Pain in a molar when biting down or releasing pressure indicates a mechanical or structural problem requiring professional assessment. This discomfort is distinct from generalized tooth sensitivity and suggests the physical action of chewing is stressing a damaged part of the tooth or its surrounding support structures. Because molars bear the brunt of chewing forces, they are highly susceptible to structural failures. The pain serves as a protective warning sign that a serious issue is developing.
Understanding Mechanical Stress and Pain
Two common causes of molar pain during biting involve internal tooth damage: Cracked Tooth Syndrome (CTS) and advanced inflammation of the inner nerve tissue. CTS involves a fracture line extending into the dentin, the layer beneath the outer enamel. When pressure is applied during a bite, the two segments of the tooth flex apart slightly, causing sharp, momentary pain.
The pain is often most intense when the bite is released, as the fractured segments snap back into position. This movement triggers mechanoreceptors within the dental pulp, resulting in a sudden, fleeting, shock-like sensation. Pain upon release is a key symptom distinguishing a cracked tooth from other dental issues.
Advanced dental decay can progress to cause inflammation of the pulp, known as pulpitis. When decay reaches the pulp, the nerve tissue swells within the rigid walls of the tooth, leading to increased internal pressure. Biting down transmits pressure through the tissue, pushing fluid onto the inflamed nerve and causing intense pain.
If inflammation progresses and the nerve tissue dies (pulp necrosis), an infection often develops at the root tip, forming an abscess. The pressure from this periapical abscess can slightly elevate the tooth in its socket. This elevation causes the tooth to contact the opposing molar first when biting, making it feel “high” and tender to pressure.
Other Causes Stemming from Existing Dental Work
Pain when biting can originate from issues external to the main tooth structure, often involving previous dental restorations or the supporting ligament. A common culprit is a filling or crown that is slightly too “high,” interfering with the normal alignment of the bite. Even a minuscule height difference causes the tooth to absorb excessive pressure, leading to inflammation of the periodontal ligament (PDL).
The PDL is a network of fibers that anchors the tooth within the jawbone socket and acts as a natural shock absorber. When a restoration is too high, the resulting uneven force overstresses this ligament. This inflammation, known as traumatic periodontitis, creates a sharp, localized pain when chewing that resolves once the restoration’s height is adjusted by a dentist.
PDL inflammation can also occur from non-restorative trauma, such as habitually clenching or grinding the teeth (bruxism). The constant, heavy force from bruxism strains the PDL, making the tooth tender when biting.
Defective or compromised restorations, such as a loose filling or a chipped crown, can allow movement under chewing force. This movement irritates the underlying tooth structure, causing pain and creating a pathway for bacteria to cause new decay beneath the existing dental work.
Immediate Steps and Triage
If you experience sudden, sharp molar pain when biting, immediately avoid chewing on the affected side of the mouth. Continuing to stress the tooth risks worsening the underlying damage, particularly if a crack is present. Switch to a soft-food diet until a dental appointment can be secured.
To manage discomfort temporarily, over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen can help reduce inflammation in the pulp or periodontal ligament. Follow dosing instructions carefully and do not exceed the recommended daily limit. These steps offer temporary relief.
Seek urgent dental care if the pain becomes severe, throbbing, or spontaneous, especially if it wakes you up at night. Red flags indicating an acute infection include swelling in the gums or face, a fever, or a pus-filled bump on the gums near the tooth. These symptoms suggest the problem requires immediate professional intervention to prevent the spread of infection.
Definitive Professional Treatment Options
The definitive treatment for molar pain when biting depends entirely on the professional diagnosis, which often involves dental X-rays and a specialized bite test.
For cases involving a high filling or crown, the solution is a simple occlusal adjustment. The dentist uses marking paper to identify and carefully grind down the high spot, which restores the proper bite alignment and allows the inflamed periodontal ligament to heal.
If the pain is caused by deep decay that has not yet destroyed the pulp, the dentist will remove the decay and place a new filling or a crown to protect the remaining tooth structure. If the pulp is irreversibly inflamed or infected, the standard treatment is root canal therapy. This involves removing the diseased pulp tissue from the interior of the tooth and sealing the root canals.
A crown is almost always placed afterward to protect the tooth from fracture. For Cracked Tooth Syndrome, treatment depends on the depth and direction of the fracture. A crown is frequently placed to stabilize the tooth by holding the fractured segments together, preventing further movement under chewing force. If the crack extends too far below the gum line or if the tooth is severely fractured or decayed beyond repair, extraction remains the final option.