A sharp, sudden pain that occurs specifically when you bite down is a distinct dental symptom, often signaling a localized mechanical issue within the tooth structure. This discomfort differs from generalized sensitivity to hot or cold temperatures. Chewing places physical stress on the tooth, exposing an underlying problem that remains silent at other times. Because this pain is directly triggered by an external force, a professional evaluation is necessary to pinpoint the exact location and cause of the structural failure.
Physical Causes of Pain
The most frequent cause of sharp, intermittent pain when biting is a structural defect known as Cracked Tooth Syndrome (CTS). This occurs when a hairline fracture extends from the chewing surface down into the tooth’s underlying layers. When you bite down, pressure forces the segments of the cracked tooth to flex or separate slightly, irritating the sensitive tissue underneath. Pain is often felt both on biting and upon release of pressure, as the fragments snap back together.
This structural compromise is common in teeth with large, existing fillings, which may have weakened the overall structure. A failing or loose filling can also cause pressure pain if the bond breaks down, transferring movement to the sensitive dentin beneath. Significant dental decay that has progressed deep into the dentin layer can also cause acute pain when pressure is applied. The biting force compresses the dentinal tubules, which are microscopic channels leading directly to the tooth’s nerve.
Internal Structures and Nerve Pain
Beyond external structural issues, pain can originate from inflammation deep within the tooth’s internal nerve tissue, known as the dental pulp. When decay or a crack reaches the pulp, the tissue swells inside the rigid walls of the tooth, a condition called pulpitis. Chewing pressure increases the fluid dynamics and pressure within the inflamed pulp chamber, which the nerve registers as sharp pain.
The severity of the inflammation determines if the pulpitis is reversible or irreversible, but both can cause pain when biting. Pressure sensitivity can also indicate inflammation of the periodontal ligament (PDL), the fibers that anchor the tooth root to the jawbone. Biting strains the inflamed PDL fibers, signaling pain. This PDL inflammation often occurs when infection spreads from the tooth’s dying nerve out to the root tip.
How a Dentist Diagnoses the Problem
The diagnostic process begins with a comprehensive clinical examination, where the dentist visually inspects the tooth for discoloration, wear, or visible cracks. They use percussion—gently tapping the tooth—to test for inflammation in the surrounding periodontal ligament. Radiographic imaging, typically a periapical X-ray, checks the bone surrounding the root tip for signs of infection or abscess formation.
To pinpoint a subtle crack, the dentist performs a bite test using a device like a “Tooth Slooth” or a cotton roll. The patient bites down on the tool, isolating pressure to individual cusps or sections of the tooth. Pain experienced during the bite, or upon release of pressure, helps confirm the presence of a crack. Thermal testing, using a cold spray, assesses the vitality of the nerve tissue to differentiate between a simple crack and pulpitis.
Necessary Treatments and Next Steps
Treatment is directly determined by the underlying diagnosis and the depth of the issue. For minor cracks limited to the outer dentin, or for simple decay, a new dental filling or bonding procedure may be sufficient to seal the tooth and eliminate the biting pain. When a crack is deeper or involves a large portion of the tooth, a dental crown is often the necessary solution. The crown encircles and holds the tooth together, stabilizing the weakened structure and preventing the crack from flexing under pressure.
If the internal pulp tissue is irreversibly damaged or infected, the solution involves root canal therapy. This procedure removes the inflamed nerve and pulp tissue from the root canal system, eliminating the source of pain and infection. Following a root canal, a crown is almost always placed to protect the tooth structure from fracturing under chewing forces. Extraction remains the last resort when a crack extends too far below the gum line or if the tooth structure cannot be saved. Seeking prompt professional care is the most effective way to save the tooth and prevent the infection from spreading.