Dentistry

Dentistry is the medical activity focused on treating the teeth, the gums and the oral cavity. This includes treating teeth damaged due to accidents or disease , filling teeth damaged due to tooth decay, and replacing damaged or injured teeth with replacement teeth. Major disciplines of dentistry include orthodontics, which focuses on the correction of tooth problems such as gaps between the teeth, crowded teeth and irregular bite; and periodontics, which addresses gum problems. Dentistry is considered an independent medical art, with its own licensing procedure. Medical doctors are not licensed to treat teeth; likewise dentists are not licensed to treat other parts of the body.

Skill and superstition

Ancient, medieval, and early Renaissance dental practice can be seen as a stew of the sensible and the outrageous. In each era, stories of practitioners with wisdom and skill coexist with outrageous tales of superstition and myth connected to teeth. In the ancient and Islamic worlds, doctors often performed dental work. The cleaning and extracting of teeth was often performed by individuals with little or no medical training.

Ancient men and women worked hard to alleviate dental pain . As early as 1550 b.c., the ancient Egyptians documented their interest in dentistry in the Ebers Papyrus, a document discovered in 1872. The Papyrus listed various remedies for toothache, including such familiar ingredients as dough, honey, onions, incense, and fennel seeds .

The Egyptians also turned to superstition for help preventing tooth pain. The mouse, which was considered to be protected by the Sun and capable of fending off death, was often used by individuals with a toothache. A common remedy involved applying half of the body of a dead mouse to the aching tooth while the body was still warm.

The Greeks offered a variety of conventional and unconventional dental therapy. One of the more illustrious dental pioneers was Hippocrates (460–375 b.c.), whose admonition to do no harm continues to be a central goal of medical practice. Hippocrates said that food lodged between teeth was responsible for tooth decay, and suggested pulling teeth that were loose and decayed.

Hippocrates also offered advice for bad breath. He suggested a mouth wash containing oil of anise seed and myrrh and white wine. Other ancient Greeks took a more superstitious approach, with some depending on the mythical power of the mouse to protect their teeth. A recipe for bad breath from the fifth century b.c. called for a range of ingredients including the bodies of three mice , including one whose intestines had been removed, and the head of a hare. The ingredients were burned and mixed with dust and water before consumption.

The Etruscans, who lived in Tuscany, Italy, between approximately 1000 and 400 b.c., also made great advances in dentistry. They are often cited for the sophistication of their gold crowns and bridges. One bridge which has been preserved included three artificial teeth attached to gold bands, which hooked around the natural teeth. The artificial teeth were actually real teeth taken from an immature calf, then divided in two.

The Romans built upon the Etruscan knowledge of dentistry and took seriously the challenge of keeping teeth healthy. Celsus, a Roman writer who lived about 100 b.c., wrote about toothache, dental abscesses and other dental ailments. For toothache, which he called "among the worst of tortures," he suggested the use of hot poultices, mouthwash, and steam. He also suggested using pain-killers such as opium. The Romans also made bridgework.

Clean teeth were valued by the Romans, and affluent families had slaves clean their mouths using small sticks of wood and tooth powder. Such powders could include burned eggshell, bay-leaves and myrrh. These powders could also include more unusual ingredients, such as burned heads of mice and lizard livers. Earth worms marinated in vinegar were used for a mouth wash, and urine was thought of as a gum strengthener.

The Romans, like individuals in many other cultures, believed that worms in the teeth caused pain. A vast well of superstition can also be found concerning the premature appearance of teeth. Babies born with one or more teeth were considered dangerous in Africa , Madagascar, and India, and were at one point killed. In contrast, the ancient Romans considered children born with teeth to be special, and children were often given a name, "Dentatus" in reference to their early dental development.

Non-western advances

Cultures outside Western civilization also focused on the teeth. The Chinese were the first to develop a silver amalgam filling, which was mentioned in medical texts as early as a.d. 659. The Chinese also developed full dentures by the twelfth century a.d. and invented the toothbrush model for our contemporary toothbrushes in the fifteenth century. Dental advances also flourished in the Islamic culture, which emerged around the spiritual and political power of Muhammad (570-632) and his followers. Innovators drew from the translated works of Aristotle, Plato, and Hippocrates, whose work was translated by Egyptians with links to Greece.

