Tooth decay  

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Tooth decay, also known as dental caries or cavities, is a breakdown of teeth due to acids made by bacteria. The cavities may be a number of different colors from yellow to black. Symptoms may include pain and difficulty with eating. Complications may include inflammation of the tissue around the tooth, tooth loss, and infection or abscess formation.

History

There is a long history of dental caries. Over a million years ago, hominins such as Australopithecus suffered from cavities. The largest increases in the prevalence of caries have been associated with dietary changes. Archaeological evidence shows that tooth decay is an ancient disease dating far into prehistory. Skulls dating from a million years ago through the neolithic period show signs of caries, including those from the Paleolithic and Mesolithic ages. The increase of caries during the neolithic period may be attributed to the increased consumption of plant foods containing carbohydrates. The beginning of rice cultivation in South Asia is also believed to have caused an increase in caries, although there is also some evidence from sites in Thailand, such as Khok Phanom Di, that shows a decrease in overall percentage of dental caries with the increase in dependence on rice agriculture.

A Sumerian text from 5000 BC describes a "tooth worm" as the cause of caries. Evidence of this belief has also been found in India, Egypt, Japan, and China. Unearthed ancient skulls show evidence of primitive dental work. In Pakistan, teeth dating from around 5500 BC to 7000 BC show nearly perfect holes from primitive dental drills. The Ebers Papyrus, an Egyptian text from 1550 BC, mentions diseases of teeth. During the Sargonid dynasty of Assyria during 668 to 626 BC, writings from the king's physician specify the need to extract a tooth due to spreading inflammation. In the Roman Empire, wider consumption of cooked foods led to a small increase in caries prevalence. The Greco-Roman civilization, in addition to the Egyptian, had treatments for pain resulting from caries.

The rate of caries remained low through the Bronze Age and Iron Age, but sharply increased during the Middle Ages. Periodic increases in caries prevalence had been small in comparison to the 1000 AD increase, when sugar cane became more accessible to the Western world. Treatment consisted mainly of herbal remedies and charms, but sometimes also included bloodletting. The barber surgeons of the time provided services that included tooth extractions. Learning their training from apprenticeships, these health providers were quite successful in ending tooth pain and likely prevented systemic spread of infections in many cases. Among Roman Catholics, prayers to Saint Apollonia, the patroness of dentistry, were meant to heal pain derived from tooth infection.

There is also evidence of caries increase in North American Indians after contact with colonizing Europeans. Before colonization, North American Indians subsisted on hunter-gatherer diets, but afterward there was a greater reliance on maize agriculture, which made these groups more susceptible to caries.

During the European Age of Enlightenment, the belief that a "tooth worm" caused caries was also no longer accepted in the European medical community. Pierre Fauchard, known as the father of modern dentistry, was one of the first to reject the idea that worms caused tooth decay and noted that sugar was detrimental to the teeth and gingiva. In 1850, another sharp increase in the prevalence of caries occurred and is believed to be a result of widespread diet changes. Prior to this time, cervical caries was the most frequent type of caries, but increased availability of sugar cane, refined flour, bread, and sweetened tea corresponded with a greater number of pit and fissure caries.

In the 1890s, W.D. Miller conducted a series of studies that led him to propose an explanation for dental caries that was influential for current theories. He found that bacteria inhabited the mouth and that they produced acids that dissolved tooth structures when in the presence of fermentable carbohydrates. This explanation is known as the chemoparasitic caries theory. Miller's contribution, along with the research on plaque by G.V. Black and J.L. Williams, served as the foundation for the current explanation of the etiology of caries. Several of the specific strains of lactobacilli were identified in 1921 by Fernando E. Rodriguez Vargas.

In 1924 in London, Killian Clarke described a spherical bacterium in chains isolated from carious lesions which he called Streptococcus mutans. Although Clarke proposed that this organism was the cause of caries, the discovery was not followed up. Later, in the 1950s in the USA, Keyes and Fitzgerald working with hamsters showed that caries was transmissible and caused by an acid-producing Streptococcus. It was not until the late 1960s that it became generally accepted that the Streptococcus isolated from hamster caries was the same as S. mutans described by Clarke.

Tooth decay has been present throughout human history, from early hominids millions of years ago, to modern humans. The prevalence of caries increased dramatically in the 19th century, as the Industrial Revolution made certain items, such as refined sugar and flour, readily available. The diet of the “newly industrialized English working class” then became centered on bread, jam, and sweetened tea, greatly increasing both sugar consumption and caries.