Grinding and Clenching
Grinding and clenching are two of the most common causes of the wearing away of tooth enamel. However, they are also extremely preventable when detected early.
The trouble starts when we contact the opposing teeth, without any food in between them, for long periods of time, and higher pressures. Squeezing the teeth together is called clenching. Grinding the teeth together is called bruxing. Since none of these acts are part of the normal function of the stomatognathic system, they are called “Para function.” Based on the examination of over 4,500 patients in the metropolitan Los Angeles area during the past 14 years, Dr. Zadeh has discovered that an increasing number of individuals (about 6 out of every 10) are in danger of losing most or all of their teeth prematurely as the result of these “excessive forces.” In other words, the people who have healthy individual teeth have the potential of destroying their teeth through Para function by causing severe attrition, fracture, and/or necrosis of the teeth.
Para function takes place usually during sleep, totally unknown to the conscious mind. It is much like snoring, which takes place during sleep and stops upon awakening—the patient is completely unaware that the behavior has occurred, and is unable to stop it. The enamel that was meant to be in contact with the opposing enamel for only a few minutes during a 24-hour period is ground against the opposing enamel for 38.7 minutes (see Figure 2) during an 8-hour sleep period. The force of nocturnal bruxing is from 66% of maximum biting force to more than the maximum (see Figure 3). In more severe cases, it continues during the waking hours or while engaging in certain activities such as while reading or while lifting weights. On average, the duration of tooth-on-tooth contact is increased 8-fold while the force of this contact is at least doubled. In other words, the teeth are subjected to at least 16 times more wear in a person engaging in Para function than in a person who does not engage in Para function. Many individuals in their 20’s and 30’s who have totally worn out their enamel and have exposed the dentine (the second and much softer layer under the enamel) have come to Dr. Zadeh in the past for treatment. Much like periodontal disease, Para function is initially painless and progresses gradually and therefore is overlooked until the condition is quite advanced. The fact that all the teeth in the mouth are affected simultaneously and more or less to the same degree by this condition further complicates the consequences of Para function.
Figure2-various layers of tooth structure causing severe sensitivity
Causes of Para function in adults:
There have been many reasons given for grinding and clenching of the teeth. It would be safe to assume that in most cases, combination of two or more of these factors are responsible for the destruction of teeth. The scientific community has not yet discovered all of the factors involved.
- Structural triggers: Bite discrepancy is the basis that triggers grinding and clenching. There are two distinct mechanisms at work. Type I discrepancy is the discrepancy between the most comfortable position of the jaw joint and the most comfortable way that the teeth come together. Most people do have this bite discrepancy but not all of them grind or clench their teeth. This is the more common bite problem, but in absence of the second type of bite discrepancy, it usually does not cause much damage. Type II discrepancy results in absence of physiological guarding and feedback mechanisms that are naturally present in the front teeth. For the front teeth to provide this protection, the lower front teeth must be aligned in a certain close arrangement with the upper front teeth. When this “guarding” is not present, the back teeth can run into each other antagonistically in function and Para function, destroying each other.
- Psychological triggers: What makes this bite discrepancy become seriously detrimental is usually nervous tension. Stress makes the muscle fibers more responsive to the stimulation from the brain. Therefore the discrepancy, which is usually accepted by the body and does not elicit any significant response, brings out a strong reaction in presence of stress. People that engage in Para function may notice an increase in the frequency and severity of their clenching and/or grinding when they are under stress.
- Chemical triggers: Intake of “uppers” such as caffeine and amphetamines synergistically enhance the contractions of the jaw muscles. As a result, the use of these drugs can bring about rigorous clenching and grinding. Withdrawal from drug dependencies like nicotine and cocaine may also contribute to very harsh and callous clenching and grinding. It is not unusual to see these patients split an otherwise normal and healthy tooth (typically the lower first molar) in half, requiring immediate removal of the tooth to relieve the severe pain. Certain prescription drugs like the anti-depressant Zoloft are known to induce Para function as well.
- Habituation: It is important to realize that after years or even months of grinding and clenching, the act itself becomes a “habit”. Therefore, even if one reduces or eliminates all the above factors, one cannot expect to completely stop this behavior without addressing the habit itself.
Diagnosis of Para function
Much like the diagnoses of many other diseases, there are no “litmus tests” for this condition. Your dentist must make the final determination after considering all the factors and performing a thorough examination of your bite and jaw. The following factors are evidence that suggest presence of Para functional activity.
In an acute case: you may be going through an unusually stressful period of your life. It could be as trivial as preparing to leave for a vacation or moving to a different place, or as the loss of a loved one or a divorce.
- In the very acute form, most people are totally unaware of their nocturnal behavior and are given the news by their dentist when they go for an emergency toothache appointment! The dentist tells the patient that a tooth is cracked or fractured. The most common tooth involved is the most heavily restored tooth in the mouth, the lower first molar (see Figure 4).
