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Why does my tooth hurt when nothing is wrong with it?

A tooth can hurt without being damaged, because its nerves reach the same relay in the brain as those of the sinus, the jaw muscles and even the heart: the brain gets the address wrong. In 6% of people whose heart is short of oxygen, the only pain is in the face (Kreiner, 2007).

Choose where the pain starts: the signal follows its nerve to the relay, then the brain places it on a tooth.

Simplified diagram, not to scale. Pulse of 130 bpm: example value during exercise. The relay measurements come from studies in cats and monkeys.

Why does the brain get the address wrong?

Because far more nerve fibers come in than go out. In the trigeminal relay, at the bottom of the brainstem, a single neuron receives signals from the tooth pulp, the skin of the face, the mouth and the jaw muscles (Sessle, 1986, in cats). The brain receives the message “pain” and places it where it usually finds it: often, a tooth. The heart joins this relay through the vagus nerve, at the top of the spinal cord (Chandler, 1999, in monkeys).

Which tooth, which possible origin?

Where the pain is feltPossible origins outside the toothWhat the studies say
Several upper molarsMaxillary sinus; temporalis muscleRoot of the 2nd molar 1.97 mm from the sinus (Eberhardt, 1992); the temporalis refers pain to the upper molars (Fukuda, 2016)
Lower molarsMasseter muscle; heartThe masseter refers pain to the lower molars (Fukuda, 2016); left and right jaw among the areas most often reported during a heart attack (Kreiner, 2007)
Lower incisorsDigastric muscle, under the chinFukuda, 2016
Jaw, throat and teeth on both sides, during exertionHeartPressure or burning, eased by rest (Kreiner, 2010)
The teeth along one branch, in electric shocksTrigeminal neuralgia55.5% of the people affected had toothache (Tripathi, 2020)
Facial pain in attacksCluster headache34% of 1,163 patients had first seen a dentist (van Vliet, 2003)

Which signs point to the tooth, and which to something else?

Pain triggered by cold, heat or biting on the tooth points to the tooth itself. Pain in several teeth, always the same, that dental treatment and numbing the tooth do not relieve, points to something else (Okeson and Falace, 1997).

What you noticePoints toSource
No pain at rest: it only comes when eating or drinkingThe tooth rather than something else, because pain from elsewhere is often constant; if it fades quickly, the tooth's nerve can still recoverEdwards, 2025; Okeson and Falace, 1997
Pain with cold or sweet that fades in 2 seconds or lessThe tooth: irritated tooth nerve, which can still recoverEdwards, 2025
Pain with heat or cold that lasts more than 30 seconds, or that comes on its own, at rest; later, heat hurts more than coldThe tooth: tooth nerve inflamed for goodEdwards, 2025
Pain when tapping the tooth or biting, on a tooth you can point to with one fingerThe tooth: the tip of the root is affectedEdwards, 2025
Several upper teeth at once, worse when bending the head forward, coughing or sneezing, with a cold or a stuffy noseThe sinusGross and Eliashar, 2008
Dull, spread-out pain that you show with the whole hand rather than one finger; muscles tender when pressed, stiff jawA jaw muscleAbboud, 2026
Electric shocks lasting a fraction of a second to 2 minutes, set off by lightly touching the face, talking or brushing the teeth, but not by heat or coldThe trigeminal nerve (neuralgia)ICHD-3, 2018; Lambru, 2021
On one side only, throbbing for hours or days, with nausea or sensitivity to light and noiseA facial migraineAbboud, 2026
During exertion, eased by rest, on both sides, like pressure or burningThe heart: this is an emergencyKreiner, 2010

No single sign is enough: the sinus, for example, can also hurt more with cold or when a tooth is tapped (Gross and Eliashar, 2008). To sort things out, the dentist combines these signs with cold tests, tapping, and sometimes numbing only the suspect tooth: if the pain remains, it probably comes from elsewhere (Okeson and Falace, 1997), except in neuralgia, which numbing can also relieve (Park, 2012).

Of 88 people referred for a root canal, 3 had no dental problem at all and 8 also had another facial pain. Of 100 people whose facial pain did not come from the teeth, 44 had already had a tooth pulled or a root canal (Linn, 2007).

Does pain that lingers after a root canal come from the tooth?

Not always. After a root canal, about 5 teeth in 100 stay painful (5.3%, Nixdorf, 2010). Among these lingering pains, more than half (44 of 78) came from somewhere other than the tooth: about 3 treated teeth in 100 overall (3.4%, Nixdorf, 2010).

And the other way around, can a diseased tooth affect the rest of the body?

Yes, and here too, the level of evidence depends on the link.

Proven

The sinus. An infected upper tooth can infect the sinus just above it: 25 to 40% of chronic maxillary sinusitis cases, 45 to 75% of sinuses clouded on one side only on a CT scan (Craig, 2022).

Proven, rare but serious

The neck. A dental abscess can spread into the neck. In adults, 40 to 70% of deep neck infections start from a tooth (Maniaci, 2026).

Proven

Bacteria in the blood. In 290 people, bacteria able to infect the heart were found in 23% after toothbrushing and 60% after an extraction without antibiotics (Lockhart, 2008). Mouth streptococci cause 17% of endocarditis cases (Murdoch, 2009). For the American Heart Association, a healthy mouth matters more than antibiotics before dental care (Wilson, 2007 and 2021).

