DENTISTRY

DENTISTRY. In the eighteenth century, the practice of dentistry was primarily concerned with extracting diseased teeth, not protecting healthy ones. When George Washington was inaugurated in 1789 at the age of 57, he had only one natural tooth left. State-of-the-art dental care in his day consisted of yanking out rotten teeth without benefit of painkillers and crafting awkward dentures from elk and cow teeth, and from the ivory tusks of elephants, hippopotami, and walruses. (Washington owned several pairs of such dentures, though none made of wood, despite the myth.) Dr. A. A. Plantou, a Frenchman who had emigrated to Philadelphia, introduced porcelain teeth to the United States in 1817. (France was the center of dentistry in the eighteenth century; American dominance in the field began in the nineteenth century.) In the 1850s, Nelson Goodyear's invention of Vulcanite—an inexpensive hard rubber that could be molded to the shape of the jaw and fitted with porcelain teeth—finally made false teeth affordable for the average person.

The introduction of nitrous oxide ("laughing gas") in the early 1830s made extraction less painful, but correct dosages were hard to determine. Ether was first used in surgery in 1842 by Dr. Crawford W. Long (though the patent went to Drs. William Thomas Green Morton and Charles Thomas Jackson in 1846). Chloroform, discovered in the early 1830s by doctors in several countries, also began to be used as an anesthetic in dentistry. In 1884, Dr. William Stuart Halsted reported that morphine injected into the lower jaw resulted in complete numbness in six minutes. However, the drug was addictive and could cause localized tissue death (necrosis). It wasn't until 1905 and the invention of the first non-addictive anesthetic, novocaine ("new cocaine"), that dental work could be both safe and painless.

In 1855, Dr. Robert Arthur introduced a cohesive gold foil filling for teeth, produced by heating and cooling the metal to make it stronger. The first crowns were developed in 1880 by Dr. Cassius M. Richmond, who patented a porcelain tooth soldered to a gold body. The invention of the electric furnace (in 1894) and low-fusing porcelain (in 1898) made possible the first strong porcelain "jacket" crown, introduced in 1903.

The first dental school, the Baltimore College of Dental Surgery, was founded in 1840 in Maryland. For decades, however, dentists were not required to pass a test or obtain a license in order to practice. It took nearly one hundred years for dental education to develop its present form: three or four years of undergraduate study and four years of dental school, with a curriculum including medical science, technical training, and clinical practice.

The Mercury Controversy

Mercury compounds introduced to the United States in 1832 as a filling for the cavities left after dental caries are removed provoked a controversy that continues to the present day. Because the injurious effects of mercury poisoning—ranging from muscle tremors to hallucinations— were well known in the nineteenth century, many were fearful of the new treatment. Mercury still accounts for 50 percent of modern silver amalgam fillings, developed in 1895 by Dr. G. V. Black (known as "the father of scientific dentistry"). The other components are: 35 percent silver, about 15 percent tin (or tin and copper, for added strength), and a trace of zinc. In the late 1980s it was discovered that minute amounts of mercury vapor are released in chewing. A few years later researchers demonstrated the ill effects of silver amalgam in sheep (the mercury caused kidney malfunction) and human fetuses (mercury from mothers with silver fillings was found in the brain tissue of stillborn babies). Some worried patients have had all their amalgam fillings removed and replaced with porcelain inlays (developed in the late 1890s) or composite resin fillings (invented in the late 1930s). On the other hand, considering the long and widespread use of amalgam fillings—contained in the teeth of more than 100 million living Americans, and handled constantly by dentists—many experts believe such findings to be inconclusive. The American Dental Association (ADA) not only affirms the safety of dental amalgam but also claims that it is unethical for dentists to recommend removal of amalgam fillings from a patient's teeth "for the alleged purpose of removing toxic substances from the body." The ADA cites other studies, of dentists as well as patients, that show no correlation between amalgam fillings and kidney disease or nervous disorders.

