Sharp, sudden pain when biting down suggests a structural or internal problem within the tooth or its supporting tissues. Unlike sensitivity to temperature, pain upon occlusion—the moment teeth touch or pressure is applied—indicates a direct mechanical or inflammatory response to biting force. This symptom signals that the integrity of the tooth is compromised, requiring professional assessment to prevent progression to more serious damage. The source of pain can range from a minute crack in the enamel to a deep infection affecting the entire tooth structure.
Structural Issues Causing Immediate Pain
The most common cause of sharp pain when biting is Cracked Tooth Syndrome (CTS). This occurs when a hairline fracture, often too small for X-rays, extends into the dentin layer. When biting down, the force causes the tooth segments to flex or move apart, which the pulp tissue immediately registers as pain. A distinct feature of CTS is “rebound pain,” felt most intensely upon the release of biting pressure. As pressure is released, the cracked pieces snap back, causing sharp, fleeting discomfort. This mechanical flexing can also be triggered by chewing on hard or fibrous foods.
Restorations that are failing or improperly positioned can also cause biting pain. A dental filling or crown that is slightly too high, known as hyperocclusion, creates premature contact with the opposing tooth. This concentrates excessive force onto a small area, straining the periodontal ligament (PDL)—the tissue that anchors the tooth to the jawbone. This constant, uneven pressure leads to pain that feels like biting on a rock. Similarly, a loose filling or crown that shifts under chewing force can expose the sensitive underlying tooth structure, causing immediate discomfort.
Inflammatory and Infectious Root Causes
Biting pain can signal inflammation or infection exacerbated by chewing pressure. Inflammation of the dental pulp (nerve and blood vessel tissue) is known as pulpitis. If the inflammation is mild, perhaps caused by a small cavity or recent dental work, it may be reversible, causing brief pain that quickly subsides. If decay or trauma has advanced, the pulpitis becomes irreversible, leading to severe, spontaneous pain that lingers. At this stage, biting down forces fluids against the damaged nerve tissue within the tooth, causing intense discomfort. Untreated pulpitis can eventually lead to a periapical abscess, a pocket of pus that forms at the root tip.
A periapical abscess causes significant pain when biting because chewing pressure pushes the tooth down, compressing the inflamed sac of infection against the jawbone. This pressure leads to a severe, throbbing ache that worsens when the tooth is used. The pain from an abscess signifies a severe infection requiring immediate attention to prevent spreading into the jaw or facial spaces.
Non-Dental and Supporting Structure Pain
Sometimes, biting pain originates not from the tooth structure, but from the surrounding support system or referred pain. The periodontal ligament (PDL) acts as a shock absorber; if it becomes inflamed (a “bruised tooth” or PDL sprain), it causes pain when chewing. PDL inflammation often results from excessive forces like aggressive tooth grinding (bruxism), a recent deep filling, or biting down unexpectedly on a hard object.
Advanced periodontal disease can also cause biting pain because the infection damages the bone and ligament, causing the tooth to become mobile. When pressure is applied, the tooth’s movement within its socket irritates the remaining supporting tissues, resulting in discomfort. Pain in the upper back teeth can also be a symptom of a sinus infection (sinusitis), as these roots are located close to the maxillary sinuses. Swelling and pressure within the sinus cavity can press on the nerves of the upper tooth roots, mimicking a toothache, especially when the head is moved. Similarly, issues with the temporomandibular joint (TMJ) can be perceived as pain in the teeth. This referred pain occurs when muscle tension or joint dysfunction radiates into the nearby jaw and teeth.
Diagnostic Steps and Professional Treatment
If biting pain occurs, immediate self-care involves avoiding chewing on the affected side and taking over-the-counter anti-inflammatory pain relievers. Switch to a soft diet and avoid hot or cold extremes until consulting a dental professional. If the pain is accompanied by swelling, fever, or difficulty swallowing, this indicates a spreading infection and requires immediate emergency attention.
A dentist uses specific tools to pinpoint the source of the pain, which is often challenging to locate. One specialized instrument is the Tooth Slooth, a small plastic device used to apply pressure to one cusp at a time. Pain upon biting or releasing pressure with this tool helps confirm Cracked Tooth Syndrome and identifies the fracture location. Diagnosis also includes X-rays, which may not show a crack but can reveal bone loss from periodontal disease or an abscess at the root tip. Thermal testing assesses the vitality of the pulp tissue, differentiating between reversible and irreversible pulpitis. Treatment is determined by the cause: a high filling is corrected with a quick adjustment, while a minor crack may be stabilized with a crown. More serious issues, such as irreversible pulpitis or an abscess, require endodontic therapy, commonly known as a root canal, to remove the damaged pulp and save the tooth.