A cracked tooth, or fracture, is a break in the hard structure of the tooth, affecting the outer enamel and sometimes the underlying layers. This damage compromises the tooth’s structural integrity and can result from trauma, teeth grinding, or the daily stresses of chewing. The experience of pain is highly variable, which often confuses people. A significant fracture may cause only minor discomfort, while a seemingly small crack can lead to intense, persistent pain.
The Different Types of Tooth Fractures
Dentists classify tooth fractures into five distinct types based on their location and depth. Craze lines are the most superficial, appearing as hairline cracks that affect only the outermost enamel layer. These lines do not extend into the dentin, are common in adult teeth, and typically pose no threat to the tooth’s health.
A fractured cusp involves a break in the chewing surface, often occurring around a large existing filling. This fracture may cause a piece of the cusp to separate, but it usually does not extend into the pulp chamber, limiting the severity of symptoms. A true cracked tooth is a vertical fracture that starts on the chewing surface and extends downward toward the root, potentially reaching the pulp and the root canal system.
When a crack progresses to split the tooth into two separate segments, it is classified as a split tooth. This condition is a severe progression of a cracked tooth, and the prognosis for saving the entire tooth is often poor. A vertical root fracture begins below the gum line in the root and travels upward toward the chewing surface. This type of fracture is difficult to detect early because symptoms may not appear until the surrounding bone or gum tissue becomes infected.
Understanding Why a Cracked Tooth May or May Not Hurt
The presence or absence of pain links directly to the depth of the fracture and whether it exposes the sensitive inner tissues. When a crack is limited to the outer enamel, such as with craze lines, there is generally no pain because the enamel contains no nerves. Pain begins when the fracture extends into the dentin (the layer beneath the enamel) or reaches the pulp tissue, which contains the tooth’s nerves and blood vessels.
One common pain symptom is a sharp, intermittent discomfort when biting or releasing pressure, known as the “wedge effect.” As pressure is applied, the fractured segments move slightly, causing the crack to open and close. This movement irritates the pulp tissue inside, stimulating the nerves and resulting in a sudden, brief jolt of pain that quickly disappears once the biting pressure is removed.
Temperature sensitivity, particularly to cold, results from the crack exposing the microscopic dentinal tubules that run from the dentin surface to the pulp. The accepted explanation is the hydrodynamic theory. This theory posits that rapid fluid movement within these exposed tubules, triggered by thermal or osmotic changes, stimulates the nerve endings in the pulp, causing sharp, transient pain associated with dentin exposure.
Conversely, a deep crack reaching the pulp may cause constant, severe pain if it leads to inflammation or infection. If the pulp tissue dies due to persistent irritation and bacterial invasion, the pain may temporarily subside, leading to a false sense of relief. However, the necrotic tissue will eventually cause infection and inflammation in the bone surrounding the root tip, resulting in a constant, throbbing ache and swelling.
Immediate Action and Professional Diagnosis
If you suspect a cracked tooth, taking immediate action can help prevent the crack from worsening before you see a dentist. Gently rinsing your mouth with warm water helps clean the area and remove debris that might irritate the crack. Applying a cold compress to the outside of the cheek near the affected area can reduce swelling and provide temporary pain relief.
It is necessary to avoid chewing on the affected side of the mouth to prevent putting further stress on the fracture. Contacting your dentist immediately to schedule an examination is the most important step, even if the pain is mild or intermittent. Over-the-counter pain relievers can manage discomfort, but they are not a substitute for professional treatment.
A professional diagnosis requires specific tests, as minor cracks are often invisible on standard dental X-rays. A dentist begins with a thorough visual inspection, sometimes using magnification or specialized dental dyes to make the crack more visible. Transillumination, where a bright fiber optic light is shone through the tooth, helps locate the fracture line because the light will not travel past the crack.
The most definitive diagnostic tool involves asking the patient to bite down on a specialized instrument, such as a plastic biting stick, on different cusps. This test recreates the specific sharp pain experienced when the crack is stressed. While X-rays check for signs of infection in the bone or pulp involvement, they are more useful for confirming the extent of damage in the root rather than identifying the initial crack on the chewing surface.
Repair Options Based on Fracture Severity
The treatment pathway depends entirely on the type and severity of the fracture. For minor cracks like craze lines, no intervention is typically needed beyond routine monitoring. A dentist may polish the tooth surface or apply a thin layer of protective dental bonding for cosmetic reasons. A fractured cusp can often be restored with a new filling or an onlay, which covers the chewing surface to prevent further damage.
When the crack extends deeper but has not yet reached the pulp, the most effective treatment is the placement of a full-coverage crown. The crown acts like a helmet, holding the fractured segments together and preventing the crack from propagating further down the root. This intervention stabilizes the tooth structure and reduces the movement that causes pain upon biting.
If the crack has extended into the pulp chamber, causing irreversible damage or infection, root canal therapy is required to save the tooth. This procedure involves removing the damaged pulp tissue and sealing the inner part of the tooth, which is then typically protected with a crown. If a split tooth or a vertical root fracture extends too far below the gum line, the tooth is often unsalvageable, and extraction is the only viable option to prevent infection spread.