Treating Tooth Decay

In the early nineteenth century, it was believed that decay (dental caries) originated on the surface of the tooth. In 1890, American dentist Willoughby D. Miller's ground-breaking work, The Micro-organisms of the Human Mouth, revealed that acids from dissolved sugars in foods decalcify tooth enamel, followed by bacterial action that destroys the bone-like dentin underneath that surrounds living tissue. This discovery led dentists to place more emphasis on oral prophylaxis—disease-preventive measures—as well as on proper sterilization of dental tools. Yet dental health nationwide remained less than optimum. During World War II, the Selective Service initially required each new armed forces recruit to have at least twelve teeth, three pairs of matching front teeth (incisors) and three pairs of chewing teeth (molars). When it turned out that one in five of the first two million men didn't qualify, all dental standards were dropped.

The addition of fluoride to city water systems, beginning in 1945 in Michigan and Illinois, sparked a major controversy. In 1942, a U.S. Public Health Service dentist, Dr. H. Trendley Dean, had determined that adding one part fluoride per million of drinking water reduced dental caries. By 1950, more than 50 cities had fluoridated their water supply. Then came the protests, most famously those of the John Birch Society, which believed the program to be a Communist plot to poison Americans. Others, including health food advocates, were concerned about potential poisons. Yet by the 1960s fluoride was in nearly 3,000 water systems serving 83 million people. By the end of the twentieth century, some 155 million Americans—62 percent of the population—had fluoridated water. Fluoride also has been added to many toothpaste and mouthwash brands.

In 1954 a team of scientists at the University of Notre Dame, led by Frank J. Orland, identified Streptococcus mutans as the bacteria that produces the acid that dissolves tooth enamel and dentin. The origin of gum (periodontal) disease was unknown until the mid-1960s, when bacterial plaque was found to be the culprit. Since the 1970s, biotechnology has helped the dental researchers known as oral ecologists to begin to identify some of the more than 400 species of microorganisms (mostly bacteria) that live in the mouth.

Dental Tools

Invented in 1895 in Germany, x-rays were demonstrated for dental use the following year in the United States by Dr. Charles Edmund Kells Jr., who also invented the automatic electric suction pump to drain saliva. (The first tool for saliva control was the rubber dental dam, invented in 1864 by Dr. Sanford C. Barnum.) Commercial x-ray equipment made for dentistry was first used in the United States in 1913. Other features of modern dental offices took many decades to achieve their present form. In 1832 James Snell developed the first dental chair, which included a spirit lamp and mirror to illuminate the patient's mouth. A major breakthrough in chair design occurred in 1954, with Dr. Sanford S. Golden's reclining model. John Naughton's Den-Tal-Ez chair, powered by hydraulic cylinders, was introduced in the 1960s. The first self-cleaning device to receive patients' spit was the Whitcomb Fountain Spittoon, marketed in 1867.

The electric-powered drill was invented in 1868 by George F. Green, a mechanic employed by the S. S. White Company. Inspired by the workings of the Singer sewing machine mass-produced a decade earlier, James Beall Morrison added a foot treadle and pulley system in 1871. But the drill was still very heavy, and dentists' offices were not wired for electricity until the late 1880s, when Dr. Kells first adopted the new technology. In 1953 a team at the National Bureau of Standards, led by Dr. Robert J. Nelson, finally developed a hydraulic-powered turbine drill that could achieve speeds of 61,000 revolutions per minute. (Today, electrically powered drill speeds of 400,000 revolutions per minute or more are common.) Speed is significant because it reduces not only the time it takes to remove caries but also the amount of pressure on the tooth.

Recent Developments

Since the mid-1980s composite resin fillings have grown increasingly popular in the United States as an alternative to amalgam. The first composite filling was developed in 1955 by Michael Buonocore and others, but the acrylic proved too soft for the stress caused by chewing. The addition of microscopic particles of glass or quartz to the plastic resin base in 1967 solved this problem. While composite resin is white—and therefore relatively invisible—it is not as long-lasting as silver amalgam, can be more costly for the patient, and requires greater skill on the dentist's part because it is applied in separate layers that must harden under a strong light.