Mohammed's teaching called explicitly for the maintenance of clean teeth. Clean teeth were seen as a way of praising God, and he was reported to say "a prayer which is preceded by the use of the toothpick is worth 75 ordinary prayers." Dental powders, mouth wash, and polishing sticks were used to keep teeth clean.

Dental surgery advanced greatly with the teaching of Albucasis (936-1013), a surgeon whose extensive writing about surgery in the Al-Tasrif influenced Islamic and medieval European medical practitioners. He described surgery for dental irregularities, the use of gold wire to make teeth more stable, and the use of artificial teeth made of ox-bone. Albucasis also was one of the first to document the size and shape of dental tools, including drawings of dental saws, files, and extraction forceps in his book.

As the Islamic world moved ahead in dentistry, European dental practice was overwhelmed by the superstition, ignorance, and religious fervor of the Middle Ages. Scientific research was discouraged during the medieval era, which stretched from the fifth to the fifteenth century. Suffering and illness were widely considered to be punishment from God. Knowledge of dental anatomy and treatment did not advance during the Middle Ages, though the range of superstitious dental treatments flowered.

One fourteenth century therapy called for eating the brains of a hare to make lost teeth grow again. Charms made of stone, wood, or paper devoted to a religious figure were believed to ward off disease. Religious officials suggested prayer as the best protector.

The practice of dentistry during the Middle Ages was generally limited to the pulling of teeth that were decayed or destroyed. This task initially fell to barbers, who also performed minor surgery in England in the fifteenth century and were called barber-surgeons. Transient tooth-pullers, who traveled from place to place, also made money extracting teeth.

From counting teeth to replacing them

By the end of the fifteenth century, the emphasis on obedience to authority was changing, in part under the influence of advances such as the discovery of the printing press in 1436. Dentistry benefitted from the new spirit of inquiry. Contemporary thinkers, such as anatomist Andreas Vassalius (1514-1564) challenged classical ideas about dentistry. One indication of the stagnation of independent thinking was Vassalius's successful challenge of Aristotle's belief that men had more teeth than women.

Ambrose Pare (1510-1590), a Frenchman trained as a barber surgeon, gained fame as one of the great medical and dental surgeons of the era. His work resembled the work of a contemporary oral surgeon, focusing on the removal of teeth, the setting of fractured jaws and the draining of dental abscesses. He published extensively, documenting methods for transplanting teeth and for creating devices that held artificial teeth made of bone in place using silver or gold wire.

The eighteenth century saw many significant advances in dentistry, many of them inspired by the work of Pierre Fauchard (1678-1761). By the year 1700, Parisian dentists such as Fauchard were considered members of a distinct profession, complete with an examining board for new dentists. Fauchard's work is best known through his writing about the profession in the 1728, two-volume, Le Chirurgien Dentiste, a 863-page tome. In the book, Fauchard explained how to fill teeth with lead or gold leaf tin foil, and various types of dentures. He also told how to make crowns from ivory or human teeth, how to straighten teeth, and how to protect teeth against periodontal damage.

Fauchard also took aim at some of the dental superstitions of the day, which included the erroneous belief that worms in the mouth played a role in tooth decay. His information was not all accurate, however, and Fauchard did suggest the use of urine as a mouth wash.

Another great eighteenth century finding was the development of porcelain, glazed white clay, as a substance for false teeth. Prior to this time, ivory was commonly used. Carving ivory was time consuming and difficult. The first porcelain teeth were developed by M. DeChateau, a French druggist, and M. Dubois De Chamant, a dentist.

DeChateau was frustrated that his teeth had discolored due to the chemicals he tasted while mixing substances for customers. After noticing that the chemicals never discolored his porcelain mortar and pestle, DeChateau decided that porcelain teeth would save him embarrassment and unhappiness. Gaining the help of DeChamant, the two men discovered a way to effectively fit and create a pair of false teeth made of porcelain, gaining a patent on the teeth in 1788.

The nineteenth century saw the development of many dental tools and practices that would be the bedrock for twentieth century dentistry. Many of the great advances were made by Americans, who emerged as great dental innovators. The world's first dental school, the Baltimore College of Dentistry, opened in 1847, providing an organized curriculum to replace the apprenticeship system.

