Toothpaste

Toothpaste from a tube being applied to a toothbrush

Toothpaste is a paste or gel dentifrice used with a toothbrush as an accessory to clean and maintain the aesthetics and health of teeth. Toothpaste is used to promote oral hygiene: it serves as an abrasive that aids in removing the dental plaque and food from the teeth, assists in suppressing halitosis, and delivers active ingredients (most commonly fluoride) to help prevent tooth decay (dental caries) and gum disease (gingivitis).^[1] Salt and sodium bicarbonate (baking soda) are among materials that can be substituted for commercial toothpaste. Toothpaste is not intended to be swallowed due to the fluoride content, but is generally not very harmful if accidentally swallowed in small amounts; however, one should seek medical attention after swallowing abnormally large amounts.^[2]

Ingredients

In addition to 20–42% water, toothpastes are derived from a variety of components, the three main ones being abrasives, fluoride, and detergents.

Abrasives

Abrasives constitute at least 50% of a typical toothpaste. These insoluble particles help remove plaque from the teeth. The removal of plaque and calculus helps minimize cavities and periodontal disease. Representative abrasives include particles of aluminum hydroxide (Al(OH)₃), calcium carbonate (CaCO₃), various calcium hydrogen phosphates, various silicas and zeolites, and hydroxyapatite (Ca₅(PO₄)₃OH).

Abrasives, like the dental polishing agents used in dentists' offices, also cause a small amount of enamel erosion which is termed "polishing" action. Some brands contain powdered white mica, which acts as a mild abrasive, and also adds a cosmetically pleasing glittery shimmer to the paste. The polishing of teeth removes stains from tooth surfaces, but has not been shown to improve dental health over and above the effects of the removal of plaque and calculus.^[3]

The abrasive effect of toothpaste is indicated by its RDA value. Too high RDA values should be considered critical, and some dentists recommend toothpaste of an RDA value no higher than 50 for daily use.

Fluorides

Fluoride in various forms is the most popular active ingredient in toothpaste to prevent cavities. Fluoride occurs in small amounts in plants, animals, and some natural water sources. The additional fluoride in toothpaste has beneficial effects on the formation of dental enamel and bones. Sodium fluoride (NaF) is the most common source of fluoride, but stannous fluoride (SnF₂), olaflur (an organic salt of fluoride), and sodium monofluorophosphate (Na₂PO₃F) are also used. Stannous fluoride has been shown to be more effective than sodium fluoride in reducing the incidence of dental caries^[4] and controlling gingivitis, but causes somewhat more surface stains.^[5]

Much of the toothpaste sold in the United States has 1,000 to 1,100 parts per million fluoride. In European countries, such as the UK or Greece, the fluoride content is often higher; a NaF content of 0.312% w/w (1,450 ppm fluoride) is common.

Surfactants

Many, although not all, toothpastes contain sodium lauryl sulfate (SLS) or related surfactants (detergents). SLS is found in many other personal care products, as well, such as shampoo, and is mainly a foaming agent, which enables uniform distribution of toothpaste, improving its cleansing power.^[3]

Despite the different ingredients included in the toothpaste, recent study (meta analysis) indicates that brushing with or without toothpaste has no impact on the level of plaque removal.^[6]

Other components

Antibacterial agents

Triclosan, an antibacterial agent, is a common toothpaste ingredient in the United Kingdom. Triclosan or zinc chloride prevent gingivitis and, according to the American Dental Association, helps reduce tartar and bad breath.^[1][7] A 2006 review of clinical research concluded there was evidence for the effectiveness of 0.30% triclosan in reducing plaque and gingivitis.^[8]

Flavorants

Toothpaste comes in a variety of colors, and flavors intended to encourage use of the product. Three most common flavorants are peppermint, spearmint, and wintergreen. Toothpaste flavored with peppermint-anise oil is popular in the Mediterranean region. These flavors are provided by the respective oils, e.g. peppermint oil.^[3] More exotic flavors include Anethole anise, apricot, bubblegum, cinnamon, fennel, lavender, neem, ginger, vanilla, lemon, orange, and pine. Alternatively, unflavored toothpastes exist.

