My tooth hurts but the X-ray looks normal. Why, and what happens next?

What an X-ray shows, and what it cannot

A dental X-ray is a shadow picture of hard tissue. It shows the enamel and dentin of the tooth, the bone around the root, the outline of fillings and crowns, and changes that have been present long enough to alter the density of bone, such as decay between teeth or an abscess that has dissolved bone at the root tip.

What the X-ray does not show is soft tissue. The pulp (the nerve and blood vessels inside the tooth) appears only as a dark space; the X-ray cannot say whether that nerve is healthy, inflamed or dying. The ligament that holds the tooth in its socket, the gum, the chewing muscles and the jaw joint are not pictured in any useful detail. A hairline crack is usually too fine, and often runs at the wrong angle to the beam, to appear as a line. Early inflammation at a root tip may not yet have changed enough bone to cast a shadow.

So a "normal" X-ray rules out some causes and leaves others fully open. Professional guidance treats X-rays as an adjunct ordered after the history and clinical examination, chosen to answer a specific question, not as a stand-alone test. The guide on whether X-rays are needed at every check-up explains how that choice is made when nothing hurts.

Why a different view or a 3D scan is sometimes added

Two-dimensional X-rays flatten a three-dimensional tooth, so a root tip or a crack can hide behind another structure, and a second X-ray from a different angle occasionally shows what the first missed. A 3D X-ray, usually a cone-beam CT scan (the practice lists digital and 3D X-rays among its check-up services), shows the roots and surrounding bone in slices rather than flattened onto one image, so details that overlap on a flat X-ray can be seen. It is not added routinely. Guidance reserves it for questions that conventional X-rays cannot answer, because it delivers a higher radiation dose, and it still does not image the nerve inside the tooth or a crack that has not separated. Whether a 3D scan would help is decided after the clinical tests below.

The tests the X-ray cannot replace

When the picture is clean and the tooth still hurts, the dentist's job is to reproduce your pain in the chair, because the test that brings on your exact symptom usually points to the cause. Expect some or all of the following, done on the suspect tooth and on its neighbors for comparison:

• Cold test. A cold-soaked pellet or spray is touched to each tooth. A healthy nerve feels a brief sharp sensation that fades within seconds. A response that lingers well after the cold is removed suggests an inflamed nerve. No response, when neighboring teeth respond normally, can suggest the nerve has died. The guide on lingering cold sensitivity covers what to report.
• Percussion (tapping). Tapping gently on each tooth tests the ligament around the root. Tenderness with a normal X-ray can mean inflammation spreading from the nerve, a ligament bruised by a high bite contact or grinding, or a crack.
• Bite test on individual cusps. You bite on a small instrument placed on one cusp at a time. A sharp pain on biting, and especially on letting go, is the classic clue to a crack no X-ray has shown. The guide on sharp pain when you release your bite explains that clue in detail.
• Gum measurements. A thin probe measures the depth of the groove between tooth and gum. A deep, narrow pocket beside one root can mean a gum abscess, a crack extending down the root or periodontal disease, any of which can ache before the X-ray changes.
• Bite and muscle check. The dentist looks at how the teeth meet, checks for a filling or crown that touches first, and presses on the chewing muscles and jaw joint. A sore muscle that reproduces your "toothache" points away from the tooth.
• Magnification, dye and light. Staining a suspect area, shining a bright light through the tooth, or removing an old filling to look underneath can show a crack line directly.

If pain comes only when you chew, the guide on why one tooth hurts when you bite walks through the biting patterns.

The cause-and-clue table

When the pain comes from outside the tooth

The roots of the upper back teeth sit just below the floor of the maxillary sinus. When the sinus lining is inflamed, as in a cold or sinusitis, pressure there can be felt as a toothache in several upper teeth at once, often with facial tenderness and congestion. The teeth test normally, and a physician may be involved if it persists.

Pain from the jaw joint and the chewing muscles can radiate into the face, jaw and neck, sometimes as a toothache, and may come with jaw stiffness, clicking or a changed bite. For most people this kind of pain is temporary and is managed with conservative, reversible measures first. If you wake with a sore jaw, the guide on morning jaw soreness and grinding describes what an examination looks for.

Teeth also share nerve pathways, so the brain can mislocate the source: an inflamed lower molar can be felt as an upper toothache, and a problem on one tooth can be felt on its neighbor. That is why the tests are repeated across the whole area, and why the X-ray of the tooth you point to can look perfect while the culprit is next door.

Occasionally no dental test reproduces the pain at all. Toothache-like pain can come from the ear, the sinuses or the jaw joint and muscles, and jaw or tooth pain is among the less common presentations of a heart attack. When the dental examination is negative, a referral to your physician is the sensible next step, and treatment on a tooth that has not been shown to be the cause is usually avoided.

What "wait and re-test" means

When the tests are inconclusive, or point to mild inflammation that may settle, observation is often better than immediate treatment. The plan usually includes adjusting a high spot if one is found, avoiding hard chewing on the tooth, keeping a short pain diary, and returning in a few weeks to repeat the cold, tapping and bite tests, sometimes with a new X-ray. Nerve inflammation can calm down on its own, and if it does not, the pattern usually becomes clearer with time, which helps avoid a root canal or an extraction on the wrong tooth.

If a crack is found, how it is managed depends on its location, direction and depth; options range from bonding to covering the tooth, and in some cases root canal treatment, so ask the dentist to explain the reasoning. Return earlier than planned if pain starts to linger, begins on its own, wakes you, or any swelling appears.

When to go to emergency care instead

Some symptoms should not wait for a dental appointment or an online request. Call 911 or go to the nearest emergency department if tooth or jaw pain comes with any difficulty breathing or swallowing, swelling spreading quickly across the face or down the neck, fever together with facial swelling, bleeding you cannot control, or a serious injury to the face or jaw. Jaw or tooth pain together with chest pressure, shortness of breath, sweating or nausea should be treated as a possible heart emergency.

What to write down before the visit

• Where it hurts. Can you point to one tooth, or is it an area, a side or the whole jaw?
• What sets it off. Cold, heat, sweet, biting down, letting go, chewing, bending forward, first thing in the morning, or nothing at all.
• How long it lasts. Seconds, minutes or hours, and whether it ever starts on its own or wakes you.
• What has changed recently. New dental work, an injury, a cold or sinus symptoms, a stressful period, a new clenching habit.
• Previous X-rays. Ask your prior office to send them so the dentist can compare rather than start from zero.

The next step

If your tooth hurts and a recent X-ray was normal, that is exactly the situation a careful examination is for. You can request an appointment online or call the office during business hours, and say that you are in pain and that an X-ray has already been taken, so the visit can be planned around the tests above.