Numerous advances in dental treatment in the late twentieth century have radically altered the field. Digital imagery of the teeth, transmitted through fiber optics from an x-ray sensor to a computer screen, offers a faster, safer, and more easily readable alternative to x-ray film. This process emits 90 to 95 percent less radiation than ordinary x-rays, and allows the image to be magnified and more easily stored, reproduced, and shared with other doctors. The first laser "drill" was approved by the FDA in 1997. Lasers burn through decay without vibration or pressure on the tooth. Other advances include "invisible" braces that attach to the insides of teeth, dental implants that anchor to the jaw to permanently replace missing teeth, and computer-generated tooth restorations. Cosmetic dentistry, including bonding (using composite resin to improve tooth shape and whiteness) and bleaching, has spawned business franchises devoted exclusively to these services.

BIBLIOGRAPHY

Hoffmann-Axthelm, Walter, trans. H. M. Koehler. History of Dentistry. Chicago: Quintessence, 1981.

Jedynakiewicz, Nicolas M. A Practical Guide to Technology in Dentistry. London: Wolfe, 1992.

Jong, Anthony W., ed. Community Dental Health. St. Louis, Mo.: Mosby, 1988.

Prinz, Hermann. Dental Chronology: A Record of the More Important Historic Events in the Evolution of Dentistry. Philadelphia: Lea & Febiger, 1945.

Ring, Malvin E. Dentistry: An Illustrated History. New York: Abrams, 1985.

Weinberger, Bernhard W. An Introduction to the History of Dentistry. St. Louis, Mo.: Mosby, 1948.

Wynbrandt, James. The Excruciating History of Dentistry. New York: St. Martin's Press, 1998.

CathyCurtis

dentistry is the art or science of treating diseases of the teeth and of the gums around them. As with medicine, dentistry is subdivided into a number of specialities. Oral surgery includes tooth extractions and operations on the jaw bones and the soft tissues of the mouth. Oral medicine deals with the treatment of local or systemic diseases affecting the mouth. Restorative dentistry involves replacement of parts of teeth or missing teeth. Fillings may be made from ‘plastic’ materials, such as amalgams or tooth-coloured composite resins, or pre-cast inlays; larger restorations may require metal or ceramic crowns. Restorative dentistry also includes endodontics (treating the pulps or root canals of teeth) and prosthodontics. In prosthodontics, missing teeth are replaced either with fixed bridges (using crowns placed on healthy teeth to support the ‘pontic’ that replaces the missing tooth or teeth) or removable dentures (false teeth) that may be partial or complete, depending on whether some or all of the natural teeth have been lost. Periodontics covers treatment of diseases of the gums (gingivitis) and other tissues around the teeth (periodontitis). Orthodontics is the correction of misalignment of teeth using appliances (‘braces’), which may be held by brackets glued to the teeth (fixed appliances) or retained with wire clasps (removable appliances). Paedodontics covers all aspects of dentistry in children.

The earliest references to teeth and dental diseases are inscriptions written on clay tablets around 5000 years ago in Mesopotamia. The first known dentist was Hesi-Re. He lived in Egypt around 3000 years ago, and was described as ‘the greatest of the physicians who treat teeth’. In ancient times, dental ‘treatment’ consisted mainly of tooth cleaning and perhaps some tooth extractions. Dentures (false teeth) first appeared in Sidon (Lebanon) and Tuscany around 630 bce. Here, gold bands and wires were used to attach false teeth (usually carved from ivory) to adjacent healthy teeth. The Romans were very oral hygiene-conscious. They washed their teeth and cleaned them with tooth powders (dentifrices). In ancient Greece and Rome, as in Egypt, dentistry was performed by general physicians. Practitioners were skilled in restoring carious teeth with gold and replacing missing teeth with false ones. These false teeth were ridiculed by the poet Martial, who wrote in the first century ad:
Lucania has white teeth; Thaïs brown. How comes it? One has false teeth, one her own.During the Dark and Middle Ages in Europe (approximately from 500–1500 ad), progress in medicine halted and there were no real advances for nearly 1000 years. However, during this period knowledge was sustained by Islamic scholars such as Albucasis, who wrote extensively on teeth and tooth cleaning. The importance of oral hygiene was widely recognized in the Orient. During this period Hindus and the Chinese developed various dental treatments and complex surgical procedures. In Europe, by the fifteenth century ‘dentistry’ was undertaken by barber–surgeons, physicians or apothecaries, blacksmiths, and other ‘tooth-drawers’. Herbal concoctions were the main ‘remedies’ for toothache and ‘treatment’ was confined mainly to extractions. The upper classes cleaned their teeth with cloth or sponges, and some even had gold or silver toothpicks. These were often hung round the owner's neck as an item of jewellery.