Remineralizers

Hydroxyapatite nanocrystals and a variety of calcium phosphates are included in formulations for remineralization,^[9] i.e. the reformation of enamel.

Toothpaste is sold in many brands.

Miscellaneous components

Agents are added to suppress the tendency of toothpaste to dry into a powder. Included are various sugar alcohols, such as glycerol, sorbitol, or xylitol, or related derivatives, such as 1,2-propylene glycol and polyethyleneglycol.^[10] Strontium chloride or potassium nitrate is included in some toothpastes to reduce sensitivity. Sodium polyphosphate is added to minimize the formation of tartar.

Safety

Fluoride

Although water fluoridation has been praised as one of the top medical achievements of the 20th century,^[11] fluoride-containing toothpaste can be acutely toxic if swallowed in large amounts.^[12][13] Approximately 15 mg/kg body weight is the acute lethal dose, even though as small amount as 5 mg/kg may be fatal to some children.^[14]

Risk of using fluoride is low enough that the use of full-strength toothpaste (1350–1500 ppm fluoride) is advised for all ages (although smaller volumes are used for young children; a smear of toothpaste until three years old).^[13] A major concern of dental fluorosis is for children under 12 months ingesting excessive fluoride through toothpaste. Nausea and vomiting are also problems which might arise with topical fluoride ingestion.^[14]

Diethylene glycol

The inclusion of sweet-tasting but toxic diethylene glycol in Chinese-made toothpaste led to a recall in 2007 involving multiple toothpaste brands in several nations.^[15] The world outcry made Chinese officials ban the practice of using diethylene glycol in toothpaste.^[16]

Triclosan

Reports have suggested triclosan, an active ingredient in many kinds of toothpastes, can combine with chlorine in tap water to form chloroform,^[17] which the United States Environmental Protection Agency classifies as a probable human carcinogen. An animal study revealed the chemical might modify hormone regulation, and many other lab researches proved bacteria might be able to develop resistance to triclosan in a way which can help them to resist antibiotics also.^[18]

Miscellaneous issues and debates

With the exception of toothpaste intended to be used on pets such as dogs and cats, and toothpaste used by astronauts, most toothpaste is not intended to be swallowed, and doing so may cause nausea or diarrhea. Tartar fighting toothpastes have been debated.^[19] Case reports of plasma cell gingivitis have been reported with the use of herbal toothpaste containing cinnamon.^[20] SLS has been proposed to increase the frequency of mouth ulcers in some people, as it can dry out the protective layer of oral tissues, causing the underlying tissues to become damaged.^[21]

Alteration of taste perception

After using toothpaste, orange juice and other juices have an unpleasant taste. Sodium lauryl sulfate alters taste perception. It can break down phospholipids that inhibit taste receptors for sweetness, giving food a bitter taste. In contrast, apples are known to taste more pleasant after using toothpaste.^[22] Distinguishing between the hypotheses that the bitter taste of orange juice results from stannous fluoride or from sodium lauryl sulfate is still an unresolved issue and it is thought that the menthol added for flavor may also take part in the alteration of taste perception when binding to lingual cold receptors.

Other types of toothpaste

Whitening toothpastes

Many toothpastes make whitening claims. Some of these toothpastes contain peroxide, the same ingredient found in tooth bleaching gels. The abrasive in these toothpastes, not the peroxide, removes the stains.^[23] Whitening toothpaste cannot alter the natural color of teeth or reverse discoloration by penetrating surface stains or decay. To remove surface stains, whitening toothpaste may include abrasives to gently polish the teeth or additives such as sodium tripolyphosphate to break down or dissolve stains. When used twice a day, whitening toothpaste typically takes two to four weeks to make teeth appear whiter. Whitening toothpaste is generally safe for daily use, but excessive use might damage tooth enamel. Teeth whitening gels represent an alternative.^[24] However, the whitening process can permanently reduce the strength of the teeth, as the process scrapes away a protective outer layer of enamel.^[25]