At the start of the century, false teeth were available to only the affluent. They were made of porcelain, which was not expensive. But they needed to be fastened to plates made of gold or silver, which were costly. The successful vulcanization of rubber in 1830 by American Charles Goodyear brought cheap false teeth to the masses. Now false teeth could be attached to vulcanized rubber, and dental laboratories emerged everywhere to keep up with the demand.

The development of anesthesia in the United States was a technological breakthrough which revolutionized surgical and dental practice. Many innovators experimented with the use of gases in the eighteenth and nineteenth centuries. Joseph Priestley, a British cleric, invented nitrous oxide, or laughing gas, in 1772. The substance caused euphoria, then sedation and unconsciousness.

Though researchers explored the application of nitrous oxide and ether in the early nineteenth century, the gases were not used for anesthetic purposes until the 1840s. Physician Crawford Williamson Long, a Georgia physician, first used ether to remove a tumor from a patient in 1842. Dentist Horace Wells used nitrousoxide on patients having their teeth pulled in 1844.

But dentist William Thomas Green Morton is widely credited with the first public display of anesthesia, in part because of the great success of his public demonstration and in part because of his canny alliance with influential physicians. Morton successfully extracted a tooth from a patient anesthetized with ether in 1846 in Boston.

Ether, nitrous oxide and chloroform were all used successfully during tooth extraction. But these gases were not effective for many other procedures, particularly those which took a long period of time to complete.

A breakthrough came in the form of the drug cocaine , an addictive drug derived from coca leaves which was highly valued in the nineteenth and early twentieth centuries for its pain-killing power. In 1899, cocaine was first used in New York as a local anesthetic to prevent pain in the lower jaw. Cocaine was effective but habit-forming and sometimes harmful to patients. The development of procaine, now known as novocaine, in 1905 provided dentists with a safer anesthetic than cocaine. Novocaine could be used for tooth grinding, tooth extraction and many other dental procedures.

Development of a drill powered by a footpedal in 1871 and the first electric drill in 1872 also changed the practice of dentistry.

Another major discovery of the era was the x ray by William Conrad Roentgen of Germany in 1895. The first x ray of the teeth was made in 1896. At the time, there was some skepticism about x rays . The Pall Mall Gazette of London railed in 1896 about the "indecency" of viewing another person's bones. William Herbert Rollins of New England reported as early as 1901 that x rays could be dangerous and should be housed properly to prevent excess exposure. Contemporary dentists continue to use x rays extensively to determine the condition of the teeth and the roots.

Modern dentistry

Cavities and fillings

The great nineteenth century advances in dentistry provided dentists with the tools to repair or remove damaged teeth with a minimum of pain. The hallmarks of dentistry in the twentieth century have been advances in the preservation of teeth.

The success of these efforts can be seen in the fact that more older Americans retain their teeth. For example, the number of Americans without teeth was 18 million in 1986, according to the Centers for Disease Control. By 1989, the number had dropped to 16.5 million. Children also have fewer dental caries, the technical name for cavities. While nearly three quarters of all 9-year-olds had cavities in the early 1970s, only one-third of 9-year-olds had cavities in the late 1980s, according to the Centers for Disease Control.

But many dental problems and challenges still exist. The two most common types of oral disease are dental caries and periodontal disease, Rowe reports. Dental caries stem from the destruction of the tooth by microbial activity on the surface. Dental caries occur when bacteria forms a dental plaque on the surface of the tooth. Plaque is a deposit of bacteria and their products which is sticky and colorless. After the plaque is formed, food and the bacteria combine to create acids that slowly dissolve the substance of the tooth. The result is a hole in the tooth which must be filled or greater damage may occur, including eventual loss of the tooth.

Many different strategies exist to prevent dental caries. These include the reduction of sugar consumption. While some foods, such as starches, do not digest completely in the mouth, other foods, such as sugars, break down quickly in the mouth and are particularly harmful. Tooth brushing also helps reduce plaque. Other preventive techniques, such as the use of fluoride and sealants, are also helpful.

Fluoride was recognized as early as 1874 as a protector against tooth decay. Great controversy surrounded the addition of fluoride to the public water supply in many communities in the 1950s and 60s, as concerns were raised about the long-term health affects of fluoride. While controversy on the issue remains in some areas, public health experts suggest that fluoride has greatly improved dental health in young and old people. The number of cavities are reduced 65% in areas in which water is fluoridated.