Knowledge blossomed in the Renaissance. Many of the new anatomical texts, such as Andreas Vesalius' great work De humani corporis fabrica, contained sections on teeth. Some purely dental texts were published in the sixteenth and seventeenth centuries, but the foundations of modern dental practice were laid in Pierre Fauchard's Le Chirurgien Dentiste (1728). Fauchard's book was a comprehensive discourse on a wide range of treatments. He described techniques for scraping out caries and filling the cavities with soft metals such as tin, lead, or gold. His book also gave rise to the modern term ‘dentist’ or ‘dental surgeon’.

Prior to 1844, there were no anaesthetics to abolish the pain of surgery. However, opium and laudanum (tincture of opium) were freely available ‘over the counter’. Dorothy Wordsworth (sister of the poet William) wrote: ‘I had toothache in the night. Took laudanum.’ In 1844, an American dentist, Horace Wells, was the first person to experience tooth extraction under nitrous oxide analgesia. Two years later, William Morton extracted a tooth under ether anaesthesia. In 1884, a Dr Nash was the first person to fill a tooth using cocaine injected as a local anaesthetic. In 1905, cocaine was replaced by the synthetic drug novocaine (procaine). This in turn was replaced by lignocaine (lidocaine), which is in use today.

In the eighteenth century, dentures were hand-carved from materials such as ivory, and so did not fit well. Springs were sometimes used to help improve the stability of these loose dentures. However, dentures did not improve until the invention (by Nelson Goodyear) of a hardened rubber (‘Vulcanite’) which allowed closely-fitting denture bases to be constructed on casts made from impressions of the patient's mouth. As well as fitting better, vulcanite dentures were cheaper to make.

Other developments in the nineteenth century included the reclining dental chair, amalgam fillings (which were controversial even in the 1850s), and the treadle engine for driving the dental drill. The first electric-powered dental drill was invented in 1868. Many of the technical aspects and skills of dentistry were established by the end of the nineteenth century and some have remained more or less unaltered to the present day. The principles of cavity cutting, formulated by G. V. Black in the 1880s, have been supplanted only recently with the advent of adhesive filling materials. Developments in the twentieth century included improvements in dental materials, the introduction of the ‘high-speed’ drills (powered by compressed air), and greater emphasis on instrument sterility and cross infection control.

The modern dentist is part of a team, which includes a dental nurse (dental assistant), a technician, and ancillary operators such as dental hygienists, dental therapists, and dental radiographers. Dentistry is changing from being a pain-relief and patch-up service to a profession which places emphasis on prevention of tooth decay (dental caries) and gum disease (gingivitis and periodontitis). These diseases are largely preventable with good diet and effective oral hygiene. Their effects can be minimized by early diagnosis and treatment. Fluoride can help prevent caries, by making the enamel more resistant to attack by plaque acids, but it can also cause staining or mottling of the teeth (fluorosis). Artificial fluoridation of water supplies would reduce the incidence of caries, especially amongst people with poor standards of oral hygiene. However, fluoridation of public water supplies is a controversial political issue. The recent improvements in dental health can be illustrated by data from Great Britain. In 1968, 37% of adults in England and Wales had no natural teeth. In Scotland in 1972, 44% of adults had lost all their teeth. By 1988, these figures had fallen to 20% in England and Wales and 26% in Scotland. These improvements were due mainly to the better dental health in people under 35 years of age.