Herbal and natural toothpastes

Companies such as Tom's of Maine, among others, manufacture natural and herbal toothpastes and market them to consumers who wish to avoid the artificial ingredients commonly found in regular toothpastes. Many herbal toothpastes do not contain fluoride or sodium lauryl sulfate. The ingredients found in natural toothpastes vary widely but often include baking soda, aloe, eucalyptus oil, myrrh, plant extract (strawberry extract), and essential oils.

According to a study by the Delhi Institute of Pharmaceutical Sciences and Research, many of the herbal toothpastes being sold in India were adulterated with nicotine.^[26]

Striped toothpaste

The red area represents the material used for stripes, and the rest is the main toothpaste material. The two materials are not in separate compartments; they are sufficiently viscous that they will not mix. Applying pressure to the tube causes the main material to issue out through the pipe. Simultaneously, some of the pressure is forwarded to the stripe-material, which is thereby pressed onto the main material through holes in the pipe.

Striped toothpaste was invented by a New Yorker named Leonard Lawrence Marraffino in 1955. The patent (US patent 2,789,731, issued 1957) was subsequently sold to Unilever, who marketed the novelty under the Stripe brand-name in the early 1960s. This was followed by the introduction of the Signal brand in Europe in 1965 (UK patent 813,514). Although Stripe was initially very successful, it never again achieved the 8% market share that it cornered during its second year.

Marraffino's design, which remains in use for single-color stripes, is simple. The main material, usually white, sits at the crimp end of the toothpaste tube and makes up most of its bulk. A thin pipe, through which that carrier material will flow, descends from the nozzle to it. The stripe-material (this was red in Stripe) fills the gap between the carrier material and the top of the tube. The two materials are not in separate compartments, however they are sufficiently viscous that they will not mix. When pressure is applied to the toothpaste tube, the main material squeezes down the thin pipe to the nozzle. Simultaneously, the pressure applied to the main material causes pressure to be forwarded to the stripe material, which thereby issues out through small holes (in the side of the pipe) onto the main carrier material as it is passing those holes.

In 1990 Colgate-Palmolive was granted a patent (USPTO 4,969,767) for two differently colored stripes. In this scheme, the inner pipe has a cone-shaped plastic guard around it, and about halfway up its length. Between the guard and the nozzle-end of the tube is a space for the material for one color, which issues out of holes in the pipe. On the other side of the guard is space for second stripe-material, which has its own set of holes.

Striped toothpaste should not be confused with layered toothpaste. Layered toothpaste requires a multi-chamber design (e.g. USPTO 5,020,694), in which two or three layers extrude out of the nozzle. This scheme, like that of pump dispensers (USPTO 4,461,403), is more complicated (and thus, more expensive to manufacture) than either the Marraffino design or the Colgate design.

History

Early toothpastes

Since 5000 BC, the Egyptians made a tooth powder, which consisted of powdered ashes of ox hooves, myrrh, powdered and burnt eggshells, and pumice. The Greeks, and then the Romans, improved the recipes by adding abrasives such as crushed bones and oyster shells.^[27] In the 9th century, Iraqi musician and fashion designer Ziryab invented a type of toothpaste, which he popularized throughout Islamic Spain.^[28] The exact ingredients of this toothpaste are unknown,^[29] but it was reported to have been both "functional and pleasant to taste".^[28] It is not known whether these early toothpastes were used alone, were to be rubbed onto the teeth with rags, or were to be used with early toothbrushes, such as neem-tree twigs and miswak. Toothpastes or powders came into general use in the 19th century.

