Advances in Dentistry, 1900-1949

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Advances in Dentistry, 1900-1949

Overview

During the years 1900 to 1949 major advances occurred in dental development. Improvements in dental drills and filling techniques, the advent of fluoride treatment, the development of orthodontics, and new ideas about the connection between teeth and the overall health of the body enabled the profession to advance as a major segment of the health care industry. These developments would set the stage for additional advances during the later half of the century.

Nearly all major dental specialties had their inception in the first half of the twentieth century: orthodontics, the science of straightening teeth, 1901; oral surgery, 1918; periodontics, treating gums and gum disease, 1918; prosthodontics, making dentures and bridges, 1918; pedodontics, children's dentistry, 1927; public health, 1937; and oral pathology, 1946. Only endodontics (1963) did not begin during this time.

Background

From the beginning of recorded history, dental problems have plagued human beings. Ancient chronicles tell of toothaches, dental decay, periodontal disease, and tooth loss. Magic, myth, and religious experiences all played a part with some odd beliefs emerging. For example, the ancient Egyptians believed that the sun god protected mice, so for a toothache the body of a warm mouse was split and applied to the jaw to bring relief. Early Christians prayed to Saint Apollonia of Alexandria (a.d. 249) for pain relief, and she became the Patron Saint of Dentistry.

During the dark days of the Middle Ages, monks, along with barbers, became physicians and dentists. However, when a pope ruled in 1163 that this was not suitable for monks, the barbers took over completely. The barber-surgeon did extractions along with itinerant groups called tooth drawers, who operated in the public square. Many of these were spectacular showmen, such as "le grand Thomas" who appeared in Paris during the time of Louis XV (1710-1774). These practitioners developed a number of tools, although they knew very little about anatomy. It was the famous anatomist Andreas Vesalius (1514-1564) who described teeth and the chambers.

French surgeon Pierre Fauchard (1678-1761), recognized as the father of scientific dentistry, realized the condition of the teeth related to health in general. He was not just interested in extraction, but devised techniques that included drilling, filling, filing, transplanting, dentures, cosmetic tooth straightening, and surgery of the jaws and gums. He set an agenda for decades of development.

While many developments affected dentistry, the major advance was the discovery of anesthesia. Two dentists—Horace Wells (1815-1848) and William Morton (1819-1869)—are credited with introducing this development during the mid-nineteenth century. In the 1890s W. D. Miller found that teeth could be made to decay in a test tube by exposing them to bacteria and carbohydrates. Although x-rays were discovered and used by Edward Kells in dentistry in 1895, it was not until the next century that this technique was accepted and used.

Impact

The new century began with many new discoveries that would expand and lead to great improvements in dentistry.

The dental drill has been one of the most feared and hated devices, but its history reveals that ingenious investigators recognized the benefits of removing dental caries. George Washington's dentist, John Greenwood (1760-1819), used his mother's foot treadle on the spinning wheel to develop a rotating drill. In 1868 American George F. Green introduced a pneumatic drill powered by a pedal billows. Electricity was added to drills in 1874, but the devices were heavy and expensive. By 1908 almost all dental offices had electricity, though, compared to today's high speed drills, they were slow and cumbersome. However, the drills did make it possible to fill teeth and fit crowns. The use of diamond bits and carbide burrs were introduced in about 1925. The air abrasive drill was introduced in 1945. Now, modern drills are turbine-powered and rotate at speeds of 300,000 to 400,000 revolutions per minute.

Many materials have been used to fill teeth: stone chips, turpentine, resin, metals of all kinds, and gold. The improvement of drills opened up a whole new era of filling teeth. A race was on to find the best material. Several different types of amalgam (mixtures of various metals) were used, with many of them containing mercury. After a series of "amalgam wars," Chicago dentist G. V. Black (1836-1915) was able to establish a standard in 1895. In 1907 William H. Taggart successfully demonstrated the casting of gold inlays, which made possible accurate filling and inlay fitting.

Likewise, dental education was becoming more sophisticated. The first dental school had been established in the United Kingdom by the Odontological Society of London. In the United States, the first dental school associated with a university opened at Harvard in 1867. In 1899 one year of high school was established as a prerequisite for admission to dental school. Just a few years later, in 1903, a four year's course in a dental college was developed. In 1921 the requirement was changed to one year of college. The first official bulletin was published in 1913. The National Dental Association changed its name to the American Dental Association in 1922.

