By Dr Bertrand Stuart, DDS
THUMB-sucking is a common habit of preschool children. The activity is normal for infants and toddlers, but should decrease by three years and stop totally by age four. Unfortunately, many youngsters can’t break the habit by this time. But is parental anxiety over thumb-sucking warranted? It should be, if the right attitude is not embraced.

The sucking of the thumb, another finger(s), or the tongue is a very normal response to anxiety and stress and does not point to insecurity or emotional problems in your child. However, most children give up the habit by age four, when some children continue to suck their thumbs as a means of exerting independence. I know a woman aged 52 who has confessed to me that she still sucks her thumb. Aside from some minor problems with thumb and fingernail infections, the most damage from thumb-sucking occurs to the teeth and jaw.

A well-known pediatrician recently stated on television that continued sucking of thumbs or fingers does not cause serious dental problems in children and is not cause for parental alarm. Wrong! In fact, prolonged thumb activity produces significant problems with chewing, speech, and facial appearance. In fact, the more time a child sucks his/her thumb and the greater the sucking pressure, the more harm done to teeth and jaws. Day and night forceful thumb-sucking makes front teeth move, and can even reshape the jaw bone. Upper front teeth flare out and tip upward, while lower front teeth move inward. But, how can something as small as a child’s thumb or finger effectively move bone?

The reason that thumbs and fingers are effective tooth-movers and bone shapers is that the jaw bones of children under age eight are especially soft and malleable. Children have upper and lower jaws rich in blood supply and relatively low in mineral content, especially calcium. Unfortunately for children and parents, prolonged thumb or finger sucking easily deforms the bone surrounding upper and lower front teeth, producing a hole or gap when teeth are brought together known as an ‘open bite’. Now, if a child stops thumb-sucking before loss of baby front teeth and permanent front tooth eruption, most or all harmful effects disappear within six months. However, if the habit persists through permanent front tooth eruption, there can be lasting damage: flared or protruded upper teeth, delayed eruption of upper or lower front teeth, and the aforementioned open bite. This can result in chewing difficulties, speech abnormalities, and an unattractive smile.

Some parents try home remedies to break the habit. Some try placing gloves on their children before bedtime. Others paint thumbs and fingers with various foul-tasting substances, while still others wrap bandages around the offending digits. Yet all of these measures are typically easy to overcome and are usually unsuccessful, because thumb-sucking is a deeply ingrained behaviour. One method which might help is to tie/roll a used x-ray film on the elbow of the child so that child cannot bend the hand. You can tape the edges of the film to avoid sharp ends. Any method will work, but only if child agrees to cooperate.

One answer to this parental dilemma is a simple device called a ‘crib’. Placed by your dentist on the child’s upper teeth, the crib usually stops the habit cold the first day of use. The appliance’s technical name is a ‘fixed palatal crib’, and is a type of brace that sits full-time on the upper teeth and the roof of the mouth. The crib consists of semicircular stainless steel wires connected to supporting steel bands or rings. The half-circle of wires fits behind the child’s upper front teeth, barely visible in normal view. The bands are fastened to the baby upper second molars. There are a number of different crib designs used by dentists, all variations on the same theme.

The first step for parents is to make an appointment for their child with a dentist. At the initial visit, the doctor examines the child for problems with tooth position and bite. The teeth of confirmed thumb-suckers have the tell-tale pattern described above, and the doctor will ask about any habit history. With a diagnosis of intractable thumb-sucking, the dentist will usually recommend a crib to eliminate the habit. A second appointment is then arranged, where clay impressions are made for plaster study models, together with facial and dental photographs and jaw x-rays.

The dentist generally begins crib construction at the third visit, and installs the appliance at the fourth. The child may or may not experience soreness of the upper back teeth for a few hours, and modified speech for one or two days. Instructions are given on avoiding gum-chewing, hard and sticky candy, popcorn, peanuts and other brace-destroying foods. The patient is asked not to pull on the crib with fingers. Thorough tooth-brushing after each meal is stressed to prevent food and plaque build-up and gum infections or cavities.

Once the crib is installed, there is little adjustment. It is one of the simplest, yet most effective orthodontic devices. Terrible looking open bites can close within a few months. The parent and patient should consult the dentist every two weeks, so that proper monitoring can take place. One should remember that if the habit of thumb-sucking is not arrested at the right time, then the parent can easily find themselves paying over a hundred thousand dollars to correct the problem.