Mastic Toothpaste for Healthier Gums and Teeth
Mastic Toothpaste for the New Millennium
By Will Block
Contrary to popular folklore about the good old days, the mouths of our ancestors were just as alive with unhealthy, squirming bacteria as ours are today. Even before the origin of the human species, oral disease may have been a problem. An examination of the skull of an Australopithecus africanus specimen - a human predecessor that inhabited the earth between 2.5 and 2 million years ago - found evidence of tooth loss due to periodontal disease.1 In a Neolithic settlement on the island of Cyprus in the Mediterranean Sea (5,800-3,000 B.C.), 38 skulls of various age groups were examined and evaluated in areas where teeth still existed.2 The alveolar (tooth-socket) bone mass was found to decrease with age, indicating that periodontal disease has accompanied human beings since prehistoric time. In Britain during the past 3,000 years, the prevalence of periodontitis - a gum disease caused by certain bacteria - was found to have remained virtually constant, despite considerable changes in the hygienic environment.3
From these studies, and others, researchers have concluded that the major cause of tooth loss is the formation of plaque. Indeed, in the Neolithic skulls, the effects of periodontal disease were related to the amount of plaque on the remaining teeth. Yet, as we shall learn, the history of dentistry is largely one of dealing with decayed teeth: filling them, yanking them out, and replacing them. It has taken thousands of years of dentistry to learn how to prevent caries (tooth decay) and periodontal disease and how to start reversing damage that has already occurred.
Early Inquiries on Dental Problems
Scientific dentistry arose slowly, and not without many false starts. For example, the earliest references to oral disease in ancient (5,000 B.C.) Sumerian texts describe "tooth worms" as a cause of dental decay.3 Not knowing the cause of decay, the Chinese were performing dental extractions as early as 4,000 B.C.,4 and around 2,700 B.C. they used acupuncture to treat toothache.5 During the same time in Egypt, despite the seriousness given to dentistry, periodontal disease was undeterred: mummies have been found to have suffered tooth loss due to tooth decay.6
Among the most famous medical documents of antiquity is the Ebers Papyrus, written in ancient Egypt between 1,700 and 1,500 B.C. and referencing material dating back as far as 3,700 B.C.7 Certain parts of it concern diseases of the teeth, as well as plasters or prescriptions for substances such as olive oil, dates, onions, beans, and green lead, to be mixed and applied "against the throbbing of the bennut [seedlike] blisters in the teeth."8 It was during this earlier time that the Egyptians developed dental surgery (about 2,800 B.C.), and dentistry broke away from general medicine. The Greek historian Herodotus wrote in the fifth century B.C. that, "in Egypt, medicine is practiced on a plan of separation - each physician treats a single disorder, and no more . . . some undertaking to cure diseases of the eye, others of the head, others again of the teeth." (There is no record, however, of their having HMOs too.)
Etruscans and Surgical Dentistry
In the eighth and ninth centuries B.C., the Etruscans evolved into an urban population of craftsmen who dominated the Mediterranean region around Italy.9 Their extraction techniques and elaborate dentures exceeded the know-how of the Egyptian and Phoenician cultures and were not matched until the nineteenth century. The dental space retainers in use today are still very much like the ones invented by the Etruscans. Despite all their technical work, however, Etruscans did not contribute much to the prevention or cure of oral disease. Skills of prevention made no inroads: periodontal disease and caries were untreatable.
The Romans, who inherited the ideas of the Etruscans, did not add much technically, and by the fall of the Roman Empire in A.D. 476, all advances made in Etruscan dentistry had been lost.
The Greeks had learned as early as 1,300 to 1,200 B.C. to extract diseased teeth, and Hippocrates and Aristotle (500-300 B.C.) used cautery with a red-hot wire to treat disease as they created ointments to sooth oral tissues.10 They wrote about the use of wires to stabilize jaw fractures or bind loose teeth. They could remedy the loss of teeth but could not stop the diseases that caused oral misery.