In spite of these improvements in dental health, teeth are still extracted because of decay. General anaesthesia (GA) was widely used for tooth extraction in young children and in some adults with a fear of injections. In the UK, the use of GA for dental procedures has been restricted. This is intended to eliminate the small numbers of deaths each year associated with dental GA. Since 1998, GA can be administered only by suitably qualified anaesthetists in clinics where proper emergency facilities and staff are available. One alternative to GA is conscious sedation. Here, the patient is awake and can respond to verbal commands, but is ‘relaxed’. Sedation is produced using drugs such as a nitrous oxide– oxygen mixture, or tranquillizers such as diazepam (Valium), and is normally used along with appropriate local anaesthesia.

What of the future? The improvements in dental health must be sustained. A major priority is to find effective alternatives for injected local anaesthetics and replacements for the dental drill. One interesting area of development is the use of chemicals to remove caries without the need for drilling. The decay is dissolved by acids and the softened debris is scooped out. Laser technology, too, is developing and in time may replace the drill in restorative dentistry. The advent of adhesive, tooth-coloured fillings has revolutionized restorative dentistry. It is no longer necessary to cut large cavities for amalgam fillings. Instead, fillings can be placed with the minimum loss of healthy tooth substance. In prosthodontics, metal posts implanted in the jaw bones can be used to improve the support and efficiency of dentures. Nowadays, people live longer and can expect to have their natural teeth when they die. The science of dental gerontology has emerged to meet the dental needs of elderly people. Cosmetic dentistry, too, is a growth industry. Thin veneers can be used to correct defects on the outer surfaces of anterior teeth. The current trend of body adornment has extended to teeth, and small gems or gold shapes (‘Twinkles’) can be glued to the tooth surface. But cosmetic dentistry is not new. Many societies in Africa and America file the teeth for decorative and ceremonial purposes. In the ninth century the Mayans placed decorative inlays in anterior teeth. These inlays of semi-precious stones were fixed into cavities cut with a simple bow drill. Such skills were not introduced to Europe until many centuries later.

Robin Orchardson

Bibliography

Hillam, C. (1990). The roots of dentistry. British Dental Association, London.
Ring, M. E. (1993). Dentistry: an illustrated history. H. N. Abrams Inc., New York.

Dentistry

Dentistry is the medical field concerned with the treatment and care of the teeth, the gums, and the oral cavity. This includes treating teeth damaged by tooth decay, accidents, or disease. Dentistry is considered an independent medical art, with its own licensing procedure. Orthodontics is the branch of dentistry concerned with tooth problems such as gaps between the teeth, crowded teeth, and irregular bite. Periodontics, another branch, focuses on gum problems.

Historical dental practices

Dental disease has been one of the most common ailments known to humankind. Ancient men and women worked hard to alleviate dental pain. As early as 1550 b.c., Egyptians used various remedies for toothache, which included such familiar ingredients as dough, honey, onions, incense, and fennel seeds.

The Egyptians also turned to superstition for help in 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 Greek physician Hippocrates (c. 460–c. 377 b.c.), considered the father of medicine, believed that food lodged between teeth was responsible for tooth decay. He 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, myrrh, and white wine.

Clean teeth were valued by the ancient Romans. Rich 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. Earthworms marinated in vinegar were used for a mouth wash, and urine was thought of as a gum strengthener.

The Chinese were the first to develop an amalgam (mixture of metals) filling, which was mentioned in medical texts as early as 659. The Chinese also developed full dentures by the twelfth century and invented the toothbrush model for our contemporary toothbrushes in the fifteenth century.

The writings of Abu al-Qasim (936–1013), a Spanish Arab surgeon, influenced Islamic and 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. Abu al-Qasim (also known as Abulcasis) was one of the first to document the size and shape of dental tools, including drawings of dental saws, files, and extraction forceps.

Words to Know

Amalgam: Mixture of mercury and other metal elements used in making tooth cements.