Another advance was the development of sealants for children in the late 1960s. These sealants, made of a clear plastic material, are typically added to an etched tooth surface to protect the tooth from decay. They can protect teeth from cavities for up to 15 years. They are generally used on the chewing surfaces of back teeth, which are most prone to tooth decay. Sealants are currently recommended for all children by the American Dental Association.

Regular dental check-ups are used to monitor teeth and prevent dental caries from growing large. Contemporary dentists typically examine teeth using dental equipment to poke and probe teeth and x rays to see potential dental caries before they can be seen easily without aid. To detect problems, x-ray beams are focused on special photographic film placed in the mouth. The x rays create a record of the tooth, with the film documenting dental cavities or other problems in the tooth.

The process of fixing dental caries can be a short procedure depending on the size of the cavity. Small cavities may require no anesthesia and minimal drilling, while extensive dental caries may require novocaine or nitrous oxide to dull the pain and extensive drilling. Typically the process of filling a cavity begins with the dentist using a drill or a hand tool to grind down the part of the tooth surrounding the dental carry. The dentist then shapes the cavity, removes debris from the cavity, and dries it off. At this point a cement lining is added as to insulate the inside of the tooth. The cavity is filled by inserting an amalgam or some other substance in small increments, compressing the material soundly.

Teeth are usually filled with an amalgam including silver, copper , tin, mercury, indium, and palladium. Other materials may be used for front teeth where metallic fillings would stand out. These include plastic composite material, which can be made to match tooth color .

Controversy about the possible safety hazards of mercury in amalgam fillings led some Americans to have their amalgam fillings removed in the early 1990s. While mercury is a proven toxic chemical, there is no proof that mercury in amalgam fillings causes disease, according to the American Dental Association. Still, some experts suggest that dentists seek alternatives to mercury to combat potential problems and fear linked to mercury exposure.

Tooth replacement

Teeth that have large cavities, are badly discolored, or badly broken often are capped with a crown, which covers all or part of the crown, or visible portion, of the tooth. This can be made of gold or dental porcelain. Dental cement is used to keep the crown in place.

Bridges are created when individuals need some tooth replacement but not enough to warrant dentures, which offer more extensive tooth replacement. These devices clasp new teeth in place, keep decayed teeth strong, and support the teeth in a proper configuration. Missing or damaged teeth may lead to difficulty speaking and eating. Like bridges for rivers or streams, dental bridges can be constructed many different ways, depending on the need and the area that needs bridging. There are cantilever dental bridges and many other types. Some are removable by the dentist, and may be attached to the mouth by screw or soft cement. Others, called fixed bridges, are intended to be permanent.

Dentures, a set of replacement teeth, are used when all or a large part of the teeth must be replaced. New teeth can be made of acrylic resin or porcelain. Creating a base to set the teeth in is an ambitious undertaking, requiring the development of an impression from the existing teeth and jaws and the construction of a base designed to fit the mouth exactly and not add errors. Contemporary dentists generally use acrylic plastics as the base for dentures. Acrylic plastic is mixed as a dough, heated, molded, and set in shape.

Gum disease and bad breath

Gum disease is an immense problem among adults. The more common gum diseases, gingivitis, can be found in about 44% of all employed Americans 18–64. Periodontitis can be found in at least 14% of this group, though it and gingivitis is far more common among older people. Gingivitis is the inflammation of gum tissue , and is marked by bleeding, swollen gums. Periodontitis involves damage to the periodontal ligament, which connects each tooth to the bone. It also involves damage to the alveolar bone to which teeth are attached.

Untreated periodontal disease results in exposure of tooth root surfaces and pockets between the teeth and supporting tissue. This leaves teeth and roots more susceptible to decay and tooth loss.

Periodontitis and gingivitis are caused primarily by bacterial dental plaque. This plaque includes bacteria which produce destructive enzymes in the mouth. These enzymes can damage cells and connective tissue . To prevent gum disease from forming, experts suggest regular brushing, flossing and removal of bacterial plaque using various dental tools. Regular mechanical removal of plaque by a dentist or hygienist is also essential.

