Pain in a capped (crowned) tooth usually signals that something is going on beneath or around the restoration, not that the crown itself is the problem. The crown is a shell; beneath it sits tooth structure, possibly a living nerve, surrounding gum tissue, and bone, any of which can become irritated, infected, or damaged long after the crown was placed. Figuring out what to do starts with narrowing down the cause, and the possibilities range from a simple bite adjustment to retreatment of the root canal inside.
The Nerve May Still Be Alive and Unhappy
If your crown was placed over a tooth that never had a root canal, the nerve (pulp) is still inside. That living tissue can become inflamed for several reasons: the original cavity may have been deep enough that the preparation and cementing process irritated the nerve, or new decay may have crept under the crown margin over time. Either way, the nerve swells inside a rigid space with no room to expand, and the pressure turns into pain. Early on, the discomfort tends to be brief and triggered by hot or cold drinks. If the inflammation progresses, the pain becomes spontaneous, throbbing, and may wake you at night.
Stress on the tooth itself matters too. Finite element research on crowned teeth shows that mechanical stress concentrates around the neck of the tooth, right where the crown meets the root, regardless of which crown material is used.1Heliyon. Evaluation of stress distribution on an endodontically treated maxillary central tooth with lesion restored with different crown materials: A finite element analysis That repeated stress can aggravate an already inflamed nerve or contribute to micro-cracks that let bacteria reach the pulp. If pulp inflammation is caught early (what dentists call reversible pulpitis), the tooth may settle down on its own or with a bite adjustment. If it progresses to irreversible pulpitis or outright infection, a root canal through the existing crown becomes the likely treatment.
Decay Can Form Under the Crown
A crown does not make a tooth immune to cavities. The junction where the crown edge meets the natural tooth is a seam, and over the years cement can wash out, margins can gap, and bacteria can colonize the space underneath. Because the crown hides everything, decay can grow unchecked until it reaches the nerve or weakens the tooth structure enough to cause pain. The discomfort often starts as sensitivity to sweets or cold and escalates.
This is one reason your dentist takes X-rays of crowned teeth at check-ups. Decay under a crown is harder to spot on a radiograph because the metal or ceramic obscures the image, but large areas of breakdown usually show. If the decay is modest, the crown can sometimes be removed, the decay cleaned out, and a new crown made. If the decay has reached the nerve, a root canal is needed first.
A Bite That Doesn’t Sit Right
When a new crown is slightly too high, it hits the opposing tooth before the rest of your bite closes, absorbing a disproportionate share of chewing force. That concentrated pressure bruises the ligament that suspends the tooth in bone, producing a dull ache that worsens when you chew. Even a fraction of a millimeter matters. Research on how prosthetic teeth interact with opposing natural teeth confirms that a rigid restoration can exert force dominance on the opposing side, potentially damaging the supporting tissues of both the crowned tooth and the tooth it bites against.2CrossRef API / Actual problems in dentistry. FEATURES OF PERCEPTION OF CHEWING PRESSURE IN FUNCTIONAL OCCLUSION IN PERSONS WITH DEFECTS OF DENTAL ROWS IN PROSTHETIC TREATMENT WITH DENTAL IMPLANTS
If your pain started within days of getting the crown and feels worst when you clench or chew on that side, a high bite is a strong possibility. The fix is straightforward: your dentist marks the bite with articulating paper and carefully adjusts the crown surface until your teeth meet evenly. Relief is often immediate. If the crown has been in place for years and the bite was fine before, a new high spot can develop if you lose a tooth elsewhere or if grinding habits shift your jaw position over time.
Gum Inflammation Around the Crown
A crown margin that sits too far below the gum line or too close to the underlying bone can violate what dentists call the biological width, the natural seal of gum and connective tissue that attaches to the root. When that seal is disrupted, the body responds with chronic inflammation. The result is red, swollen, sometimes tender gums right around the crowned tooth, persistent bleeding when brushing, and in some cases localized bone loss.3KnE Medicine. Crown Lengthening for Obtaining Biological Width in Dental Restoration: A Case Report Research specifically on biological width violations links them to gingival inflammation, alveolar bone loss, and poor restoration fit.4European Journal of General Dentistry. Biological width: No violation zone
The pain from this kind of problem is usually a low-grade soreness rather than sharp toothache. You might notice a bad taste or smell localized to that tooth. Treatment depends on severity: sometimes a new crown with better-placed margins is enough, but if bone has been lost, a minor surgical procedure called crown lengthening may be needed to re-establish proper clearance before re-restoring the tooth.
