Text I. Bruxism

Bruxism is grinding of the teeth. This is a habit observed in a large number of people occasionally, and in a smaller number, habitually. The mechanism of causation is tension and spasm of the muscles used for mastication.

Often, it occurs during sleep; even a short nap may induce it. In a typical case, the canines and incisors are commonly moved against each other laterally, i.e. a side to side action, which erodes tooth enamel, removing the sharp biting surfaces and flattening the edges of the teeth. Sometimes, there is a tendency to grind the molars together, which can be loud enough to wake a sleeping partner.

Over time, bruxing shortens and blunts the teeth being ground, and may lead to pain in the joint of the jaw, the temporomandibular joint, or headache. Teeth hollowed by previous decay (caries) may collapse; the pressure exerted by bruxism on the teeth is extraordinarily high.

The cause, or causes, of bruxism remain unclear. Some dentists believe it is due to a lack of symmetry in the teeth; others, that it reflects anxiety, digestive disturbances or a disturbed sleep pattern.

The effects of the condition may be quite advanced before sufferers are aware they brux. Eroded teeth may be brought to the sufferer's attention during a routine dental examination. If enough enamel is eroded, the softer dentine will be exposed, and erosion will accelerate. This opens the possibility of dental decay and tooth fracture, so early intervention by a dentist makes sense.

Treatment of bruxism

Sadly, there is no accepted cure as yet, mainly as we have no accepted model of causation for the condition. Ongoing management of bruxism is based on prevention of the abrasion of tooth surfaces by the wearing of an acrylic dental guard, created to the shape of the individual's upper teeth from a bite mould. This requires trips to the dentist for measuring and fitting. Alongside this full width guard, smaller and alternative shapes can be obtained, some with proprietary names.

If a tense jaw is experienced during wakefulness, some sufferers find it helpful to gently press their jaws open with fingertip pressure, to relax the affected muscles much as one would treat a leg cramp, but in this case, it is important to take care not to overextend the jaw joint.

Though, presently, there is no cure available for bruxers, it may be found beneficial to work at reducing stress and anxiety before bedtime, by a winding-down activity such as massage, meditation or reading, and eating early enough to ensure a fairly empty stomach at bedtime may also help.

Text II. Thumb-sucking and pacifier use may damage children's teeth

Many experts say children can safely suck their thumbs or pacifiers until they enter school, but a new study published in the December issue of the Journal of the American Dental Association suggests if the behavior persists after age two, children's bite may be affected.

"Sucking is a natural reflex, which comforts infants and young children. Any recommendation to stop thumb, finger or pacifier sucking before a child is two years old would be unrealistic, potentially detrimental and unnecessary from a dental standpoint," states lead author John J. Warren, D.D.S., M.S., of the University of Iowa College of Dentistry. Funding for the study was provided by the National Institutes of Health.

However, the study, conducted by Dr. Warren and colleagues at the University of Iowa College of Dentistry and the Tokyo Dental College, reveals that children who continue to suck a thumb, finger or pacifier past age two increase their risk of developing protruding front teeth. In addition, such habits increase the risk of an improper bite with narrowing of the upper jaw relative to the lower jaw (crossbite).

Dr. Warren's group studied 372 children in Iowa who sucked a thumb, finger pacifier, or combination thereof, from birth through age four. Each year, researchers administered questionnaires to the parents about their children's sucking habits.

At the end of the fourth year, the children were assigned to one of five groups, depending on the year they stopped the habit. The fifth group was made up of children who continued to suck their thumb, finger or pacifier. Models of the children's teeth were made between the ages of four to five and certain dimensions measured. Researchers then compared the measurements from each of the five groups.

Results indicate that the prevalence of crossbite in the molar area steadily increased from 5.8 percent for children who stopped the habit by one year of age, to 13 percent among children who stopped between two and three years old, to more than 20 percent for those who continued the habit after they turned four years old.

The researchers plan to continue the study to determine if the dental condition persists after the children's baby teeth are lost. In the meantime, Dr. Warren suggests that if three- to -four year old children persist in sucking their thumb, finger or pacifier, professional assistance may be needed to correct the resulting conditions.

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