Pain when chewing or biting down signals a mechanical issue within the tooth or its supporting structures. This sensation differs from generalized sensitivity to cold or heat, as it is directly triggered by the physical force of the bite. The presence of pain upon biting indicates that mechanical pressure is irritating internal tissues, requiring immediate professional attention.
When a Tooth Cracks or Breaks
One frequent cause of sharp, isolated pain when biting is a structural failure known as Cracked Tooth Syndrome (CTS). This condition involves a small, often invisible crack extending from the chewing surface downward, typically affecting the back molars. When biting, the force causes the segments of the cracked tooth to flex or shift slightly. This movement momentarily exposes the sensitive inner dentin and the nerve-rich pulp to mechanical irritation.
The flexing irritates the nerve fibers, resulting in a sudden, intense, and often fleeting burst of pain. Discomfort is sometimes most noticeable when the biting force is released, known as “rebound pain,” as the segments snap back together. Fractured cusps, common breaks around large fillings, operate similarly when stressed under the load of chewing. A faulty or leaking dental restoration can also allow pressure to reach the underlying tooth tissue, mimicking the symptoms of a crack.
Deep Decay and Root Issues
Pain on biting can originate from internal inflammation or infection within the tooth’s pulp chamber. When decay progresses deep enough to approach the pulp, it causes inflammation known as pulpitis. If the pulpitis is irreversible, the inflamed tissue is already under pressure inside the rigid tooth walls. The force of biting transmits through the tooth structure, severely exacerbating this pre-existing irritation.
A more advanced issue is a periapical abscess, a collection of pus and infected tissue at the root tip. Bacteria from deep decay or trauma can kill the nerve, allowing the infection to spread into the jawbone. When biting down, pressure transfers through the tooth to the inflamed tissue surrounding the root, which is confined within the bony socket. This compression of the abscessed area causes intense, localized pain that worsens significantly upon chewing.
Issues with the Ligament and Supporting Bone
The tooth is suspended within its socket by the Periodontal Ligament (PDL), a thin band of connective tissue that acts as a shock absorber. When the PDL becomes inflamed, the tooth becomes highly sensitive to vertical pressure. This inflammation, often called a “bruised tooth,” can result from periodontal trauma, such as biting down on an unexpected object or severe teeth grinding (bruxism).
The PDL may also become inflamed if a new filling or crown is placed slightly high, causing it to contact the opposing tooth too soon. This subjects the tooth to excessive force with every bite. Periodontal disease can lead to bone loss around the root, compromising the tooth’s stability. This reduced support forces the remaining PDL and surrounding tissue to bear an abnormal load, making the tooth tender and painful when pressure is applied.
Seeking Professional Evaluation
Any isolated pain when biting requires professional evaluation to pinpoint the exact cause, as the treatment varies significantly depending on the source. The diagnostic process begins with a detailed history and a clinical examination to visually inspect the tooth and surrounding gums.
Diagnostic Tools
Dentists use several methods to locate the source of the pain:
- Targeted pressure application using a Tooth Slooth or cotton swab to reproduce the pain and locate a crack.
- Radiographic imaging (X-rays) to check for deep decay, bone loss, or infection at the root tip.
- Percussion tests, gently tapping the tooth to gauge inflammation in the surrounding ligament.
- Thermal sensitivity checks to determine the health and vitality of the internal nerve tissue.
These tests guide the decision toward treatments like a simple filling replacement, a crown for a cracked tooth, or root canal therapy for an infected pulp.