may catch there. On an x-ray we can often see a shadow under the filling. The fix is to remove the filling, clean out the decay, and place a new one. If the decay went deep, a crown or root canal may be needed.

Cause Four: An Irritated Nerve That Will Not Settle

Sometimes the filling is fine, the bite is fine, there is no crack, and the tooth still hurts. This happens when the cavity was deep and the nerve was already stressed before we ever touched it. Most nerves recover. A few do not, and instead of calming down, the inflammation slowly progresses.

The signs are lingering pain after cold, spontaneous throbbing, pain that wakes you at night, and pain that responds to hot. These point toward the nerve dying, which is common and treatable. The treatment is a root canal, which removes the inflamed nerve and stops the pain. If that word makes you tense, read is a root canal really that painful. Modern root canals are far more comfortable than their reputation.

If a dying nerve is ignored, it can become infected and form an abscess. Swelling, a bad taste, a pimple on the gum, or pain that suddenly gets severe are signs to act quickly.

What to Note Before Your Visit

A few details make diagnosis much faster. Does it hurt to bite, or to release? Does cold hurt, and for how long after? Does hot or sweet hurt? Does it ever hurt on its own, or wake you up? Bring those answers and we can usually narrow it to one cause quickly.

When to See a Dentist

A filling that is sore to bite on, sensitive to sweets, or newly sensitive months after placement should be checked at a routine exam. Do not wait for your next scheduled cleaning if it has been going on more than a couple of weeks. If the pain is throbbing, waking you at night, or there is any swelling, call our emergency dentist line the same day.

Frequently Asked Questions

Is it normal for a filling to hurt months later?

No. Some sensitivity for a few days to a few weeks after a filling is normal, and deep fillings can take a month or two to settle. New or worsening pain months later usually means a high bite, a crack, a leaking edge, or an inflamed nerve, and it should be examined.

Why does my filling hurt when I bite down?

Pain on biting most often means the filling is slightly high and taking too much force, which is fixed with a quick adjustment. Sharp pain on release rather than pressure suggests a crack in the tooth, which usually needs a crown. A bite test at the office can tell the two apart.

Can a filling fail after a few months?

Yes. The seal at the edge can open and let bacteria in, decay can form underneath, or the filling or surrounding tooth can crack under chewing force. Sweet sensitivity, a dark line at the edge, or floss catching there are common signs. A replacement filling usually solves it if caught early.

When does a filled tooth need a root canal?

If pain lingers for minutes after cold, throbs on its own, responds to heat, or wakes you at night, the nerve inside may be dying and a root canal is usually the treatment. Swelling or a pimple on the gum near the tooth means infection and should be seen the same day.

Filling Still Bothering You? Dr. Mirzaeian Can Help

Most late filling pain has a simple explanation and a quick fix, and the ones that do not are much easier to treat early. Contact us to set up a consultation and we will find out what is going on.

Lovik Mirzaeian, DDS has achieved extensive training in multidisciplinary dental treatments. His credentials include Dental Implants, Cosmetic Dentistry, Full Mouth Reconstruction, Endodontics, Oral Surgery, Orthodontics, and Sleep Sedation. Our office puts your comfort and smile first, and we are dedicated to giving you top-notch dental care. Get ready to show off your perfect smile!

Looking for a trusted family dentist in Clovis? Dr. Mirzaeian welcomes new patients of all ages.