A giant among Roman physicians, Celsus (born about 10 B.C.), wrote extensively of oral diseases, including bleeding gums and ulcers of the mouth.11 His dental treatments involved narcotic-containing emollients and astringents. He saw the importance of cleaning teeth, positioning it as part of some religious ceremonies. Roman patriarchy detailed certain slaves - who might be thought of as forerunners of modern dental hygienists - to clean their teeth. The toothpaste and mouthwash that they used contained a secret ingredient: human urine! Because of its "strength," imported Portuguese urine was especially prized, but it is hypothesized that evaporation on the long trip to Rome could have been as responsible as any ethnic characteristics. Nevertheless, urine continued to be an active ingredient in toothpastes and mouthwashes until well into the eighteenth century, because the ammoniacal compounds that it contained acted as great cleansers. In fact, such compounds continue to be ingredients in many modern toothpastes, but these are now manufactured in the laboratory rather than the lavatory.
Arabic culture flourished while Europe was in the Dark Ages. The Arabs reaped the fruits of contact with the de-evolving civilizations and were adept at organizing this new knowledge.12 They established a cultured and wealthy empire with centers of learning in places as far removed as Baghdad, Cairo, and Cordova in Spain. Medical science might otherwise have died. But more than merely keeping it alive, Arabic scholars added greatly to medical science, becoming skilled in the use of anesthetics and developing the most difficult surgical procedures.
Dentistry also benefited. From the seventh to the eleventh centuries, Arabic authors translated ancient Greek and Roman medical textbooks into their own languages.13 In the eleventh and twelfth centuries, noted authors used these early translations when writing other classical texts. An Arab born near Cordova in the eleventh century, Abul-Qasim Al-Zahrawi, known in Western literature as Abulcasis (936-1013) described extraction, scaling, reduction of fractures, and the treatment of dislocated jaws in a famous treatise entitled al-Tasrif.14 (See Figure 1.) He designed fourteen different kinds of scrapers and suggested the binding together of sound teeth and filling the existing gaps with a bone substitute. Abulcasis was one of the earliest to devise a method to correct deformities in the mouth and dental arches.
Figure 1. Abul-Qasim Al-Zahrawi, author of the famous medical treatise, al-Tasrif, and the designer of dental tools.
The Toothbrush is Invented
Even more than the Romans, Arabic physicians believed that it was of great importance to maintain clean teeth, and they devised various procedures and tools to scrape them. The invention of the "toothbrush" may well be attributed to Arabs. Unlike what we have come to know, however, these consisted of small polishing sticks that were beaten and softened at one end. The world of Arabic dentistry also gave us the toothpaste powder formulations that were applied by "toothbrush" as well as in mouthwashes.
Europe in the Middle Ages
Throughout the Middle Ages in Europe, dentistry was made available to wealthier individuals by physicians or surgeons who would make house calls.15 Sometimes they removed decay from teeth with a metal rod that was rotated between the palms. Soft filling materials helped relieve some of the pain by keeping air from the open cavity. For those less opulent, self-taught vagabonds would extract teeth for a small fee in the marketplace. From the Middle Ages to the early 1700s, much dental therapy was provided by so called "barber surgeons." Operating as jacks-of-all-trades, they would also perform minor surgery, cut hair, apply leeches to let blood, and embalm the recently departed.
Banded into guilds in the fourteenth century, barber surgeons also attempted to whiten the teeth of their patients. They would first file the surface of the teeth and then soak them with aqua fortis, a solution of highly corrosive nitric acid. This produced white teeth for a while, but it also thoroughly destroyed the enamel, causing massive dental decay in midlife.
Before the relatively recent, widespread use of porcelain dentures and vulcanized rubber "gums" that served as the base of the dentures, dentists used human teeth to replace missing ones. The mouths of the poor and the dead were the two primary sources, and, like blood donors today, the poor could sell their teeth for ready cash back in the 1600s and 1700s. Grave robbers worked both sides of the street, selling not only corpses to anatomy schools, but teeth to dentists.
