When a tooth hurts only when pressure is applied, such as when biting down or chewing, it signals a distinct problem different from simple sensitivity to hot or cold. This sharp or aching discomfort indicates a mechanical failure or an underlying structural issue within the tooth or its surrounding apparatus. The pain is caused by the physical force transmitted through the tooth, suggesting an investigation into the integrity of the tooth’s surface and internal structures is necessary. Understanding the source of this pressure-induced pain is the first step toward preserving the tooth and finding relief.
Pain from Cracks and Broken Surfaces
One of the most common causes of pressure-related pain is Cracked Tooth Syndrome (CTS), which involves a fracture often too small to be seen on a standard X-ray. When biting down on a tooth affected by CTS, pressure forces the two segments of the tooth to move apart slightly. This movement causes fluid within the tiny tubes, called dentinal tubules, to shift rapidly, stimulating the nerve in the pulp chamber and resulting in a short, sharp pain. The pain is frequently felt most intensely not when biting down, but when the biting pressure is suddenly released, as the crack segments snap back together.
This structural failure can also occur when a large piece of the tooth, called a cusp, fractures away, which often happens in molars that bear the brunt of chewing forces. A fractured cusp exposes the underlying, sensitive layer of dentin, leading to pain when pressure is applied directly to the now-moving fragment. Existing dental restorations, such as old fillings or crowns, can also be the source of pain if they begin to fail or loosen, creating a gap where the restoration meets the tooth surface. Under the force of biting, these loose restorations can shift, irritating the underlying tooth structure or allowing bacteria to penetrate.
Pain from Internal Nerve Inflammation
Pain on biting can also originate from inflammation or infection of the dental pulp deep within the tooth. If tooth decay progresses deep enough, it can reach the pulp chamber, which contains the nerve and blood vessels. When pressure is placed on a tooth with deep decay, the force is transmitted through the thin remaining layer of dentin, causing the inflamed nerve tissue to react sharply. This condition, known as pulpitis, means the nerve is already stressed, making it hypersensitive to mechanical stress.
A more severe cause is a periapical abscess, a collection of pus caused by a bacterial infection at the very tip of the tooth root. The body’s immune response to this infection creates swelling and a buildup of pressure within the confined space of the jawbone surrounding the root. When the tooth is bitten down upon, the root is pushed further into the inflamed, pus-filled socket, causing intense, throbbing pain because the pressure has nowhere to dissipate. In these cases, the pain is often more constant and severe than the fleeting pain caused by a crack.
Pain Originating in Supporting Structures
Sometimes, the tooth itself is structurally sound, but the pain comes from the tissues that hold it in place within the jawbone. Each tooth is suspended in its socket by the periodontal ligament (PDL), a network of fibers that acts as a shock absorber. If you unexpectedly bite down hard on a piece of ice or a popcorn kernel, the PDL can become traumatized or “sprained,” similar to any other ligament in the body. The resulting inflammation makes the tooth tender to the touch, causing a dull, bruised feeling whenever chewing pressure is applied.
Uneven pressure distribution across the teeth can also inflame the PDL, particularly after receiving a new filling or crown that is slightly too high. This “high spot” causes that single tooth to take a disproportionate amount of the biting force, leading to localized trauma and pain. Chronic habits like clenching or grinding the teeth, known as bruxism, can continually stress the PDL fibers, leading to chronic soreness and pressure sensitivity. On occasion, referred pain from a severe sinus infection can mimic tooth pain upon biting, as the pressure from the inflamed sinus cavity presses down onto the roots of the upper back teeth.
Immediate Steps and Professional Diagnosis
If you experience pain when biting, the most immediate and practical step is to protect the affected tooth from further mechanical stress. This involves avoiding chewing on the painful side and switching to a soft diet to minimize the force applied. Over-the-counter pain relievers, specifically non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, can help manage the pain by reducing the underlying inflammation in the pulp or the supporting ligament.
A dental professional will employ several specific techniques to accurately diagnose the source of the pressure pain. Dentists often use a specialized plastic instrument, sometimes called a “tooth sleuth” or “Bite Dx,” which allows the patient to bite down on individual cusps of the tooth to pinpoint the exact location of a crack. They also use percussion testing, gently tapping the tooth to check for PDL inflammation, and X-rays to look for signs of decay or infection at the root tip. Since pressure-induced pain rarely resolves on its own and often indicates a progressive structural or infectious problem, professional intervention is necessary to prevent the issue from escalating to nerve death or complete tooth fracture.