A cracked tooth, often called cracked tooth syndrome, is a common dental concern that presents a diagnostic challenge because the fracture may be nearly impossible to see. This incomplete fracture runs through the tooth structure, sometimes extending from the chewing surface deep into the root. The crack can be nearly invisible, even on standard X-rays, making the specific type of pain experienced by the patient the primary indicator. Symptoms are highly variable but share a distinct pattern of discomfort.
The Signature Pain of a Cracked Tooth
The most defining characteristic is the sharp, sudden jolt of pain that occurs when chewing, especially on hard or sticky foods. This discomfort happens because the crack allows the two segments of the tooth to flex or move independently under biting pressure. This movement irritates the sensitive inner layer of the tooth, the dentin, which contains microscopic fluid-filled tubules connected to the nerve.
The sensation often intensifies not when the full bite force is applied, but rather at the moment the pressure is released, known as “pain on release” or “rebound pain.” This phenomenon occurs when the fractured pieces snap back into their original position, causing sudden, intense nerve stimulation. Unlike the constant, dull ache of a cavity, the pain from a crack is typically intermittent and erratic, making the affected tooth difficult to pinpoint.
Another common symptom is heightened sensitivity to temperature changes, particularly cold stimuli. When cold air or liquid touches the tooth, it moves fluid within the exposed dentinal tubules, leading to sudden, intense pain. This sensitivity signals that the crack has compromised the protective layers, allowing external stimuli to reach the nerve. If the crack extends further into the dental pulp, the pain can evolve into a constant, throbbing ache similar to an infection.
Factors That Increase the Risk of Tooth Cracking
Several factors contribute to the risk of a tooth developing a crack, often related to cumulative stress over time. Teeth with large, older dental fillings are vulnerable because the restorative material weakens the surrounding structure. This loss of natural material compromises the integrity of the cusp, the pointed chewing surface.
Habitual teeth grinding or clenching, a condition known as bruxism, places excessive stress on the teeth, increasing the likelihood of microfractures. Aging also causes teeth to become more brittle and less resilient over time, making adults over 40 more prone to cracked tooth syndrome. Chewing on hard objects, such as ice or unpopped popcorn kernels, can deliver a sudden, intense force that initiates a crack.
How Crack Location Affects the Sensation
The exact experience of a cracked tooth is heavily influenced by the depth and location of the fracture. The mildest form, known as craze lines, involves only the outer enamel layer and appears as tiny, superficial vertical lines. These lines are common in adult teeth and typically cause no pain or only mild, fleeting sensitivity, requiring no treatment beyond monitoring.
A fractured cusp occurs when a piece of the tooth’s chewing surface breaks off, usually around an existing filling. The pain is sharp and occurs when pressure is applied directly to that specific cusp. The crack often does not extend deep enough to involve the tooth’s nerve, meaning temperature sensitivity is usually minimal or absent.
In contrast, a vertical root fracture begins in the tooth’s root, often below the gum line, and moves upward toward the chewing surface. Because the crack starts deep, symptoms may be subtle initially but can progress to a persistent, deep ache. This type of fracture often causes gum swelling and localized bone loss, and can be mistaken for advanced periodontal disease.
Immediate Steps and Professional Confirmation
If a person suspects they have a cracked tooth, they should immediately avoid chewing on the affected side to prevent the crack from spreading. Over-the-counter pain relievers can help manage discomfort while waiting for an appointment. Contacting a dentist promptly is important, as early diagnosis significantly improves the chances of saving the tooth.
Professional diagnosis is challenging because the crack is often difficult to see. Dentists use specialized tools to confirm the problem and pinpoint the fracture location. These tools include high-magnification visual inspection and a diagnostic procedure called a bite test.
During a bite test, the patient bites down on a specific plastic tool, such as a Tooth Slooth or FracFinder, on each cusp individually. If the tooth is cracked, this replicates the characteristic “pain on release,” isolating the affected area. Other techniques involve transillumination, which uses a fiber-optic light to make the crack line visible, and the application of a dental dye to reveal the fracture’s full extent.