Molars are the large back teeth designed for grinding food, and they are subjected to immense biting forces that frequently cause them to crack. Molar cracks are common in dentistry, ranging from microscopic surface flaws to fractures that split the entire tooth. Understanding the signs of a cracked molar is important because early detection can mean the difference between a simple fix and losing the tooth entirely. Identifying a crack often relies on physical sensations, as the most problematic fractures are frequently hidden from plain view.
The Challenge of Visual Detection
To the untrained eye, a cracked molar often looks like nothing at all. Many significant cracks are microscopic at the surface and travel deep into the tooth structure where they are not visible. Cracks may also be hidden beneath the gum line or originate under an existing filling or crown, making them impossible to see without removing the restoration.
Even when a crack is present on the chewing surface, it can be extremely fine and blend seamlessly with the molar’s natural grooves. This makes patient self-diagnosis highly unreliable. Dentists utilize specialized tools to overcome these visual obstacles, such as transillumination. Transillumination involves shining a fiber-optic light through the tooth, which highlights a fracture line because the crack reflects the light beam, creating a distinct light and dark area.
Classifying Cracks by Appearance
While many cracks are visually elusive, others have distinct appearances that help classify their severity. The most benign cracks are craze lines, which are fine, vertical, hairline fractures contained only within the outer enamel layer. These lines are common in adult teeth and may stain over time, but they rarely cause symptoms or require treatment.
A fractured cusp occurs when a piece of the molar’s chewing surface breaks away, often presenting as a visible chip or gap. This break typically originates from the biting surface and extends downward, sometimes exposing the underlying yellowish dentin layer. Loss of a cusp often occurs in molars with large existing fillings, which weaken the remaining tooth structure.
The most severe visual presentation is the split tooth or a vertical root fracture. A split tooth has a clear fracture line traveling from the crown down toward the root, resulting in two distinct, movable segments that may separate slightly under biting pressure. A vertical root fracture begins in the root and moves upward, often leading to localized gum inflammation or a deep, isolated pocket around the tooth.
Accompanying Symptoms and Sensations
Since visual confirmation is challenging for the average person, the physical sensations accompanying a cracked molar often become the primary indication of a problem. The classic signs, known as cracked tooth syndrome, involve pain that is difficult to pinpoint to a specific tooth. This pain is often intermittent and erratic, occurring only when the crack is stimulated.
A common symptom is a sharp, brief pain that occurs when biting or chewing, particularly when releasing the bite pressure. When pressure is applied, the crack segments are forced apart, stimulating the dentin and pulp. The sudden release of pressure allows the segments to snap back together, causing a fleeting, intense sensation.
Another sign is a sudden, sharp sensitivity to extreme temperatures, especially cold, or to sweet foods. This happens because the crack compromises the protective enamel layer, allowing stimuli to rapidly reach the sensitive pulp tissue. If the crack extends deep enough to fully involve the pulp, the pain may become a continuous dull ache, sometimes exacerbated by heat.
Next Steps: Professional Confirmation and Action
If characteristic pain or sensitivity symptoms appear, seeking immediate professional dental evaluation is the necessary next step. Early detection significantly improves the prognosis for saving the tooth and preventing more extensive procedures. While waiting for the appointment, avoid chewing on the affected side and stick to softer foods to prevent the crack from deepening.
During the evaluation, a dentist employs specific diagnostic techniques to confirm the crack’s location and severity. These techniques include having the patient bite down on a specialized instrument, like a “Tooth Slooth,” which applies selective pressure to individual cusps to reproduce the pain. The dentist may also use a periodontal probe to check for an isolated deep pocket, which indicates the fracture has extended to the root.
X-rays may be taken to check for signs of infection or bone loss around the root, which are late indicators of a severe fracture. Once the crack is located and classified, the dentist determines the appropriate course of action, focusing on stabilizing the tooth and preventing the crack from progressing.