physiologically normal activation of voluntary muscles to produce behaviours that lack functional purpose and are potentially injurious. To be considered normal , when chronically repeated these behaviours lead to occlusal disorders. Examples of parafunctional behaviour are Bruxism ( Grinding and Clenching ), thumb sucking and abnormal jaw posturing

Bite discrepancy:

      - Type I : the most comfortable position of the jaw joint and the most comfortable way that the teeth come together are different. Most people do have this bite discrepancy but not all of them grind or clench their teeth in absence of the second type.
     - Type II : when the physiological guarding and feedback mechanisms of the front teeth is lacking. 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 is missing, the back teeth can run into each other in function and Parafunction, destroying each other.

Nervous tension:
Stress makes the muscle more responsive to the stimulations. Therefore the already mentioned discrepancy, which is usually accepted by the body and does not elicit any significant response, brings out a strong reaction in presence of stress.


such as caffeine and amphetamines synergistically enhance the contractions of the jaw muscles. Hence the use of these drugs can bring about rigorous clenching and grinding. Drug dependencies like nicotine and cocaine is also to be blamed. These patients can split an healthy tooth (typically the lower first molar) in halves requiring immediate removal of the tooth to relieve the pain. Certain prescription drugs like some antidepressant can induce parafunction.


after a period of grinding and clenching, the act itself becomes a “habit”. Therefore, even reducing or eliminating all the above factors, this behavior cannot be stopped, without addressing the habit itself.

Signs  and Sintoms


  • Most people are totally unaware of their nocturnal behavior and are given the news at their emergency toothache appointment! The tooth mainly involved is the most heavily restored tooth in the mouth, the lower first molar, cracked or fractured.
  • Waking up in the middle of the night and finding yourself clenching your teeth togheter.
  • Morning headaches in the temporal areas.
  • Stiff neck and shoulders.
  • Sore teeth, especially upon awakening. Complain that “all” teeth hurt.


  • Cold and touch sensitivity of the neck of the teeth affected by abfraction
  • Wear facets, flat and shiny on the top of the back teeth, inconsistent with the age of the individual.
  • Thinning and chipping of the front teeth.
  • Formation of extra bone around the teeth, most commonly on the inside surfaces of the lower premolars. Due to their very slow formation, patients are never aware of the presence of such growths.
  • Clenching is usually associated with the outward pressing on the teeth by the tongue. This will leave the impression of the teeth as indentations on the sides of the tongue and it is called “scalloped tongue”. A white line on the inside of the cheeks running parallel to the biting surfaces of the teeth is also commonly present.
  •  A repositioning splint or a nightguard with added functions able to eliminate type I discrepancy and to provide protected function, is the most immediate and effective mean to stop the injuries of parafunction, also the least expensive.
  • It is not always easy ( neither always necessary ) to correct the Type II discrepancies. The treatment can range from selective grinding on some of the teeth to orthodontic treatment to surgery, depending on the extent by which the front teeth are separated.

    -        In most cases, the lost enamel can be replaced and the front teeth properly aligned by restorative materials. If the separation is within range, this method is highly effective, relatively easy and free from any adverse effects.
  1. In some cases, the costs, risks and time involved for these procedures do not warrant attempting them. Is recommend to provide supportive measures that will mostly help the patient in short  medium term
  2. In a very acute stage, for a very short period of time, muscle relaxants prescribed by a dentist or physician can help.
  1. Psychological counseling can help when stress cannot be self-controlled.
  2. Moist heat applications. Available from drug stores, these gels can be heated in microwave oven and placed directly on the side of the face from bottom of the jaw to top of the head. Heat relaxes the muscles and therefore reduces their detrimental effects.
  3. 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 to chew your food with. In addition and even worse, it trains your jaw muscles and when you engage in parafunction, you damage your teeth many times faster.
  4. Neck exercises and neck and upper back massages. parafunction fatigues the jaw muscles and puts them in spasm. Jaw muscles work anta-agonistically with muscles of back of the neck to balance the head. Relaxing and comforting of one of these muscle groups, helps relax the other.