Dentures became an answer to the extraction of teeth. Developing satisfactory materials for dentures has a history that involves not only medical, but also legal and ethical, questions. In 1851 Nelson Goodyear, brother of Charles Goodyear (1800-1860), who first developed vulcanized rubber, found a way to make dentures from rubber that worked well and had a fairly low cost. The only problem was that the base had a dark red color and did not look desirable. These dentures were a great advance, and in 1864 Goodyear got a patent, licensed the dentists who used them, and changed a royalty for each set. Many dentists despised these patents, but always lost the legal battles. In 1879 a very respected dentist, Samuel Chalfant, shot Josiah Baron, the attorney hired by Goodyear to prosecute noncompliance. When the patents expired in 1881, Goodyear did not seek to renew the licensing of dentists. These vulcanite dentures were used until 1940, when pink acrylic dentures replaced them.

At the beginning of the twentieth century anesthesia had been introduced. The gas nitrous oxide was identified by Joseph Priestley (1733-1804) in 1772, and Humphrey Davy (1778-1829) noted that when this was breathed, people became hilarious and silly. The popular term "laughing gas" was given, but Davy's observation that it seemed to make people oblivious to pain was ignored. Horace Wells is credited with first recognizing the value of applying practical anesthesia to dentistry. Wells attended a demonstration by a traveling chemist, Gardner Q. Colton, who had people inhale the gas for the amusement of the audience. Wells noticed how the volunteers scraped their shins on the heavy benches and felt no pain. He was the first to devise the idea of inhaling anesthesia.

Cocaine was introduced as the first local anesthesia in 1884 when William S. Halstead (1852-1922) demonstrated that its injection into an area could block pain. In 1905 Professor Braun introduced novocaine (procaine hydrochloride) for dentistry. Novocaine's low toxicity and general absorption into body tissue made it a quick and relatively safe anesthesia. Novocaine is detoxified in the liver and rapidly hydrolyzed in the plasma. The drug then infiltrates around nerve endings and fibers, and its painkilling effect is almost immediate. Now, novocaine is seldom used, for it has been replaced by primacaine or tetracaine. During World War I, Harvey Cook noted the use of cartridges in rifles and conceived the idea of putting anesthesia solution in cartridges. From this observation came the development of syringes for the delivery of drugs. In 1943 Swedish chemists Nils Lofgven and Bengst Lundquist introduced lidocaine (xylocaine hydrochloride) and tested it extensively. By 1950 it was widely accepted. Xylocaine goes quickly into the nerve sheath and rapidly deadens feeling with very few side effects.

In 1895 Karl Wilhelm Roentgen (1845-1923), a German professor of physics, was studying a cathode ray that glowed inside a spiral tube when high voltage was applied. He darkened his lab and wrapped the tube in black cardboard. He noted strange rays that produced an outline of bones in his hands through the skin. He called the beams x-rays because they were unknown. He was awarded the 1901 Nobel Prize for Physics and an honorary doctor of medicine. X-rays were accepted at once. Roentgen refused to patent x-rays because he thought it was a gift for the benefit of mankind. Dr. Edmund Kells of New Orleans, Louisiana, and Otto Walkhoff of Munich, Germany, first applied x-rays to locate impacted teeth. Soon the method of looking beneath the surface extended to locating decay and other problems in teeth.

Several nineteenth-century dentists contributed to the development of orthodontics, or straightening teeth. Norman W. Kinglet and J. N. Farrar wrote treatises on the new dental science. Edward H. Angle (1855-1930) built upon previous work to design a system of classification of malocclusion. He also designed orthodontic appliances and simplified other ones. He founded the first school or orthodontics and was an original member of the American Society of Orthodontics in 1901. He was a prolific writer and founded an orthodontic journal as well as producing a major text, The Malocclusion of Teeth. Some of his classifications are still used today.

In 1948 Congress created the National Institute of Dental Research as part of the National Institutes of Health, Bethesda, Maryland. The institute sup000ports about 100 research and educational centers in the United States.

EVELYN B. KELLY