Bridge: Partial denture anchored to adjacent teeth.

Denture: Set of false teeth.

Gingivitis: Gum inflammation.

Orthodontics: Branch of dentistry concerned with tooth problems such as gaps between the teeth, crowded teeth, and irregular bite.

Periodontics: Branch of dentistry focusing on gum problems.

Periodontitis: Gum disease involving damage to the periodontal ligament, which connects each tooth to the bone.

Plaque: Deposit of bacteria and their products on the surface of teeth.

The father of modern dentistry is considered to be French dentist Pierre Fauchard (1678–1761). Fauchard's work included filling teeth with lead or gold leaf tin foil. He also made various types of dentures and crowns from ivory or human teeth. In his influential writings, Fauchard explained 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 mistaken belief that worms in the mouth played a role in tooth decay.

The development of many dental tools and practices in the nineteenth century laid the groundwork for present-day dentistry. Many of the great advances were made by Americans. The world's first dental school, the Baltimore College of Dentistry, opened in 1847. Around this time, anesthesia such as ether and nitrous oxide (laughing gas) was first used by dentists on patients having their teeth pulled. The practice of dentistry was further changed by the development of a drill powered by a foot pedal in 1871 and powered by electricity in 1872.

Another major discovery of the era was the X ray by German physicist Wilhelm Conrad Röntgen (1845–1923) in 1895. The first X ray of the teeth was made in 1896. Contemporary dentists continue to use X rays extensively to determine the condition of the teeth and the roots.

Cavities and fillings

Dental cavities, or caries, are perhaps the most common type of present-day oral disease. Cavities occur when bacteria forms a dental plaque on the surface of the tooth. Plaque, which is sticky and colorless, is a deposit of bacteria and their products. 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 that must be filled or greater damage may occur, including eventual loss of the tooth.

The process of fixing dental cavities can be a short procedure depending on the size of the cavity. Small cavities may require no anesthesia and minimal drilling. Extensive dental cavities may require extensive drilling and novocaine or nitrous oxide to dull the pain. The process of

filling a cavity typically begins with the dentist using a drill or a hand tool to grind down the part of the tooth surrounding the cavity. The dentist then shapes the cavity, removes debris from the cavity, and dries it off. A cement lining is then added 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.

Tooth replacement

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

Bridges are devices that clasp new teeth in place, keep decayed teeth strong, and support the teeth in a proper arrangement. Some are removable by the dentist, and may be attached to the mouth by screws 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. A base in which to set the teeth must be designed to fit the mouth exactly. An impression of the existing teeth and jaws is taken to form this base. Modern 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

Gum disease is an immense problem among adults. Common gum diseases include gingivitis and periodontitis. 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.

Periodontitis and gingivitis are caused primarily by bacterial dental plaque. This plaque includes bacteria that produces destructive enzymes in the mouth. These enzymes can damage cells and connective tissue. Untreated periodontal disease results in exposure of tooth root surfaces and pockets between the teeth and supporting tissue. This leaves teeth and roots open to decay, ending in tooth loss. When damage from the disease is too great, periodontal surgery is performed to clean out and regenerate the damaged area.

The art of moving teeth

The position of teeth in the mouth can be shaped and changed gradually using pressure. To straighten teeth, dentists usually apply braces. Braces are made up of a network of wires and bands of stainless steel or clear plastic. The bands are often anchored on the molars at the back of the mouth and the wires are adjusted to provide steady pressure on the surface of the teeth. This pressure slowly moves the teeth to a more desirable location in the mouth and enables new bone to build up where it is needed. Braces are usually applied to patients in their early teens and are worn for a specific period of time.

DENTISTRY

DENTISTRY. Food and dental health interact, with each having effects on the other. Patterns of eating affect the health of the teeth and other tissues in the mouth, while the ability to chew a variety of foods without discomfort influences a person's nutritional state as well his or her enjoyment of eating.