Figure 4: Front to back fracture of the lower molar
- Waking up in the middle of the night and finding yourself clenching your teeth together is not uncommon.
- You may have morning headaches in the temporal areas.
- You may suffer from stiff neck and shoulders.
- You may find the teeth to be sore, especially upon awakening. You complain that “all” your teeth hurt.
If clenching becomes chronic and goes on for a long enough period of time:
- There may be cold and touch sensitivity associated with the neck of the teeth. Typically, the patient feels an “electric shock” sensation when he or she scratches the outside surface of the neck of the upper teeth with her nail. These areas are usually covered by gum but with chronic clenching, a condition called “abfraction” takes place. Abfraction is a condition in which the neck of the tooth is eroded away in a chemical reaction as it flexes under clenching and grinding forces. As a result of this, the dentinal surface becomes exposed and the area becomes extremely sensitive. The presence of the wedge-shaped erosions in a sensitive form is usually the evidence of clenching and grinding. If the person stops the clenching and grinding, the wedge-shaped spaces will remain, but the sensitivity will stop.
- Excessive wear facets which are flat and shiny on the top of the back teeth, inconsistent with the age of the individual, is a sign of grinding. Thinning and chipping of the front teeth is another sign of excessive wear from grinding.
- Formation of extra bone around the teeth, most commonly on the inside surfaces of the lower premolars. Previously, these bone formations, which are called “tori,” were thought to be of genetic origin.
- Clenching is usually associated with the outward pressing of the tongue on the teeth. This will leave the impression of the teeth as indentations on the sides of the tongue and is known as “scalloped tongue.” This is usually associated with a white line on the inside of the cheeks running parallel to the biting surfaces of the teeth.
Occasional periods of increased jaw muscle activity and Para function which are directly associated with short-lived stress do not usually have any long-term consequences.
However, if you suspect that you may be damaging your teeth on a regular basis, there are a number of steps that you can take to preserve your teeth.
- The first thing is to go to your dentist and let him or her confirm the diagnosis.
- Perhaps the most immediate, inexpensive, and effective way of stopping the damage and severity of grinding and clenching is through the use of a repositioning splint. A repositioning splint looks like the traditional night guard, but has certain special functions built into it. This device not only protects your teeth when you do grind, but in addition reduces your urge to grind. It does so by totally eliminating the Type I discrepancy previously discussed, and by incorporating the natural and physiological guarding and feedback mechanisms.
- If there is a bite discrepancy, your dentist can guide you in correcting the discrepancy. It is not always easy to correct the Type II discrepancies, nor is it necessary to correct every bite discrepancy. Treatment can range from selective grinding on some of the teeth to orthodontic treatment to jaw surgery, depending on the extent by which the front teeth are separated. In most cases where the separation is enhanced by the “wearing down of the tooth,” the lost enamel can be replaced, and the front teeth can be properly aligned by restorative materials. If the separation is within range, this method is highly effective, relatively easy, and free from adverse effects.
- In some cases, the costs, risks, and time involved for these procedures do not warrant attempting them. Correcting bite discrepancies takes very special skills, training, and instrumentation. In spite of numerous studies, in the absence of this preparation, some clinicians have gone as far as asserting that bite discrepancies are not related to Para function and jaw joint problems. They recommend supportive measures that will mostly help the patient in short term but have questionable long-term prognosis. However, this is much like leaving the offending nail in a flat tire and patching over it. These types of treatments are fine for short-term fixes or short-term problems, but are not recommended for those who have severe damage or who engage in long-term clenching or grinding.
- In a very acute stage and for a very short period of time like a few days, muscle relaxants prescribed by a dentist or physician can help with clenching and grinding.
- Psychological counseling can help when stressful stimuli cannot be self-controlled.
- Moist heat applications. Available from drug stores, these gels can be heated in a microwave oven and placed directly on the side of the face from the bottom of the jaw to the top of the head. Heat relaxes the muscles and therefore reduces their detrimental effects.
- Avoid “training” of the jaw muscles—avoid chewing gum. Chewing gum directly reduces the life of your teeth by wearing them many times faster than when you use your teeth only to chew your food. In addition, and even worse, repeated chewing of gum trains your jaw muscles to consistently clench and grind, so if you engage in Para function, you damage your teeth much more quickly.
- Neck exercises and neck and upper back massages. Para function fatigues the jaw muscles and puts them in spasm. Jaw muscles work antagonistically with the muscles of the back of the neck to balance the head. Relaxing and comforting one of these muscle groups often helps relax the other.
You can view before-and-after photos of clenching and grinding treatments in our photo gallery.
Dr. Zadeh and his staff will be happy to discuss preventing clenching and grinding with you. Please call for a consultation today.