In Italy during the 1400s, gold leaf came into use as dental filling material. Lead fillings were later used by the French to repair teeth after decay was removed. Pierre Fauchard (1678-1761), a French surgeon, is credited with being the "father of modern dentistry." His book, The Surgeon Dentist, A Treatise on Teeth, describes the basic oral anatomy and function, signs and symptoms of oral pathology, operative methods for removing decay and restoring teeth, periodontal disease (pyorrhea), orthodontics, replacement of missing teeth, and tooth transplantation.
After Fauchard, other writing continued to expand the knowledge of the profession throughout Europe. Two popular books, Natural History of Human Teeth (1771) and Practical Treatise on the Diseases of the Teeth (1778), were written by the English physiologist John Hunter, surgeon general to the British army.
It is not coincidental that Anton van Leeuwenhoek, the great microscopist of the seventeenth century, developed a friendship with the great Dutch artist Jan Vermeer, the master of light.16 Leeuwenhoek gave us the first microscopic description of oral bacteria.
Barrels of Teeth
In the American colonies in the 1700s, dental practitioners migrated from place to place, set up shop, and devoted themselves to extraction and especially artificial dentures. Paul Revere was by trade a silversmith who constructed dentures from ivory and gold. George Washington had dentures made of metal and carved ivory, or metal and carved cow teeth, but none made of wood. He probably had some human teeth as well.
A whole generation of Europeans wore "Waterloo" dentures made from teeth yanked from the corpses - and often from wounded soldiers not yet dead - on the battlefield. George Washington's erstwhile dentist, John Greenwood, returned from a trip to Europe in 1805 with a keg of human teeth from earlier Napoleonic adventures. The practice continued as late as the Civil War, when thousands of Americans wore "Civil War" dentures. Teeth were stolen from bodies at places like Bull Run and Gettysburg. Barrel-loads of teeth of American soldiers were secretly shipped to Europe. Wearing someone else's teeth was not a bowl of cherries, however - it was an extreme hardship, but better than the alternative.
Until the mid-1800s, dentures continued to be individually constructed by skilled artisans, but they were only for the very well-to-do. Then in 1839, Charles Goodyear discovered how to vulcanize rubber, and the ability to mold this new material against a model of the patient's mouth and attach artificial porcelain teeth allowed the manufacture of less expensive dentures. Eventually, the rubber and porcelain in denture construction were superseded by acrylic plastics.
A Landmark and a Theory
A landmark of dental history was the use of nitrous oxide (laughing gas) in 1844 by Dr. Horace Wells, a Connecticut dentist. He initiated the use of nitrous oxide inhalation during dental therapy and promoted the concept of inhalation analgesia and anesthesia, which had been pioneered by surgeons. Later modified and adopted by the medical community, inhalation anesthesia using ether or chloroform became the standard surgical management procedure. It also eased the pain of decay, extraction, and bridgework, but it did not solve the problems of oral disease.
Greene Vardiman Black (1831-1915) devised a foot engine that allowed the dentist to keep both hands free while powering the dental drill. He also developed techniques for filling teeth based upon biological principles and microscopic evaluation. More remarkably, upon noting a densely matted bacterial coating on the teeth (now known as plaque), Black proposed the theory that dental caries and periodontal diseases were infections initiated by bacteria. Surprisingly, it was not until the early 1960s that scientific evidence confirmed his theory.
Oral Hygiene Devices
In the evolution of oral hygiene practices, the toothpick is the progenitor device, with a long history as civilization's primary tooth-cleaning instrument.17 Toothpicks date back at least to 3,500 B.C. in Mesopotamia, where the earliest known oral hygiene kit featuring a toothpick was found at the Ningal Temple in Ur.18 In China, a curved pendant made of cast bronze was worn around the neck and used as a toothpick.19 In 536 B.C., the Chinese passed a law requiring the use of toothpicks because their armies suffered from bad breath. Even The Old Testament chimes in, "One may take a splinter from the wood lying near him to clean his teeth."
