Most teeth have craze lines present in their enamel. Craze lines are infractions or very subtle cracks that are visible in the enamel shell of the teeth. Most are not concerning but some may present concern depending on their appearance and location.
When a craze extends deeper through the enamel into the underlying dentin it is considered a crack. Cracks are most frequently seen around large or aged silver fillings, but can be present in teeth with no dental work at all. Lower second molars are notorious for developing cracks. Cracks are problematic because they do not heal and typically propagate and progress into a worse condition. Symptoms may occur and will vary depending on the depth and position of the crack. Sometimes when chewing certain types of food, the tooth flexes / the crack opens microscopically, and patients experience a quick discomfort known "cracked-tooth-syndrome". Your dentist will typically recommend crowning a tooth that has cracked-tooth-syndrome as an attempt to splint the crack and resolve the symptoms. Endodontic treatment may be necessary if symptoms persist or worsen. Your dentist may even recommend crowning a tooth that has no symptoms if it has a significant crack present. This preventative measure protects the tooth and minimize the chances for further crack propagation and a worsening condition.
A cuspal fracture occurs when a cracked tooth propagates obliquely under a cusp resulting in the loss of a corner of a molar or a side of a bicuspid. This most often occurs in a tooth that has a large filling present, but it can happen in a tooth with no dental work.
A split tooth occurs when a crack extends vertically into the root and beyond the level that the gums or bone attach to the tooth. This can be a problem because over time it can result in destruction of the adjacent surrounding bone as the crack becomes contaminated. There is no way to clean out the contamination in the crack. This results in deep pocketing in the gums, pain to biting, swelling, or mobility of the tooth. Because the type of crack will also extend into the pulp, it often also simultaneously causes endodontic signs and symptoms. Determining the extent of this type of fracture can be very difficult, especially if it is just recently cracked. This can be a particularly frustrating situation because patient may have significant symptoms requiring endodontic treatment, but the prognosis for saving the tooth may be unpredictable. If it can be determined that the split is extensive, your dentist may recommend extraction of the tooth.
Vertical Root Fracture
Vertical root fracture occurs when the root is fractured and has resulted in destruction of the surrounding bone. This most often occurs on teeth that are heavily restored and have previously root canal treatment, though it can happen in teeth with no prior history of dental work. In rare cases the fracture is confined to the very tip of the root, in which case surgery may be an option. Most often however, vertical root fractures are catastrophic for the tooth and it must be extracted.