A tooth that hurts when you bite down is one of the most common reasons people call us. Most assume it’s cracked. Sometimes it is. But a crack is only one of several things that can make a tooth sore to chew on, and they don’t all have the same answer.
The short answer: pain on biting can come from a filling or crown that sits a little high, a bite that has shifted, an infected tooth, a crack, the gums around the tooth, or even your sinuses. Telling them apart usually takes an exam and a few simple tests. And sometimes the honest answer is that we need more information, or that the tooth needs a little time.
The usual causes
A filling or crown that sits a little high
If one spot on a new filling or crown hits before everything else, that tooth takes the whole force of your bite and gets sore. It doesn’t take much. In a small study, fillings made just a fraction of a millimeter too high made teeth tender, and the soreness went away once the bite was adjusted. If a tooth started hurting soon after new work, this is the first thing we check.
Ikeda T, et al. The effect of light premature occlusal contact on tooth pain threshold in humans. J Oral Rehabil. 1998;25(8):589-595. Clark GT, et al. Sixty-eight years of experimental occlusal interference studies: what have we learned? J Prosthet Dent. 1999;82(6):704-713.
A bite that has changed
Your bite isn’t fixed. The jaw joint and the jaw muscles decide where your lower jaw sits when your teeth come together, and when they change, so does the bite. We’ve even seen the neck and shoulder muscles shift it enough that teeth that used to fit point into groove start meeting point to point. Usually this happens gradually, but it can be sudden, and the tooth that now hits first is the one that hurts.
This is also one reason we don’t do same-day crowns. A bite can shift between the day a tooth is prepared and the day the crown goes on, and a few weeks in a temporary lets the muscles settle first.
Makofsky HW, et al. The effect of head posture on muscle contact position using the T-Scan system of occlusal analysis. Cranio. 1991;9(4):316-321. In that small study, head and neck posture changed where the teeth first touched in people over 30. Kang MG, et al. Clinical characteristics of temporomandibular disorders presenting posterior open bite. J Dent Sci. 2021;16(3):861-867.
An infected tooth
When the nerve inside a tooth is inflamed or has died, the tissue around the root tip gets inflamed too, and biting on the tooth hurts. An abscess at the root can even push the tooth up slightly, so it hits before its neighbors and hurts more with every bite. In one study of patients with an inflamed nerve, more than half had pain on biting or pressure. The other signs that point to a problem inside the tooth.
Owatz CB, et al. The incidence of mechanical allodynia in patients with irreversible pulpitis. J Endod. 2007;33(5):552-556. Chia MS, et al. Severe extrusion from an apical abscess: a case report. Dent Update. 2004;31(10):602-607.
A crack
Not every line in a tooth is a crack. A craze line is a fine line in the outer enamel, it’s common as teeth age, and it usually needs nothing. A dark crack is different. It’s dark because it’s open to your mouth and stain has worked into it, which means it’s opening and closing a tiny bit every time you bite. That tooth is already cracked.
Cracks don’t always hurt, and the dark ones were less likely to hurt in a large study of US practices. When they do, the classic complaint is a sharp pain on one spot when you bite, or when you let go. Cold sensitivity is actually more common than biting pain.
Most cracked teeth don’t split. In that same national study, about 3% of cracked teeth broke over three years. But any of them can, on something as ordinary as a nut, and a crack that runs all the way down can cost the tooth. So the conversation isn’t “this tooth will break.” It’s “if it does, you could lose it. Are you prepared for that?” Some people would rather protect the tooth now, and some would rather wait. Both are reasonable once you know what you’re choosing between. Why a crack that doesn’t hurt can still matter.
Hilton TJ, et al. Correlation between symptoms and external characteristics of cracked teeth. J Am Dent Assoc. 2017;148(4):246-256. Ferracane JL, et al. Observable characteristics coincident with internal cracks in teeth. J Am Dent Assoc. 2018;149(10):885-892. Hilton TJ, et al. Baseline characteristics as 3-year predictors of tooth fracture and crack progression. J Am Dent Assoc. 2021;152(2):146-156. Findings from the National Dental Practice-Based Research Network.
