Cracked Tooth Syndrome

One of the most difficult diagnoses in dentistry is Cracked Tooth Syndrome. The patient generally presents with sharp pain on chewing in a certain area of his mouth, but he or she frequently cannot tell which particular tooth hurts. The pain is generally associated with a posterior tooth which becomes evident when the patient is asked to bite on piece of wood or a special device like the Sleuth Tooth. As a rule, the dentist cannot see any problem with the tooth, either clinically or radiographicly. The tooth may have no fillings or decay, or it may have an intact filling with no visible associated problems. Nothing looks wrong, but the patient feels sharp pain upon biting pressure. Symptoms of sharp pain to pressure accompanied by no visible signs of a problem with the tooth are the hallmarks of cracked tooth syndrome.The diagnosis can be further confirmed when the dentist uses an instrument that rests on one part of the tooth at a time. There is frequently sharp pain when the pressure is applied to only one particular cusp, and not to others. If the tooth has a crack in it, the pain is caused by movement of the affected cusp. The other cusps generally prove to be non-painful when the same pressure is applied. The "movement" of the fragment is usually microscopic, and not visible to the naked eye. Q: When is a crack in a tooth not a crack? A: When it's a craze! Crazes are visible cracks in the enamel of the teeth.They are always painless and generally they are vertical (but not always). They are most noticeable in the front teeth, and frequently cause patients a lot of concern. They tend to form as we get older, and are considered to be a part of the normal anatomy of the teeth. Crazes develop because of the differences between the coefficients of thermal expansion of the enamel and the underlying dentin. When a person switches quickly between eating and drinking hot and cold foods, these two components expand and contract at slightly different rates causing cracks in the more brittle outer layer of enamel. The underlying dentin is less brittle and does not crack. Since the enamel and the dentin are bonded to each other molecule for molecule, there is no danger of the enamel or the tooth breaking. How can a tooth have a crack, but show no outward signs of a crack? When a real crack occurs in a vital tooth, the crack frequently does not propagate all the way through the tooth. This type of crack is called a greenstick fracture because, like a green branch from a tree, the fracture may be mechanically present, but the unbroken segments of the branch hold it together. The crack usually propagates through sensitive parts of the tooth (the dentin), many times involving the vital nerve. When pressure is applied to the cracked piece of the tooth, a small movement of tooth structure occurs which stimulates the nerve. Even though the movement is tiny, it hurts a lot! Since the tooth cannot heal itself, the pain is always present whenever pressure is applied to the biting surface of that tooth.The pain will not go away until one of two things happen. 1. The cracked piece of tooth may break off relieving the pain when pressure is applied to it. When this happens, the tooth can usually be repaired with a crown or a simple filling and the patient (and tooth) lives happily ever after. 2. The nerve may die as a result of the repeated assaults placed on it by the moving fragment of tooth. When this happens, the pain to pressure may stop, but the non-vital nerve leaves the patient vulnerable to a dental abscess unless a root canal, and subsequent crown are performed. Can cracked teeth be saved? Whenever we are dealing with a cracked tooth, the patient must understand that whatever treatment the dentist prescribes, and no matter how hard he or she tries, the tooth may still need to be extracted at some time in the future! Repair of any tooth thought to be cracked is always risky, and no guarantees can be made about the outcome. The safest way to repair a cracked tooth involves three steps: 1. Perform a root canal on the tooth. This procedure is absolutely necessary if the crack has propagated through the nerve space. While this procedure is not necessary if the crack does not involve the nerve, there is really no way for the dentist to determine if this is the case. 2. Once the root canal has begun, the dentist should look into the pulp chamber and try to see the crack. Unfortunately, the crack is not always visible to the dentist, even once the root canal procedure has been started and the chamber is empty. If a crack is seen in the floor of the chamber, it can be stabilized by bonding a passive post in each of the root canals on either side of the crack. Post placement in a root canal is NOT indicated if it can be determined that the crack runs through the orifice of that specific canal. The pulp chamber should be properly etched, bonded and filled with composite resin in order to help hold the tooth together internally. 3. Once the root canal is completed, a full coverage crown should be placed over the tooth.