Toothpicks probably had their heyday in the Middle Ages, when keeping one in the mouth all day long was a common habit. In the seventeenth century, toothpicks were commonly used by the educated classes throughout Europe. In France, for example, they were served with desserts, usually poked into fruit so as to be handy following the meal. They could then be placed behind the ear for future use.
Yet the West began to abandon toothpicks in the 1700s, as the recreated toothbrush gradually became the standard of care for cleaning teeth. A consensus had formed that keeping teeth clean might be able to reduce oral disease. The current emphasis is on plaque control rather than gingival massage and stimulation, and the toothpick has been largely superseded by floss, toothbrushes, and other supplementary aids. The natural hard-bristle toothbrush and vigorous scrub-brushing, popular a generation ago, have been replaced by soft-bristle nylon brushes and gentler, more defined brushing procedures for plaque removal in the crevices between teeth. Quantitative studies support the superiority of the current techniques in maintaining periodontal health with less trauma to oral tissues.
Toothpaste Came Before the Toothbrush
Going back again into the past, it is an unlikely conclusion that the paste preceded the brush, but apparently this is so. Our earliest knowledge of toothpaste is from Egypt about 5,000 years ago, when a kind of toothpaste was made using a recipe of powdered ashes of oxen hooves, myrrh (which may have been mastic), powdered and burned egg shells, and pumice. There were no specific instructions as to how this powder was to be used, but it is assumed that the ancient Egyptians used their fingers to rub it onto their teeth. The Arabic toothstick, the forerunner of the toothbrush, had not yet, as far as is known, been invented.
More recently, in China (about 500-300 B.C.), when gold and silver needles were stuck into different parts of the jaw and gum, acupuncturists were able to alleviate different types of pain in the mouth.5 Yet Chinese medicine was more pragmatic than is often believed, and out of the search to reduce pain by whatever means, dental cream was developed.
The Greeks and Romans improved toothpaste with the creation of special salves.20 With the fall of the Roman Empire, the evolution and development of toothpaste became less clear, and little is known of any changes for the next five centuries.
Toothpaste in the Last Millennium
About A.D. 1,000, evidence shows that the Persians further developed toothpaste.21 Advice was given on the dangers of using hard toothpowders, yet it was recommended to make toothpowder from burnt hartshorn, the burnt shells of snails and oysters, and burnt gypsum. Other Persian recipes included dried animal parts, herbs, honey, and minerals. One formula for strengthening teeth included green lead, verdigris, incense, honey, and powdered flintstone. Rhazes, a ninth-century Muslim physician from Persia, was the first to write about filling cavities with a "cement," which he concocted from alum and mastic, a yellowish resin from an evergreen tree, Pistacia lentiscus, in the cashew family. Mastic, one of the jewels of periodontal protection and prevention, was shortly thereafter lost to dentistry (but not to other medical uses), only to be discovered again about 1,000 years later.
By the late eighteenth century, toothpowder became available in Britain. Appearing at first in ceramic pots as a powder or paste, it was applied with brushes by the rich; the less affluent used their fingers. Developed by doctors, dentists, and chemists, toothpowders often contained ingredients that were highly abrasive and harmful to the teeth, such as brick dust, china, earthenware, or cuttlefish shells. To make them more palatable, they contained glycerine. The early nineteenth century saw the introduction of the element strontium, intended to strengthen teeth and reduce sensitivity, but it only really concentrated on the gums.
In the late eighteenth century, borax powder was used to produce a foaming effect. Aromatic toothpaste in a jar was introduced in the United States in the latter part of the nineteenth century, followed several years later by collapsible tubes similar to those in use today.
Soap was used as a toothpaste emulsifying agent until the Second World War, but it tasted bad and was incompatible with the calcium salts that comprise an important part of saliva. Following the war, advances in synthetic detergents allowed emulsifying agents such as sodium lauryl sulfate and sodium ricinoleate to be used in toothpaste. The discovery that fluoride compounds added to toothpaste strengthened the enamel against tooth decay was a major step forward.