Poor oral hygiene around the crown can cause gum problems even when the margins are well placed. Plaque builds up at the gum line just as it does on natural teeth, and crowned teeth can be harder to floss around. People who clean between their teeth regularly are less likely to develop decay and gum disease around restorations.5J Am Dent Assoc. J Am Dent Assoc. 2018 Nov;149(11):e146.
Cracks and Root Fractures
A tooth that has been heavily restored, especially one with a large filling under the crown or a previous root canal, is structurally weaker than an intact tooth. Over years of chewing and clenching, cracks can develop in the root. A cracked tooth typically produces sharp, fleeting pain when you bite down on something hard and release, because the crack flexes open momentarily. A full vertical root fracture (VRF) is more serious: the crack extends along the root, and bacteria colonize the fracture line, causing a localized infection that mimics a gum pocket.
Distinguishing between a crack and a fracture matters because the treatments are completely different. Research using cone-beam CT imaging found that teeth with vertical root fractures were more commonly associated with indirect restorations (like crowns), deep probing pockets greater than 6 mm, and a characteristic J-shaped bone defect on the scan. Cracked teeth, by contrast, tended to have shallow probing and a different pattern of bone change.6PubMed. CBCT Patterns of Bone Loss and Clinical Predictors for the Diagnosis of Cracked Teeth and Teeth with Vertical Root Fracture A cracked tooth can sometimes be saved with a new crown or root canal treatment. A vertically fractured root, unfortunately, usually means extraction.
When the Tooth Looks Fine but Still Hurts
Sometimes every test comes back normal, the X-rays are clean, the gums look healthy, the bite seems balanced, and yet the tooth aches. One recognized explanation is a condition known as atypical odontalgia, sometimes called phantom tooth pain. It is a persistent pain in or around a tooth (or tooth socket) that continues after dental treatment despite no identifiable cause on clinical or radiographic examination.7Journal of Nepalese Prosthodontic Society. Atypical Odontalgia or Phantom Tooth Pain: Current Evidences for Better Understanding, Diagnosis and Management It is thought to involve nerve signaling gone awry, where the peripheral nerves continue sending pain messages even after the original cause has been resolved.
Atypical odontalgia is a diagnosis of exclusion, meaning your dentist needs to rule out every structural cause first. It matters because pursuing more dental procedures on a tooth with phantom pain tends to make things worse, not better. Treatment usually involves low-dose medications that calm nerve signaling rather than further drilling or extraction. If you have had multiple procedures on a crowned tooth and the pain persists unchanged each time, raising this possibility with your dentist or asking for a referral to an orofacial pain specialist is worth considering.
Referred pain from somewhere else entirely can also masquerade as a toothache. Sinus infections famously cause upper-back-tooth pain because the roots sit close to the sinus floor. Jaw joint disorders, ear infections, and even tension headaches can radiate pain to the teeth. If your dentist cannot find anything wrong with the crowned tooth, these possibilities should be explored.
Reactions to Crown Materials
Most modern crowns are made of porcelain, zirconia, or porcelain fused to metal, and adverse reactions to these materials are uncommon. But they are not zero. A systematic review of allergic reactions to dental materials found that while amalgam was the most frequently reported culprit for oral reactions, other metals used in dental restorations, including nickel, cobalt, and chromium found in some metal alloys, can also trigger contact reactions in susceptible people.8PubMed Central. Allergic Reactions to Dental Materials-A Systematic Review Symptoms of a metal allergy in the mouth can include persistent burning, redness, or soreness of the gum tissue directly adjacent to the crown.
A related phenomenon is oral galvanism, which can occur when two different metals are present in the mouth, for instance a gold crown on one tooth and a metal-ceramic crown with a different alloy nearby. The saliva acts as a weak electrolyte, and a tiny electrical current flows between the dissimilar metals. Reported symptoms include a metallic taste, burning sensations on the tongue or gums, and in some cases pain in the affected teeth.9PubMed Central. Oral galvanism related to dental implants Oral galvanism is not common, but if your symptoms appeared after a new metal restoration was placed alongside existing metalwork, it is worth mentioning to your dentist.
How Your Dentist Tracks Down the Cause
Diagnosing a problem under a crown is trickier than diagnosing the same issue on an unrestored tooth. The crown blocks direct visualization, muffles temperature testing, and can interfere with electrical pulp testing. A clinical study on the accuracy of pulp tests on crowned teeth concluded that both electric pulp testing and cold testing should be considered supplementary tools, with results interpreted alongside other clinical signs and symptoms rather than taken at face value.10PubMed Central. The Validity of Pulp Tests on Crowned Teeth: A Clinical Study
Your dentist will likely combine several methods:
- Bite test: biting on a stick or rubber instrument to see if pressure or release reproduces the pain, which helps distinguish a cracked tooth from a high bite.
