If you’ve been wondering why your teeth hurt, here’s the short answer: tooth pain almost always means something specific is going on — and most causes are very treatable when caught early. Below are the eight most common culprits, what each one feels like, and what you should actually do about it.
1. You Have a Cavity
A cavity starts as a tiny patch of tooth decay, but as it grows it gets closer to the nerve inside your tooth. That’s when you start to notice it. Early cavities may only ache when you eat something sweet or cold. Deeper ones can throb on their own.
Tooth decay is the most common chronic disease in the world, according to the World Health Organization. The good news: a cavity caught early needs only a straightforward dental filling in South San Francisco. A cavity ignored for months may need a root canal or even extraction instead. Don’t wait.
What it feels like: Sharp pain when biting, lingering sensitivity to sweet foods, or a visible dark spot on the tooth.
2. Tooth Sensitivity
You reach for your morning coffee or bite into something cold, and a quick, sharp jab shoots through one or more teeth. That’s classic tooth sensitivity. It happens when enamel wears down or gums recede, exposing the dentin layer underneath. Dentin has thousands of microscopic channels that lead straight to the nerve.
Common triggers include acidic foods and drinks, aggressive brushing with a hard-bristled toothbrush, tooth-whitening overuse, and acid reflux. Desensitizing toothpastes containing potassium nitrate or stannous fluoride can help mild cases. Persistent sensitivity deserves a dental evaluation because it can signal a deeper problem.
What it feels like: Brief, sharp pain triggered by hot, cold, sweet, or acidic foods — not a constant ache.
3. A Cracked or Fractured Tooth
Cracked teeth are sneaky. You might not see anything wrong, but you feel a sharp pain when you bite down on something and then it disappears almost immediately. That on-off pattern is a hallmark of a cracked tooth.
Cracks happen from chewing hard foods (ice, popcorn kernels, hard candy), old large fillings that weaken the surrounding tooth structure, or taking a hit to the face. Small cracks can often be repaired with bonding or a crown. A crack that reaches the root is a bigger deal and may require extraction.
What it feels like: Sharp pain when biting or chewing that disappears quickly; sometimes sensitivity to temperature.
4. Gum Disease
Gum disease — in its milder form called gingivitis and its more advanced form periodontitis — is painless in the early stages, which is exactly why so many people miss it. By the time it starts to ache, bone loss is often already underway. Pain from gum disease tends to be dull and persistent, sometimes spreading across a whole quadrant of your mouth.
The CDC reports that nearly half of American adults over 30 have some form of periodontitis. Treatment ranges from a professional deep cleaning (scaling and root planing in South San Francisco) to more involved periodontal therapy for advanced disease. Regular cleanings are the single best prevention.
What it feels like: Dull, persistent aching; tender, bleeding, or swollen gums; teeth that feel loose.
5. Teeth Grinding (Bruxism)
A lot of people grind their teeth at night and don’t realize it until their dentist notices the wear patterns. But your body might be giving you hints: dull morning headaches, jaw soreness, and teeth that ache all day without an obvious cause are all classic signs.
Bruxism puts enormous forces on teeth — up to 10 times the pressure of normal chewing — and can crack teeth, wear down enamel, and inflame the jaw joint over time. A custom-fitted dental night guard is the standard protective treatment. It won’t stop the grinding, but it distributes the force and keeps teeth from destroying each other.
What it feels like: Generalized aching across multiple teeth, jaw tightness, or morning headaches rather than pain in one specific spot.
6. An Abscess or Tooth Infection
This is the one you should not sit on. A dental abscess is a pocket of infection, usually at the root tip or in the gum beside a tooth. Left untreated, it can spread to the jaw, neck, or — in rare but serious cases — to other parts of the body.
The pain of an abscess is hard to ignore: it’s severe, often throbbing and constant, and can wake you up at night. You might notice swelling in the gum or jaw, a foul taste in your mouth, or a small pimple-like bump on the gum. This is a dental emergency. Call our office right away or seek same-day care.
What it feels like: Severe throbbing pain, sometimes with swelling, fever, or a bad taste; doesn’t go away on its own.
7. A Damaged or Failing Filling
Old fillings don’t last forever. Over years of chewing, they can crack, chip, or pull away from the tooth. When they do, bacteria sneak into the gap and a new cavity can start right underneath the old repair. You’ll often notice increased sensitivity in a tooth that “used to be fine.”
This is one of the reasons regular exams matter so much. Our team checks the integrity of existing restorations at every visit, so small failures get caught before they become expensive problems. A failing filling is usually an easy fix — until it isn’t.
What it feels like: New sensitivity in a previously treated tooth; you may feel a rough edge or notice a piece has chipped off.
8. Sinus Pressure
Here’s one that surprises people: your upper back teeth sit very close to your sinus cavities. When your sinuses are inflamed — from allergies, a cold, or a sinus infection — the pressure presses directly on the roots of those teeth. The result is a dull, heavy ache that often affects several upper teeth at once.
The key giveaway is that the pain affects multiple teeth symmetrically and gets worse when you lean forward or bend over. It usually improves as the sinus congestion clears. If you’re not sure whether it’s your sinuses or a dental issue, a quick exam can rule out a cavity or abscess quickly.
What it feels like: Dull, pressure-like ache in the upper back teeth; often on both sides; tied to congestion or seasonal allergies.
The Bottom Line
Tooth pain is your mouth’s way of flagging a problem, and most causes get easier and cheaper to fix the sooner you act. Cavities, gum disease, cracked teeth, abscesses — none of them resolve on their own, and waiting typically turns a small fix into a bigger one. If your teeth have been bothering you — whether it’s a sharp jolt or a dull background ache — it’s worth getting it checked.
Our team in South San Francisco sees these issues every day, and figuring out exactly what’s causing your pain is the first step to making it stop.
Frequently Asked Questions
Can tooth pain go away on its own?
Occasionally, very mild sensitivity eases up if the trigger (like a whitening product) is removed. But pain from a cavity, crack, abscess, or gum disease will not resolve without treatment. If pain disappears suddenly after being severe, that can actually mean the nerve has died — which still needs treatment. When in doubt, get it checked.
What’s the difference between a toothache and jaw pain?
Toothache pain usually traces to a specific tooth or area — it’s often triggered by biting or temperature. Jaw pain tends to be more diffuse, involves the muscles or joint, and may be linked to grinding or TMJ issues. The two can overlap, which is why a professional exam is the most reliable way to sort them out.
When is tooth pain a dental emergency?
Seek same-day care if you have severe throbbing pain that doesn’t let up, visible swelling in the gum or face, a fever, or difficulty swallowing or breathing. Those are signs of a spreading infection and should not wait for a routine appointment.
How do dentists figure out which tooth is causing the pain?
A few clinical tools help narrow it down: percussion testing (gently tapping each tooth), cold and bite tests to check for cracks or nerve involvement, and X-rays to check for decay, infection, or bone loss. At our office, our team uses digital dental X-rays in South San Francisco, reviewed with Pearl AI, an FDA-cleared system that helps flag early problems that can be easy to miss on a standard read — so you get a thorough look, not just a quick scan.
Ready to stop guessing what’s causing your tooth pain?
Written by the Vaksman Dental Group team and medically reviewed by Dr. Irena Vaksman, DDS — South San Francisco. Last reviewed July 2026.