The Rediscovery of Plaque
The surfaces of our teeth are constantly coated with organic substances that build up in layers if not removed. These substances, commonly known as dental plaque, are what Black had discovered in the early part of the twentieth century. He believed that plaque was a primary cause of periodontal disease. When allowed to remain without toothbrushing with truly effective ingredients, plaque eventually calcifies, forming another substance known as tartar. (See Figure 2.) Plaque and tartar play a crucial role in the creation of oral pathologies, including dental caries, gingivitis, and periodontal disease.
Figure 2. When plaque is not removed, it eventually calcifies, forming tartar.
As far as we know, there are over 300 species of bacteria-forming populations in the human mouth.22 When the mouth is not sufficiently cleaned, the number of bacteria can reach a thousand billion, or one trillion. What do they feed on? Their main nutrients are saliva and gingival fluid found in the crevices of our teeth. When well fed, these bacteria create ecological niches throughout our mouths: on the surfaces of our teeth and between them, in the gingival crevices. They also make themselves at home in our saliva, our tongue, the inside of our cheeks, and the mucous lining at the back of our mouth. There they threaten oral and systemic health, increasing the likelihood of primary mouth lesions and chronic bacterial infections, which may lead to kidney inflammation (nephritis), rheumatoid arthritis, and skin rashes (dermatitis).
There's more: recently oral bacteria have been demonstrated to cause bacterial pneumonia and inflammation of the heart's lining (endocarditis), and the periodontal-disease-associated bacteria cause pregnancy troubles and are involved in blood-circulation problems and coronary heart disease. Indeed, the goal of dental health care now is more far-reaching than just a clean mouth and good-looking teeth . . . it is also a healthy life.
Mastic for Toothpaste
During the height of the Roman Empire, aristocratic women used toothpicks made from mastic gum trees, because it whitened their teeth.23 Yet despite a great deal of folklore about the antibacterial powers of mastic resin, including references in scores, if not hundreds, of medical publications over the last 2,500 years, it wasn't until a study was conducted in 1984 at the University of Thessaloniki in Greece that it started to be taken seriously.
When mastic was chewed for only five days, the amount of plaque scraped from the subjects' teeth lessened by 30% compared to those who chewed a placebo.24 The authors reasoned that mastic was able to readily prevent or reduce plaque buildup because it had a favorable effect on a type of white blood cells (polymorphonuclear leukocytes) that exist in the liquid found in the gingival crevices (between the teeth and gums). These cells constitute the first line of the gums' defense against clinical inflammation.
In preliminary experiments, mastic was found to have a strong chemical affinity for white blood cells, so chewing it caused a buildup of these cells at the gums. Mastic's antibacterial action was indirectly causing the protective blood cells to interact with plaque, especially at the edge of the teeth close to the gums and in the gingival crevices.
In the study, 12 students with low levels of tooth and gum decay suspended all mouth care for ten days. During the first five days, they simply abstained from brushing their teeth. During the next five days, half of them systematically chewed mastic (1 gram three times per day), while the other half chewed paraffin wax. Both groups abstained from brushing. Then the bacterial plaque from the back teeth of each subject was collected, weighed, and analyzed for infiltration of white blood cells, and pictures were taken. The results clearly showed that with systematic use of mastic, the amount of bacterial plaque was significantly reduced, by 41.5% in comparison with the levels five days earlier. The authors concluded that it would be ideal to combine mastic in toothpaste (chewing can be a problem for those with fillings) as a helpful preventive and therapeutic measure for dental hygiene.
The French biochemist René-Maurice Gatefosse mentioned in his work that mastic has been used directly on tooth decay with positive results by dentists.23 He believed that there is strong evidence showing that mastic serves as an oral antiseptic and that it preserves and strengthens gums and teeth. He also declared that mastic could be used in dentistry as a material for fillings, and that all toothpastes should contain mastic oil as their main active ingredient.
Moreover, given the antibacterial characteristics of mastic, along with its white-blood-cell-attracting abilities, it should work even better in a toothpaste that combines other state-of-the-art anticaries and antibacterial ingredients.