The gums around the tooth
A gum abscess, a pocket of infection beside the tooth, makes it tender to bite on and usually comes with swelling and bleeding. It needs to be seen promptly. Food packed between two teeth can do a milder version of the same thing.
Herrera D, et al. Acute periodontal lesions (periodontal abscesses and necrotizing periodontal diseases) and endo-periodontal lesions. J Clin Periodontol. 2018;45 Suppl 20:S78-S94.
Your sinuses
The roots of the upper back teeth sit right under the sinus. A sinus infection can make those teeth ache and feel sore to bite on, even when the teeth themselves are fine. It works the other way too: an infected upper tooth can cause a sinus infection.
Ferguson M. Rhinosinusitis in oral medicine and dentistry. Aust Dent J. 2014;59(3):289-295.
Clenching and grinding
Teeth that are sore when you wake up can point to grinding or clenching at night. Why it’s rarely just stress, and what helps.
How we sort it out
We usually work through four tests, and each one points somewhere different.
- The bite stick. You bite on a small tip (a Tooth Slooth) placed on one cusp at a time. If one spot hurts, especially when you let go, that points to a crack in that part of the tooth. In one study it reproduced the pain in about 9 out of 10 cracked teeth.
- Cold. We compare the tooth with its neighbors. How the nerve responds tells us whether it’s healthy, irritated, or no longer alive.
- Tapping. A tooth that’s sore to tap usually has irritation around the root, from an infection at the root tip or from taking too much of the bite.
- X-rays. They show infection at the root tip, decay and the bone. They rarely show a crack: in the national study, only 1 to 4% of cracks were visible. A normal X-ray doesn’t rule one out.
Yang Y, et al. Biting pain reproduced by the Tooth Slooth: an aid for early diagnosis of cracked tooth. Quintessence Int. 2019;50(1):82-87. Hilton TJ, et al. Recommended treatment of cracked teeth. J Prosthet Dent. 2020;123(1):71-78.
When the tests don’t add up
If the bite stick, cold, tapping and X-rays all come back vague, the tooth may be fine and the bite around it may have changed. That’s when we look at the muscles: the jaw muscles, and sometimes the neck and shoulders. When the muscles are the cause, the answer is usually a mix of things rather than one fix, and we often recommend a 3D scan (CBCT) to rule out a problem in the jaw joint itself. How we treat jaw muscle and joint problems.
And sometimes the honest answer is that we need more information, or that the tooth just needs time, especially when the bite or the muscles are behind it. A tooth that hurts on the bite stick is a different story. In our experience, those don’t get better on their own.
If it turns out to be a crack that hurts
We probe the gum around the tooth. A deep, narrow pocket right where the crack is usually means the root has split, and a split root can’t be saved. If there’s no deep pocket, the tooth goes to an endodontist to evaluate. Research agrees that the deeper the pocket at the crack, the worse a cracked tooth does after a root canal.
Either way it’s your decision. If you’d rather have the tooth out than try to save it, that’s an option too. How to weigh saving a tooth against taking it out.
Olivieri JG, et al. Outcome and survival of endodontically treated cracked posterior permanent teeth: a systematic review and meta-analysis. J Endod. 2020;46(4):455-463. Wongkornchaowalit N, et al. Treatment outcomes and prognostic analysis of root canal-treated posterior cracked teeth. J Endod. 2026;52(1):79-88.
When it can’t wait
Call us the same day if the tooth hurts and you have swelling. If the swelling is spreading toward your eye or into your neck, if you have trouble swallowing or breathing, or a fever along with the swelling, go to a hospital emergency room. Our emergency page explains why.
Where to start
If a tooth hurts when you bite, call 702-734-0776. Tell us when it started, whether you’ve had any recent dental work, and whether it hurts when you bite down, when you let go, or both. That alone narrows it down.
General education, and not a substitute for an exam.