Sugar and Dental Caries

The clearest link between food and dental health is between sugar consumption and caries (cavities). A study in the 1940s compared the dental health of children in an area of northern India, where food was scarce and malnutrition common, to that of better-nourished children in Lahore and in Rochester, New York. The poorly nourished children had the fewest cavities. Subsequent research confirmed that populations who enjoyed a good nutritional status had more caries than less well-nourished populations.

Researchers then looked at the mechanism of caries development to discern the role of diet. Cavities are the end result of a process that involves bacteria and sugars in the mouth over time. Streptococcus mutans, bacteria that are normally present in plaque, a very fine film which covers the surfaces of the teeth, metabolize sugar and form acid. When a person consumes sugar in foods or beverages, acid is formed that can dissolve minute amounts of minerals from the enamel surface of the tooth. When this happens repeatedly over time, enough minerals are lost for a cavity to form.

This relationship between sugar consumption and caries was tested in a classic study conducted at Vipeholm, a mental institution in Sweden, and reported in 1954. Although modern ethical standards would preclude a study in which subjects were unable to give informed consent, it remains a landmark piece of research. Residents were assigned to several groups. All ate the standard diet of the institution, but some were given additional sweets in varying quantities and frequency, up to twenty-four sticky toffee candies per day. After five years of observation, the researchers concluded that the stickiness of the sweets and the frequency with which they were consumed, both increasing the amount of time that the bacteria in plaque could produce acid, were more important than the total amount of sugar.

Streptococcus mutans can feed on any carbohydrate, not just sugars. The bacteria make no distinction between "natural" carbohydrates, such as the sugars in fruit, and refined sugars; they make acid from any of them.

Oral bacteria also make acid from sugar in liquids. This can lead to a particular pattern of caries called "baby-bottle caries," which develops when a baby is put to bed with a bottle filled with sugar-containing liquid, including milk. When the baby falls asleep, the liquid pools in the mouth, leading to decay, most often of the front upper teeth.

Since sugar has been shown to play such a significant role in the development of tooth decay, a basic preventive measure is to limit the frequency of sugar consumption. Because it is the action of bacteria on the sugar that is of concern, minimizing the bacteria by careful attention to oral hygiene is equally important. Fluoride, a mineral that is naturally present in water in some areas, has a strong protective effect as well. It binds to the other minerals to become part of the enamel, making the enamel harder and more resistant to decay. It also slows acid formation and promotes repair of places on the teeth where acid has dissolved some of the minerals.

In areas where the naturally occurring level of fluoride in water is low, it is often added during water treatment. Although there have been controversies about water fluoridation, public health authorities, including the American Dental Association, the United States Public Health Service, and the World Health Organization, all support it as a safe and effective preventive measure. One can see its effectiveness in the fact that, although sugar consumption in the United States has been increasing, children have fewer cavities than they had in the years before fluoridation became widespread.

Sugar substitutes are used to produce candies, chewing gum, and beverages that taste sweet without harming the teeth. Chewing gum containing xylitol, one of these alternative sweeteners, has been shown to be protective.

Diet and Periodontal Disease

Gingivitis, or periodontal disease, is the other common dental disorder. The bacteria in dental plaque cause an infection of the gums and structures that hold the teeth in place. The gums become red, swollen, and tender. Food does not play an important role in the development of gum disease, as it does in the formation of caries. Good oral hygiene is the most important preventive measure. A nutritious diet, which supplies generous amounts of vitamins and minerals, can offer some benefit by helping to maintain the immune system's ability to fight the infection.

Dental Status and Eating

The other side of the food and dental health interaction is the importance of healthy dentition in enabling people to eat and enjoy a wide variety of foods. The absence of a significant number of teeth or a condition such as periodontal disease or poorly fitting dentures, which makes chewing uncomfortable, may limit a person's food choices and compromise his or her nutritional status. This problem occurs most frequently in elderly and low-income populations, who are more likely to be at risk for nutritional problems.

Some researchers do not find this effect, possibly because the subjects with poor dentition have chosen nutritious foods that are easy to chew, or because the comparison population ate no better in spite of good dental status. In general, however, poor dental health increases the risk of poor nutritional health. Good dental care can correct most of these problems and enable individuals to enjoy eating a nutritious diet.