Anticaries, Antibacterial Additions
Dental caries is a disease that progresses when bacteria produce an acid (as a byproduct of carbohydrate fermentation) that diffuses into the teeth and dissolves their mineral components, causing demineralization.25 Together with periodontal disease, dental caries comprises the bulk of major oral disease. Pathological factors such as disease-causing bacteria, salivary dysfunction, and dietary carbohydrates are related to caries progression. But unlike the ability of periodontal bacteria to be sufficient for disease, caries bacteria require an accomplice: carbohydrates. In ancient times, caries depended to a significant degree on the diet, but until the rise of processed carbohydrates, these compounds did not represent a significant contributor to loss of teeth - unlike periodontitis.26 Fermentable carbohydrates, including sugars, are generally accepted to be the fundamental cause of caries.
But caries is preventable. In 1802, Italian dentists noticed that patients who came from areas rich in fluoride had far less caries. Word spread, and dentists in Europe recommended to their patients that they suck on lozenges containing fluoride and mixed with honey. Today, much of our water supply is fluoridated, although the value is probably insignificant, given the widespread use of fluoride in toothpaste. Indeed, reviews of the literature indicate that ingested fluoride (as in the water supply) does not have the same effectiveness as topical fluoride (as in toothpaste).27
Fluoride acts on both the local and systemic levels. Locally fluoride prevents the surface demineralization of enamel by inhibiting bacterial activity and strengthening the superficial layers. Systemically it improves the resistance of the enamel by forming a strong calcium-bonded coating. There has been much negative press about fluoride, especially its placement in municipal water supplies by local and regional governments. However, studies have shown that limited use in toothpaste is not a problem. Certain individuals, especially children, can get too much fluoride, which can cause dental fluorosis, a discoloring of the teeth. Thus children should be supervised when using fluoridated toothpaste, lest they eat it and become susceptible.28 However, the amounts required are fairly large, so fluorosis is not very common. Allegations concerning other problems - remember General Jack D. Ripper in Kubrick's Dr Strangelove? - are unfounded. Advocates of fluoride in toothpaste span the natural spectrum from Dr Andrew Weil to Tom's of Maine.
Toothpastes are mixtures of many ingredients. A good toothpaste is likely to use polishing agents, such as calcium carbonate and colloidal silica; emulsifying agents (to help raise particles stuck to the surface of teeth); anticaries agents, such as fluoride; tartar-control ingredients, such as a natural phenolic-rich menthol, an antioxidant; pH buffers; humectants (agents that prevent dry-out, increase saliva, and improve what is known as mouth-feel); and whiteners, such as aqua. Toothpaste can be designed in accordance with the latest research, emphasizing the use of natural ingredients. It should also contain an extract from the Hamamelis virginiana bark (from which witch hazel is made), which has been shown to exhibit significant antiviral activity against Herpes simplex virus type 1.29 Hamamelis also exhibits free-radical scavenging activities and possesses antiinflammatory and antihemorrhagic properties (it helps stop oral bleeding).30
These ingredients are state-of-the-art for an efficient means to ward off the kinds of bacteria that have made the history of dentistry so excruciating. And as we now know, these bacteria are strongly suspected of playing a role in fomenting other degenerative diseases as well (see Discovering Antibacterial Mastic - Page 1 - April 1999). Moreover, mastic toothpaste can help increase the quality of nature's bacteria-fighting enzymes in your saliva and marshal your body's defense system, while it brightens your smile and sweetens your breath.
© Copyright 1999 Life Enhancement Products, Inc. All Rights Reserved.
- Ripamonti U. Paleopathology in Australopithecus africanus: a suggested case of a 3-million-year-old prepubertal periodontitis. Am J Phys Anthropol 1988 Jun;76(2):197-210.
- Mitsis FJ, Taramidis G. Alveolar bone loss on Neolithic man remains on 38 skulls of Khirokitia's (Cyprus) inhabitants. J Clin Periodontol 1995 Oct;22(10):788-93.
