Why does my tooth hurt? Tooth pain can strike suddenly or build gradually, but it always signals that something isn’t right. Whether it’s a sharp jolt while biting down or a dull, throbbing ache that won’t go away, understanding the cause is the first step toward relief. From cavities and gum infections to cracked teeth, sensitivity, and even sinus problems, there are many possible reasons for dental discomfort. In this guide, we’ll break down the most common causes of tooth pain, how to tell them apart, and what to do next.

• Tooth Decay (Cavities): Bacteria in dental plaque produce acids that eat away tooth enamel, forming cavities. As decay penetrates inward toward the dentin (beneath the enamel), it exposes nerve endings and causes sharp pain, especially with sweet, hot or cold foods . The Mayo Clinic notes that tooth decay is the most common cause of toothaches – you might feel pain when consuming sweets or very cold/hot drinks as the first warning sign of a cavity.
• Gum Disease & Infection: Advanced gum disease (periodontitis) and gum infections can trigger tooth pain. As gums become inflamed and begin to recede, tooth roots and nerves can be exposed, leading to aching or sharp pain . In severe cases, the infection may spread to supporting bone and tissues, making teeth feel loose or very tender .
• Tooth Damage (Cracks, Chips or Trauma): A cracked tooth lets irritants reach the inner pulp (nerve) of the tooth. Biting down moves the cracked pieces and aggravates the pulp, resulting in erratic or sharp pain when chewing or with temperature changes . Even a hairline crack may hurt intermittently, and untreated cracks can lead to nerve inflammation or infection.
• Tooth Sensitivity (Enamel Erosion/Exposed Dentin): Worn enamel or receding gums can expose the dentin layer (containing microscopic tubules to the nerve). This causes quick, stabbing pain when teeth contact cold, hot, sweet or acidic substances . Common causes of tooth sensitivity include over-brushing, acid erosion, gum recession and old worn fillings .
• Impacted or Erupting Teeth: Teeth that haven’t properly erupted (often wisdom teeth) can press against adjacent teeth or tissues. This pressure and the surrounding inflammation cause dull or throbbing pain, jaw stiffness, or gum swelling near the back of the mouth . Horizontally impacted wisdom teeth are especially likely to hurt because they push on neighboring molars .
• Grinding (Bruxism) and Jaw Disorders: Chronic tooth grinding or clenching wears down enamel and strains the teeth and jaw muscles. Over time this leads to generalized tooth pain or tenderness, cracked teeth, and jaw discomfort . In addition, temporomandibular joint (TMJ) disorders can mimic a toothache. Because the TMJs are near many facial nerves, TMJ pain often radiates into the jaw and teeth , and jaw misalignment can place extra pressure on certain teeth .
• Sinus or Other Medical Causes: Sinus infections (sinusitis) frequently cause referred pain in the upper back teeth. Inflammation of the sinuses (especially the maxillary sinuses above the upper molars) can press on tooth roots, making those teeth ache even without a dental problem .  Less commonly, other conditions (like growing wisdom teeth or rare infections such as Ludwig’s angina) can produce a toothache. For example, Mayo Clinic notes that a sinus infection can definitely feel like a toothache in the upper back teeth .

Each of these factors can produce the sensation that “something is wrong” with a tooth. In many cases, the pain is a warning sign: for instance, a new sharp pain while biting could indicate a hidden crack, while persistent throbbing might point to an abscess.

Tooth Decay (Cavities) and Pulpitis

Tooth decay occurs when acids from plaque-bacteria erode enamel. Over time this creates a cavity (hole) in the tooth . Early on, decay may only cause mild sensitivity – you might notice a quick shock of pain when eating sweets or drinking something very hot or cold . As the cavity grows and reaches the softer dentin layer beneath the enamel, the nerve-rich center (pulp) becomes irritated. This often produces throbbing or persistent toothaches.

If decay is not treated, it can lead to pulpitis (inflammation of the pulp). Pulpitis causes intense, lingering pain even after the stimulus is removed . For example, you may have a sharp pain that continues minutes after drinking a cold drink, or spontaneous aches at night. Left unchecked, the inflamed pulp can die and form an abscess at the root, which we cover next.

Gum Disease and Dental Infections

Gum disease is a chronic bacterial infection of the gums (gingivitis or periodontitis). In early gingivitis, gums are red, swollen and may bleed, usually without severe pain . However, if it progresses, the gums begin to pull away from the teeth and form pockets of infection. Advanced periodontitis can erode the bone that supports teeth, causing teeth to loosen. As gums recede, tooth roots become exposed, often causing sensitivity or pain .

Infections at the root of a tooth (often from deep decay) cause a dental abscess. An abscess is a pocket of pus that forms when bacteria invade the pulp chamber. It typically causes severe, throbbing pain and swelling around the affected tooth . You might notice the pain worsen when lying down, or see redness and a bump on the gum. Dentists can often identify an abscess by tapping on the tooth – an abscessed tooth will be extremely tender to pressure . Immediate dental treatment (draining the abscess or performing a root canal) is needed to relieve abscess pain and prevent spread of infection.

Cracked, Chipped or Traumatized Teeth

Teeth cracked or chipped by injury or grinding can hurt in specific ways. A crack might be visible or microscopic, but either way it allows external stimuli to reach inner layers of the tooth. When you bite down, the cracked segments can move minutely, irritating the pulp. This causes shooting or “electric shock” pain on pressure. An experienced endodontist explains that biting on a cracked tooth often produces erratic pain, and the tooth may also become sensitive to temperature changes .