See also Digestion ; Fluoride .

BIBLIOGRAPHY

American Dental Association web site. Available at www.ada.org.

Burt, B. A., and S. Pai. "Sugar Consumption and Caries Risk: A Systematic Review." Paper presented at the Consensus Development Conference on Diagnosis and Management of Dental Caries throughout Life, Bethesda, Md., March 2001.

FDI Working Group. "Nutrition, Diet, and Oral Health: Report of and FDI Working Group." International Dental Journal 44 (1994): 599–612.

Gustaffson, B. E., C. E. Quensel, L. S. Lanke, et al. "The Vipeholm Dental Caries Study: The Effect of Different Levels of Carbohydrate Intake on Caries Activity in 436 Individuals Observed for Five Years." Acta Odontologica Scandinavica 11 (1954): 232–364.

Mona R. Sutnick

dentistry treatment and care of the teeth and associated oral structures. Dentistry is mainly concerned with tooth decay, disease of the supporting structures, such as the gums, and faulty positioning of the teeth. Like medicine and surgery, it is practiced in specialized fields: oral surgery, orthodontics (corrective dentistry), periodontics (diseases of the gums), prosthodontics (partial or total tooth replacement), endodontics (treatment of dental pulp chamber and canals), and pedodontics (dental problems of children).

Some researchers believe that there is clear evidence of dental drilling in human teeth found in Pakistan that date to 7000 BC, but unquestioned evidence of dentistry is found only from subsequent millenia. Excellent crowns and bridges were made by the Etruscans in the 7th cent. BC At about that time, teeth were being extracted in Asia Minor as a cure for bodily ills and diseases. Skills achieved by the Etruscans, Phoenicians, Egyptians, Greeks, and Romans were largely lost during the Middle Ages , when barbers and roving bands of charlatans practiced unskilled dentistry at marketplaces and fairs. Abulcasis , a Spanish Moor, was one of the few in his time who studied dental surgery, leaving behind instruments and theories quite advanced for the 10th cent. AD

French scientist Pierre Fauchard is considered the founder of modern dentistry; by the end of the 17th cent., he was making fillings of lead, tin, and gold and devising artificial dentures. In the 18th cent., German scientist Philip Pfaff was making dentures of plaster of Paris, and shortly thereafter the French discovered how to mold porcelain into dentures. The first American to make use of this process was Charles Willson Peale ; he who made the now-famous set of false teeth for George Washington .

As dentistry progressed, the center of accomplishment shifted from Europe to the United States. The first dental school in the world was established in Baltimore in 1840. The development of local and general anesthesia, the invention of the drilling machine, discovery of better substances for filling teeth (amalgam and gold), and, most importantly, the ability to devise replacements closely approximating natural teeth in function and appearance contributed much to the rapid growth of dentistry as a science and an art. Adding fluoride to the local water supply ( fluoridation ) has made teeth more resistant to cavities; annual applications of fluoride and clear liquid plastic to children's teeth also make them more decay resistant.

New developments include the implantation of artificial teeth or binding posts into the gums or jawbone; antibiotic fiber for periodontal disease; root canal surgery, a procedure that ameliorates pain while permitting teeth to remain in place; and nearly painless lasers to repair dental cavities, usually making local anesthesia unnecessary. In the early 1990s, it was reported that five patients of a Florida dentist with AIDS became infected with HIV ; as a result, the Occupational Safety and Health Administration (OSHA) ruled that full protective garb (gloves, mask, glasses or goggles, coat) be worn by dental personnel to protect patients and themselves.

dentistry Profession concerned with the care and treatment of the mouth, particularly the teeth and their supporting tissues, the gums and oral bones. As well as general practice, dentistry includes specialities such as oral surgery, periodontics (structures around the teeth) and orthodontics (irregular teeth and jaws).

dentistry (den-tist-ri) n. the profession concerned with care and treatment of diseases of the teeth, gums, and jaws.

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