Tooth Sensitivity After a Filling: Causes and How to Stop It

You just left the dentist's office, cavity filled, feeling accomplished. Then you take a sip of water or bite into something, and—zing!—a sharp, fleeting pain shoots through that tooth. Sound familiar? Tooth sensitivity after a filling is incredibly common. It can range from a mild nuisance to a significant discomfort, and it often leaves patients wondering if something went wrong.

The short answer is this: mild to moderate sensitivity for a few days to a couple of weeks is usually normal. Your tooth has been through a minor surgical procedure. But knowing why it happens, what's normal, and what's a red flag can save you a lot of worry. More importantly, knowing what you can actually do about it puts you back in control.

Why Is My Tooth Sensitive After a Filling?

Let's break down the mechanics. A filling isn't just a plug. To place it, your dentist had to remove decayed tooth structure, which often involves drilling close to the inner living part of your tooth, the pulp. The pulp houses nerves and blood vessels. Even with the best techniques and anesthesia, the process creates inflammation.

Think of it like getting a splinter removed from your finger. Even after it's out, the area is tender, swollen, and reactive for a few days. Your tooth reacts similarly.

Here are the specific culprits behind that sensitive tooth after a filling:

1. The "Pulpitis" Reaction (Inflammation of the Nerve)

This is the primary driver. The drilling, the chemicals in bonding agents, and even the curing light can irritate the pulp. This inflammation causes fluid pressure changes inside the tiny channels in your dentin (the layer under the enamel), which the nerve interprets as pain. It's a sign your tooth is alive and responding to the trauma of treatment.

2. The Type and Depth of the Cavity

Not all fillings are created equal. A small, shallow filling on the biting surface is less likely to cause prolonged sensitivity than a deep one that got close to the pulp, or one on the side of the tooth near the gumline. Deeper cavities mean the dentist was working closer to the nerve, raising the odds of a more pronounced inflammatory response.

3. The Bite Might Be Off (A High Filling)

This is a sneaky one that patients often don't consider. After your numbness wears off, chew gently on that side. Does the tooth feel like it's hitting first or bearing more pressure than the others? Even a fraction of a millimeter of excess filling material can put tremendous force on the tooth, causing soreness and sensitivity to pressure. It feels like a bruise.

I've seen countless patients return thinking they needed a root canal, only to discover a quick bite adjustment solved everything. It's the first thing a dentist checks when you report post-filling pain.

4. Different Filling Materials React Differently

Composite (tooth-colored) fillings are bonded to the tooth using a process that can sometimes transmit more sensation initially. They also undergo a slight shrinkage as they cure, which can put microscopic stress on the tooth walls. Amalgam (silver) fillings, which are packed in, can conduct temperature changes more readily, leading to thermal sensitivity. Neither is "better" or "worse" for sensitivity inherently—it's more about technique and the individual tooth's condition.

How Long Should the Sensitivity Last?

Here's the timeline most dentists expect, based on guidelines from authoritative sources like the American Dental Association's patient education materials.

The pulp is resilient. Mild inflammation (reversible pulpitis) typically subsides as the tooth heals. But if the insult was too great, the inflammation can become self-sustaining (irreversible pulpitis), leading to a toothache and potentially needing a root canal. The timeline above helps you gauge which path you're on.

How to Manage and Reduce Sensitivity at Home

You're not just waiting it out. There are concrete actions you can take to soothe the tooth and encourage healing.

Immediate Aftercare (First 3 Days):

• Mind Your Diet: Stick to lukewarm, soft foods. Avoid the extremes: no ice-cold drinks, steaming hot coffee, or hard, crunchy foods. Think yogurt, mashed potatoes, pasta.
• Chew on the Other Side: Give the tooth a complete break from chewing forces.
• Over-the-Counter Pain Relief: Ibuprofen (Advil, Motrin) is often more effective than acetaminophen (Tylenol) for dental pain because it reduces inflammation. Follow the label instructions.
• Gentle Hygiene: Keep the area clean but be gentle. Use a soft-bristled toothbrush and don't aggressively scrub the new filling or the gumline next to it.

Ongoing Care (First Few Weeks):

• Switch to a Desensitizing Toothpaste: This isn't just marketing. Toothpastes with potassium nitrate or stannous fluoride (like Sensodyne or Colgate Sensitive) can actually block the tiny tubules in the dentin, reducing fluid movement and nerve signals. The key is consistency—use it twice a day, and don't rinse with water immediately after; just spit out the excess to let it coat the teeth longer.
• Consider a Fluoride Rinse: An over-the-counter fluoride mouthwash used once a day can help strengthen tooth structure and reduce sensitivity.
• Watch the Acid: Citrus fruits, soda, wine, and sports drinks are acidic and can open up dentin tubules, worsening sensitivity. If you have them, don't brush right after—rinse with water and wait 30 minutes for your enamel to re-harden.

A common mistake: People start brushing the sensitive tooth less because it's uncomfortable. This leads to plaque buildup right at the gumline, which causes gum inflammation and—you guessed it—even more sensitivity. It's a vicious cycle. Gentle, thorough cleaning is non-negotiable.

When Should You Call Your Dentist?

Don't play the hero. Some signs mean the tooth needs professional evaluation, not just more time. Call your dentist if you experience:

• Pain that wakes you up at night. Spontaneous, throbbing pain is a classic sign of a pulp in distress.
• Sensitivity that is severe and not improving after 7-10 days, or is getting worse.
• Pain when you bite down that is sharp and localized to that one tooth, especially if it didn't start until a few days after the filling. This is a prime indicator of a high bite.
• Swelling in your gums near the tooth or in your face.
• A visible crack in the tooth or filling.
• Sensitivity that lasts longer than 3-4 weeks. At this point, it's unlikely to resolve on its own.

What will the dentist do? They'll likely take an X-ray to check the filling's margins and the bone health. They'll test the tooth's vitality with cold and tap on it to check the bite. Most post-filling issues are fixable: a bite adjustment takes two minutes, a replacement filling if the bond failed, or in some cases, a medicated liner under the filling to calm the nerve.