Two-way link

Diabetes. Diabetes damages the gums, and diseased gums make blood sugar harder to control. After gum treatment, HbA1c drops on average by 0.43 points after 3 to 4 months (35 trials, Simpson, 2022).

Association, no proven cause

The heart and arteries. Diseased gums often go with diseased arteries, but smoking, age and diabetes damage both; nothing shows that treating the gums prevents a heart attack (Lockhart, 2012).

Severe gum disease affects more than 1 billion people worldwide (WHO, 2025).

Frequently asked questions about toothache from elsewhere

Can sinusitis cause toothache?

Yes. The roots of the upper molars are very close to the sinus, 1.97 mm on average for the 2nd molar (Eberhardt, 1992), and their nerves follow the same branch. Sinusitis can therefore be felt in several upper teeth at once.

Can jaw pain come from the heart?

Yes. During a heart attack, 4 patients in 10 have pain in the face, throat or jaw (Kreiner, 2020), and for 6% it is the only pain (Kreiner, 2007). It often comes with exertion, on both sides, like pressure. This is an emergency.

Why do teeth hurt on a plane or when diving?

The change in pressure can trigger tooth pain: this is barodontalgia. A review of 4,894 pilots, aircrew and divers found it in 8.2% of them (Nakdimon and Zadik, 2019).

Does pulling the tooth make the pain go away?

Not if the pain comes from elsewhere. In trigeminal neuralgia, the people surveyed had lost on average 1.6 teeth pulled without the pain going away (Tripathi, 2020).

With care: this site explains, it does not replace medical or dental advice. Pain in the jaw, throat or teeth that comes on with exertion, with tightness in the chest, shortness of breath, sweating or feeling faint, may come from the heart: this is an emergency, call 911 or your local emergency number.

See also

The vagus nerve A synapse in motion Motion sickness

Sources

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True or false?

Sinusitis can make your upper teeth hurt.

True. The root of the upper 2nd molar is on average 1.97 mm from the sinus, and both follow the same nerve (Eberhardt, 1992).

A heart attack always causes chest pain.

False. In 11 of 186 people whose heart was short of oxygen, the only pain was in the face, throat or jaw (Kreiner, 2007).

Pressing on a muscle can trigger pain somewhere else.

True. In 196 of 230 people with a jaw disorder, pressing on the muscles made them feel pain somewhere else (Wright, 2000).

The steps as text

The texts shown during the animation, to read without it.

Other texts from the animation

  • Decay reaches the pulp, the living core of the tooth, full of tiny nerves. They send a pain signal.
  • The signal leaves through the mandibular nerve, the lower branch of the trigeminal nerve. The upper teeth use another branch, the maxillary nerve.
  • In the brainstem, the signal reaches the trigeminal relay. This is where fibers from the teeth, the facial skin, the muscles and the sinuses meet.
  • Here, no mistake: the brain places the pain on the right tooth. A throbbing pain is more likely to point to a tooth (Kreiner, 2010).
  • The maxillary sinus, an air pocket just above the upper teeth, is inflamed. Its lining swells and irritates its nerves.
  • Its nerves follow the same branch as those of the upper teeth: the maxillary nerve. The root of the 2nd molar is only 1.97 mm from the sinus on average (Eberhardt, 1992).
  • At the relay, the sinus fiber and the tooth fiber reach the same neurons. The neuron passes on “pain” without saying where it comes from.
  • The brain, used to messages from the teeth, places the pain on several upper molars at once. The teeth are fine: it is the sinus.
  • The masseter, the muscle that closes the jaw, is tight and sore. A hard knot forms in it, tender when pressed.
  • Its signal follows the mandibular nerve, like that of the lower teeth.
  • At the relay, fibers from the jaw muscles, the teeth and the facial skin reach the same neurons (Sessle, 1986, in cats).
  • The pain is felt in the lower molars. The temporalis, the muscle of the temple, refers it instead to the upper molars (Fukuda, 2016). Of 230 people with a jaw disorder, 196 felt pain elsewhere when their muscles were pressed (Wright, 2000).
  • During exertion, the heart beats fast and runs short of oxygen: this is angina, or a heart attack. Its nerves send a pain signal.
  • Part of the signal travels up the vagus nerve to the top of the spinal cord, in the neck, at the level of the first 2 vertebrae (Foreman, 2015).
  • There, fibers from the vagus nerve and from the face mix on the same neurons, according to measurements in monkeys (Chandler, 1999). The brain can no longer tell whether the message comes from the heart or from the jaw.
  • The pain is felt in the jaw, throat or teeth, often on both sides, during exertion, and it eases at rest (Kreiner, 2010). Of 186 people whose heart was short of oxygen, 11 had pain only in the face (Kreiner, 2007).
  • This time, nothing comes from an organ: the trigeminal nerve itself misfires and sends out shocks. This is trigeminal neuralgia.
  • The shocks run along a whole branch, the upper or the lower one.
  • The relay receives a very strong signal, as if all the teeth on that branch hurt at the same time.
  • The brain places the pain in the teeth. Of 117 people affected, 55.5% had toothache and 19.6% had had a root canal (Tripathi, 2020).
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Metabolive. "Why does my tooth hurt with no cavity?" Updated November 8, 2026. https://metabolive.com/en/brain/toothache-no-cavity.