Symptoms of a cracked tooth include sharp pain when chewing (especially on one side), pain from hot or cold, and relief when pressure is released. In some cases, the tooth may hurt sporadically and then suddenly become painful “all by itself” as the crack worsens . Large fractures often require prompt treatment (filling, root canal or crown). Even a small chip near a nerve can be quite painful if not sealed quickly.

Tooth Sensitivity from Enamel Erosion

Even without obvious decay or damage, teeth can hurt due to sensitivity. This occurs when the protective enamel wears away and exposes the underlying dentin layer. Dentin has microscopic tubules that lead directly to the tooth’s nerve. When these tubules are exposed, common triggers (cold air, cold drinks, hot foods, or acidic foods) cause sharp, momentary pain .

Enamel erosion can happen from acidic diets, aggressive brushing, or simply age and wear. Gum recession (from gum disease or brushing too hard) similarly exposes root surfaces. A dental school explains that once dentin is exposed, stimuli easily reach the pulp nerves and trigger sensitivity . Typically, this sensitivity is brief and occurs only when triggered, unlike the deeper ache of decay. Using desensitizing toothpaste, fluoride treatments, and careful brushing can alleviate this type of pain.

Impacted and Wisdom Teeth

Wisdom teeth (third molars) are common culprits of late-onset tooth pain. Because they erupt last, the jaw may not have room, causing them to grow at an angle or become “impacted” under the gum. An impacted wisdom tooth can press on adjacent teeth or bone, causing dull, throbbing pain and jaw discomfort . The Cleveland Clinic notes that horizontally impacted wisdom teeth often hurt especially badly because of the pressure they exert on the neighboring teeth .

Impacted teeth also create pockets that collect debris and bacteria, leading to infections or cavities in the wisdom tooth or nearby molar. If an impacted tooth becomes infected, symptoms include sharp localized pain, swollen or bleeding gums around that area, and possibly fever . Often the only remedy for an impacted, painful wisdom tooth is surgical removal.

Grinding (Bruxism) and TMJ Disorders

Many people grind or clench their teeth without realizing it, especially during sleep. This bruxism wears down enamel and puts excessive force on the teeth and jaw muscles. Over time, you may wake up with sore, tender teeth or headaches. Mayo Clinic lists “teeth that are flattened, fractured or chipped” as a sign of grinding, along with jaw pain and tooth sensitivity . The constant pressure can make teeth sensitive and even crack (linking back to a cracked tooth cause).

Additionally, TMJ (temporomandibular joint) disorders can masquerade as a toothache. Since the TMJs (jaw joints) and associated muscles are located near many facial nerves, pain from TMJ dysfunction often radiates into the teeth or face . For example, a misaligned bite due to TMJ issues can put extra pressure on certain teeth and cause localized tooth pain . Often, treating the underlying bruxism or TMJ problem (with a night guard, stress management, or a referral to a specialist) is necessary to relieve the toothache-like symptoms.

Sinus and Other Medical Causes

Not all tooth pain originates in the teeth. A sinus infection or congestion can create the sensation of toothache, usually in the upper rear teeth. The roots of the upper molars lie very close to the maxillary sinus cavities. When those sinuses become inflamed, the pressure and swelling can push on the nearby tooth roots, mimicking a toothache . Mayo Clinic confirms that sinusitis often causes pain in the upper back teeth, even though the teeth themselves are healthy .

Other systemic issues can occasionally cause tooth discomfort. For example, large undiagnosed cavities or dental abscesses can lead to secondary sinus infections. Very rarely, life-threatening infections in the floor of the mouth (Ludwig’s angina) or viral illnesses may present with jaw/teeth pain .  However, in practice, if a dentist rules out dental causes, doctors will then consider sinusitis, TMJ or other medical conditions as the culprit .

Why Does My Tooth Hurt – What to do?

Because tooth pain has many possible causes, it’s important to address it promptly. Begin with basic self-care: rinse gently with warm salt water, carefully floss to remove any lodged food, and use over-the-counter pain relievers (acetaminophen or ibuprofen) as directed. Avoid chewing on the sore side or very hard foods. A cold compress outside the cheek can reduce swelling if a dental injury occurred.

At the same time, schedule a dental exam as soon as possible. Dentists can pinpoint the cause with an exam and X-rays (looking for cavities, abscesses, cracks, etc.) . Many issues (like cavities or gum disease) are much easier and less painful to treat when caught early. If an infection is present, your dentist may prescribe antibiotics or perform a root canal or drainage to remove the abscess . Mouthguards can be provided for bruxism, and impacted wisdom teeth can be evaluated for possible removal.

In summary, a toothache is usually a symptom of an underlying problem: it might be a cavity, gum infection, injury, or even something like sinusitis or TMJ. We’ve covered the most common causes above. In any case of intense, persistent or worsening tooth pain, or pain accompanied by fever or swelling, you should seek professional care immediately. The sooner the cause is found (and treated), the sooner you’ll find relief.

At Lemont Dental Clinic, our experienced team can evaluate the cause of your tooth pain and recommend the best treatment. Whether you need a filling for a cavity, root canal therapy for an abscess, a night guard for bruxism, or advice on treating sensitive teeth, we are here to help. Don’t ignore a nagging toothache — get in touch today!

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