- Kerr NW. The prevalence and natural history of periodontal disease in Britain from prehistoric to modern times. Br Dent J 1998 Nov 28;185(10):527-35.
- Xu Y, MacEntee MI. The roots of dentistry in ancient China. J Can Dent Assoc 1994 Jul;60(7):613-6.
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- Ramos Calvo PM, Gioriena de Gandarias FJ, Rodriguez Baciero G. Dentistry in antiquity. Egypt, Hippocrates, Galen and Celsus. Rev Esp Estomatol 1986 Nov-Dec;34(6):427-36.
- Meyerhof, Max. Studies in Medieval Arabic Medicine: Theory and Practice, ed. by P. Johnstone. London: Variorum Reprints, 1984.
- Uzel I. Dental chapters of Serefeddin Sabuncuoglu's (1385-1468?) illustrated surgical book Cerrahiyyetu'l Haniyye. J Hist Dent 1997 Nov;45(3):107-12.
- Riera JD.The odontological chapter in the surgical work of Abulcasis. Ann Esp Odontoestomatol 1967 Jul-Aug;26(4):319-24.
- Wynbrandt J. The Excruciating History of Dentistry: Toothsome Tales & Oral Oddities from Babylon to Braces. St Martins Press: New York, 1998.
- Shklar G. Leeuwenhoek and Vermeer, an association of genius. J Hist Dent 1998 Jul;46(2):53-7.
- Mandel ID. Why pick on teeth? J Am Dent Assoc 1990 Jul;121(1):129-32.
- Neiburger EJ, Cohen M, Lieberman J, Lieberman M. The dentition of Abraham's people. Why Abraham left Mesopotamia. N Y State Dent J 1998 Nov;64(9):25-9.
- Holtkamp P. Toothpick - an historical requisite. Quintessenz J 1988 Sep;18(9):903-6.
- Travers B, McGrath K, eds. World of Invention. Gale Research, Inc.,1994.
- Al-Razi (Rhazes). A Treatise on the Smallpox and Measles by Abu Becr Mohammed ibn Zacariya ar-Razi (commonly called Rhazes), transl. by W. A. Greenhill. London: Sydenham Society, 1847.
- Okuda K, Ebihara Y. Relationships between chronic oral infectious diseases and systemic diseases. Bull Tokyo Dent Coll 1998 Aug;39(3):165-74.
- Perikos J. The Chios Gum Mastic. Print All Ltd: Athens, 1993.
- Topitsoglou-Themeli V, Dagalis P, Lambrou D A Chios mastiche chewing gum and oral hygiene. I. The possibility of reducing or preventing microbial plaque formation. Hell Stomatol Chron 1984 Jul-Sep;28(3):166-70.
- Featherstone JD. Prevention and reversal of dental caries: role of low level fluoride. Community Dent Oral Epidemiol 1999 Feb;27(1):31-40.
- Linossier A, Gajardo M, Olavarria J. Paleomicrobiological study in dental calculus: Streptococcus mutans. Scanning Microsc 1996;10(4):1005-13; discussion 1014.
- Limeback H. A re-examination of the pre-eruptive and post-eruptive mechanism of the anti-caries effects of fluoride: is there any anti-caries benefit from swallowing fluoride? Community Dent Oral Epidemiol 1999 Feb;27(1):62-71.
- Triller M. Fluoride, a preventive agent of caries: mechanisms, sources, risks. Arch Pediatr 1998 Oct;5(10):1149-52.
- Erdelmeier CA, Cinatl J Jr, Rabenau H, Doerr HW, Biber A, Koch E. Antiviral and antiphlogistic activities of Hamamelis virginiana bark. Planta Med 1996 Jun;62(3):241-5.
- Duwiejua M, Zeitlin IJ, Waterman PG, Gray AI. Anti-inflammatory activity of Polygonum bistorta, Guaiacum officinale and Hamamelis virginiana in rats. J Pharm Pharmacol 1994 Apr;46(4):286-90.