Periodontal surgery is necessary when damage is too great. During this procedure, gums are moved away from bone and teeth temporarily to allow dentists to clean out and regenerate the damaged area.

Another less serious dental problem is halitosis, or bad breath. Bad breath can be due to normal body processes or to illness. Halitosis early in the morning is normal, due to the added amount of bacteria in the mouth during sleep and the reduced secretion of saliva, which cleanses the mouth. Another normal cause of bad breath is when one is hungry. This occurs because the pancreatic juice enters the intestinal tract when one has not eaten for some time, causing a bad smell . Certain foods also cause bad breath, such as garlic, alcohol , and fatty meat, which causes halitosis because the fatty acids are excreted through the lungs.

Halitosis can also be caused by a wealth of illnesses, ranging from diabetes to kidney failure and chronic lung disease. Dental problems such as plaque and dental caries can also contribute to bad breath. Treatment for the condition typically involves treating the illness, if that is causing the problem, and improving oral hygiene. This means brushing the tongue as well as the teeth.

Orthodontics: the art of moving teeth

The practice of orthodontics depends on the fact that the position of teeth in the mouth can be shaped and changed gradually using pressure . Orthodontia is used to correct problems ranging from a bite that is out of alignment, to a protruding jaw, to crowded teeth. Typically orthodontia begins when individuals are in their early teens, and takes about two years. However, with the development of clear plastic braces, adults are increasingly likely to turn to orthodontia to improve their appearance, and make eating and talking more comfortable.

The process may require some teeth to be pulled. The removal of teeth allows for the growth of other teeth to fill the newly-vacant area. Braces are made up of a network of wires and bands made of stainless steel or clear plastic. The tubes are often anchored on the molars and the wires are adjusted to provide steady pressure on the surface of the teeth. This pressure slowly moves the tooth to a more desirable location in the mouth and enables new bone to build up where it is needed. Orthodontia can also be used to help move the jaw by anchoring wires to the opposing jaw.

A look forward

Laser beams are already used in dentistry and in medical practice. But lasers are currently not used for everyday dentistry, such as the drilling of teeth. In the future, as laser technology becomes more refined, lasers may take the place of many conventional dental tools. Using lasers instead of dental tools would cut down on the opportunity to be exposed to blood-borne illness, and reduce damage to surrounding tissue.

Researchers also are exploring new ways to treat periodontal disease, such as more specific antibacterial therapy and stronger antibacterial agents. Many researchers also see a stronger role for fluoride in the future, in addition to its current presence in many public water supplies. Some dentists advocate the use of fluoride in sealants. A 1991 study reported that a sealant including fluoride reduced tooth irritation for some individuals with sensitive teeth.

While dentistry has made immense progress since days when a dead mouse was considered high dental technology, there is still progress to be made. Future challenges for the dental profession include continuing to reduce tooth loss and decay due to neglect and the aging process.

Resources

books

Aschheim, Kenneth W., and Barry G. Dale. Esthetic Dentistry:A Clinical Approach to Techniques and Materials. 2nd ed. St. Louis: Mosby, Inc., 2001.

Hupp, James, and Larry J. Peterson. Contemporary Oral andMaxillofacial Surgery. 4th ed. St. Louis: Mosby, Inc., 2002.

Proffit, William, and Henry W. Fields. Contemporary Orthodontics. 3rd ed. Chicago: Year Book Medical Publishing, 2000.

Roderick, Cawson, and William Binnie, Anderw Barrett, and John Wright. Oral Disease. 3rd ed. St. Louis: Mosby, Inc., 2001.

periodicals

Gift, Helen C., Stephen B. Corbin, and Ruth E. Nowjack-Raymer. "Public Knowledge of Prevention of Dental Disease." Public Health Reports 109, 397. (May-June 1994).

"What Will the Future Bring?" Journal of the American DentalAssociation 123. (April 1992): 40-46.

Patricia Braus

KEY TERMS

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Abscess

—An enclosed collection of liquefied tissue, known as pus, somewhere in the body.

Bridge

—Replacement for a missing tooth or teeth which is supported by roots or natural teeth.

Gingivitis

—Gum inflammation

Vulcanization

—A process in which sulfur and raw latex are combined at a high temperature to make rubber more durable.