- Periodontal probing: measuring the gum pocket depth around the crown. A single deep pocket on one side of the tooth can point toward a root fracture or localized infection.
- X-rays or CBCT scan: a standard X-ray can reveal large areas of decay, an abscess, or bone loss. A cone-beam CT scan provides three-dimensional detail and is especially useful for spotting root fractures and the specific bone-loss patterns associated with them.6PubMed. CBCT Patterns of Bone Loss and Clinical Predictors for the Diagnosis of Cracked Teeth and Teeth with Vertical Root Fracture
- Thermal and electric testing: applying cold or a small electrical stimulus to check whether the nerve inside is still responsive. A tooth that doesn’t respond at all may have a dead or dying nerve.
Be as specific as you can when describing the pain. Whether it is sharp or dull, constant or triggered, worsened by heat or cold, localized to the crown or radiating elsewhere, all of these details help your dentist narrow the differential faster.
What Treatment Looks Like
Treatment depends entirely on the diagnosis, but a few scenarios come up repeatedly with crowned teeth.
If the nerve is inflamed or infected, a root canal can usually be done through the existing crown. The dentist drills an access hole through the top of the crown, completes the root canal, and then fills the hole. Research on endodontic retreatment through crown access reports a success rate around 91%, making it the preferred first-line approach over surgical alternatives.11Key Engineering Materials. The Efficiency of Endodontic Retreatment through Direct Crown Access One concern patients have is whether drilling through the crown weakens it. Lab testing has shown that an access hole left unfilled does reduce how well the crown grips the tooth, but restoring the hole with composite or amalgam actually brings the retention back to or above the original level.12PubMed. In Vitro Comparison of Porcelain Fused to Metal Crown Retention after Endodontic Access and Subsequent Restoration: Composite, Amalgam, Amalgam with Composite Veneer, and Fiber Post with Composite So in most cases, the crown does not need to be replaced just because a root canal was performed through it.
If a high bite is the culprit, a simple occlusal adjustment at the dental office, usually a five-minute visit, resolves the problem. If gum inflammation from a poorly fitting margin is driving the pain, the options range from replacing the crown with better-fitting margins to crown lengthening surgery if the biological width has been violated. For decay under the crown, the crown comes off, the decay is removed, and a new restoration is planned once the tooth is sound again.
Root fractures are the hardest diagnosis and the least hopeful. If a vertical root fracture is confirmed, extraction is typically the only realistic option, followed by an implant, bridge, or other replacement. Cracked teeth without a full fracture line may be salvageable with a new crown or root canal, depending on how deep the crack extends.
Keeping Crowned Teeth Out of Trouble
You can reduce the odds of future problems with a few habits. Floss or use an interdental brush around every crowned tooth daily, paying special attention to the gum line where the crown meets the tooth. If you grind your teeth at night, wearing a night guard protects both your crowns and the opposing teeth from excessive force. Avoid using crowned teeth to crack ice, tear open packaging, or chew on hard objects like pen caps, all of which dramatically increase the risk of fracture.
Regular dental check-ups matter more with crowns than without them, precisely because problems underneath are invisible until they become advanced. A crown placed ten or fifteen years ago may still look perfect from the outside but have cement washout, margin gaps, or early decay forming out of sight. Catching these issues early with periodic X-rays and probing is far less invasive and less expensive than dealing with the consequences once pain develops.
Phantom Pain and the Temptation to Keep Treating
One pattern worth knowing about: a crowned tooth hurts, the dentist does a root canal, it still hurts, the root canal is redone, it still hurts, the crown is replaced, and the pain continues. Each round of treatment feels logical in the moment, but if the underlying cause is nerve-related phantom pain rather than a structural problem, additional procedures will not help and may make the situation worse. Atypical odontalgia after dental treatment is well-documented, and the persistent pain can continue even after extraction of the tooth.7Journal of Nepalese Prosthodontic Society. Atypical Odontalgia or Phantom Tooth Pain: Current Evidences for Better Understanding, Diagnosis and Management This is why diagnosis before treatment is so important: if the standard workup keeps coming back clean, stepping back and considering a neuropathic explanation is more productive than escalating to the next procedure. An orofacial pain specialist can assess whether the pain is being generated by the nerve pathway itself rather than by the tooth, and management strategies such as low-dose tricyclic antidepressants or topical agents have shown benefit in these cases.