Dentistry has come a long way from when the only permanent remedy for a toothache was to have the tooth yanked out without an anaesthetic. If you couldn't face this, the only alternative professional prescription was to gargle with urine.
According to an article by Robert Genco and others in the November/December 2000 edition of The Sciences, the future of dental practice will be as different from today's dentistry as today from the distant past.
If an 80-year-old man and his 40-year-old daughter went for a dental examination today the results would summarise the history of dental care over the 20th century. The father's mouth would show a lifetime of tooth extractions, gum disease, cavities and root canal treatments. Dentures, implants and bridges would be prominent, and the few remaining teeth would probably wear golden crowns.
The daughter would retain all her natural teeth, although some would be marked by silver fillings. She would show some evidence of gum disease that was diagnosed early and treated so it is unlikely to cause future loss of teeth.
People have always suffered from tooth decay. The cause is plaque: a sticky film of bacteria that coats teeth and gums. These bacteria live off sugar residues that remain after we eat carbohydrates. They ferment the sugar into lactic acid which eats into the enamel surface of teeth, creating cavities.
Gum disease is a persistent infection also caused by plaque bacteria. In its early stages the gum becomes red and swollen and bleeds easily. Later pockets form between the gum and the teeth allowing bacteria to burrow beneath the gum line. The corrosive action deepens the pocket, and eventually gum disease can eat away at the jawbone until the teeth fall out.
Therefore the practice of dental hygiene is to daily remove bacterial plaque by careful brushing and flossing.
The indirect action of oral bacteria on teeth and gums can be even worse. When gums are infected the body mounts an immune attack. Specialised cells are mobilised to attack and kill the bacteria, releasing enzymes that digest the bacteria.
One of these enzymes attacks collagen, a vital structural component of bone, cartilage and ligament. Therefore in prolonged gum infection, the victim's own immune system starts to break down the mouth tissue.
One principal reason why the 80-yearold father's teeth are so much worse than his daughter's is the daughter's lifetime ingestion of fluoride. It was discovered in 1942 that fluoride in drinking water could fortify tooth enamel against bacterial acid. Fluoride is now routinely added to tap water, toothpaste and mouth rinses and, as a result, the present generation is probably the first to keep all its teeth throughout old age.
The mouth hosts a huge diversity of bacteria - over 500 species have been identified. Some of these are beneficial, some are benign, but about one-third are harmful. Dealing selectively with the harmful bacteria is difficult so the dentist simply scrapes the teeth clean and occasionally prescribes antibiotics to deal with acute infection.
However, in the future dentists will be able to pinpoint harmful bacteria with DNA tests and kill them with specific antibiotics to which they are susceptible. Eventually it should be possible to vaccinate patients against cavities and gum disease.
We each grow two sets of teeth in a lifetime, baby teeth and adult teeth. Unfortunately, if you lose an adult tooth you cannot grow a replacement. This may become possible eventually. American researchers have succeeded in growing mouse teeth in a Petri dish, and this work may progress to human teeth.
However, at present the best to be hoped for in serious gum disease is to slow down or stop tissue destruction. A new drug, Periostat, kills oral bacteria and also inhibits the enzyme collagenase that can cause so much damage.
The American Surgeon-General has just announced that the state of the mouth is an early warning of broader medical problems. Many illnesses aggravate gum disease. AIDS, cigarettes, stress and diabetes increase the risk of gum disease. Osteoporosis thins bones and makes the jawbone more susceptible to attack by bacteria.
The situation also works in the other direction - gum disease can cause a decline in general health. It is thought that when gums bleed, oral bacteria can enter the bloodstream and trigger ill-effects elsewhere in the body. The work of today's dentist is largely excavation and construction, but this will change greatly. Treatment with antibiotics and immunisation against cavities and gum disease should ensure that all who can afford dental treatment will have lifelong healthy mouths.
Treating and preventing gum disease will become an important step in maintaining general health. Half of the risk of contracting gum disease is attributable to smoking. Dentists will be involved in enrolling patients in programmes to help them quit the habit. They will screen patients for heart disease and test saliva for indicators of many diseases elsewhere in the body.
This changed role will see the dentist enter the general medical fold to a much greater extent than at present. The public can look forward to a future free of dental pain and tooth loss.
William Reville is a senior lecturer in biochemistry and director of microscopy at UCC