Tooth powder

Tooth powders for use with toothbrushes came into general use in the 19th century in Britain. Most were homemade, with chalk, pulverized brick, or salt as ingredients. An 1866 Home Encyclopedia recommended pulverized charcoal, and cautioned that many patented tooth powders that were commercially marketed did more harm than good.

Arm & Hammer marketed a baking soda-based toothpowder in the United States until approximately 2000, and Colgate currently markets toothpowder in India and other countries.

Modern toothpaste

Modern toothpaste gel

An 18th-century American and British toothpaste recipe called for burned bread. Another formula around this time called for dragon's blood (a resin), cinnamon, and burned alum.^[30]

By 1900, a paste made of hydrogen peroxide and baking soda was recommended for use with toothbrushes. Pre-mixed toothpastes were first marketed in the 19th century, but did not surpass the popularity of tooth-powder until World War I. In 1880, Doctor Washington Sheffield of New London, CT manufactured toothpaste into a collapsible tube, Dr. Sheffield's Creme Dentifrice. He had the idea after his son traveled to Paris and saw painters using paint from tubes. In York in 1896, Colgate & Company Dental Cream was packaged in collapsible tubes imitating Sheffield. The original collapsible toothpaste tubes were made of lead.^[31][32]

Promotional poster for the Kolynos toothpaste from the 1940s

Together with Willoughby D. Miller, Newell Sill Jenkins developed a toothpaste and named it Kolynos, the first toothpaste containing disinfectants.^[33] The name's origin is from Greek Kolyo nosos (κωλύω νόσος), meaning "disease prevention". Numerous attempts to produce the toothpaste by pharmacists in Europe have been uneconomic. After returning to the US, he continued experimenting with Harry Ward Foote (1875-1942), professor of chemistry at Sheffield Chemical Laboratory of Yale University.^[34] After 17 years of development of Kolynos and clinical trials Jenkins retired and transferred the production and distribution to his son Leonard A. Jenkins, who brought the first toothpaste tubes on the market on April 13, 1908. Within a few years the company expanded in North America, Latin America, Europe and the Far East. A branch operation opened in London in 1909. In 1937 Kolynos was produced in 22 countries and sold in 88 countries. Until modern times Kolynos is widespread mainly in South America and in Hungary. Colgate-Palmolive took over the production of American Home Products in 1995 at a cost of one billion US dollars.^[35]

Colgate Dental Cream (Toothpaste) With Gardol - ca. 1950s

Fluoride was first added to toothpastes in the 1890s. Tanagra, containing calcium fluoride as the active ingredient, was sold by Karl F. Toellner Company, of Bremen, Germany, based upon the early work of chemist Albert Deninger.^[36] An analogous invention by Roy Cross, of Kansas City, Missouri, was initially criticized by the American Dental Association (ADA) in 1937. Fluoride toothpastes developed in the 1950s received the ADA's approval. To develop the first ADA-approved fluoride toothpaste, Procter & Gamble started a research program in the early 1940s. In 1950, Procter & Gamble developed a joint research project team headed by Dr. Joseph Muhler at Indiana University to study new toothpaste with fluoride. In 1955, Procter & Gamble's Crest launched its first clinically proven fluoride-containing toothpaste. On August 1, 1960, the ADA reported that "Crest has been shown to be an effective anticavity (decay preventative) dentifrice that can be of significant value when used in a conscientiously applied program of oral hygiene and regular professional care."

In 2006 BioRepair appeared in Europe with the first toothpaste containing synthetic hydroxylapatite as an alternative to fluoride for the remineralization and reparation of tooth enamel. The "biomimetic hydroxylapatite" is intended to protect the teeth by creating a new layer of synthetic enamel around the tooth instead of hardening the existing layer with fluoride that chemically changes it into fluorapatite.^[37]

In June 2007, the US Food and Drug Administration (FDA) and similar agencies in Panama, Puerto Rico and Australia advised consumers to avoid certain brands of toothpaste manufactured in China after some were found to contain the poisonous diethylene glycol, also called diglycol or labeled as "DEG" on the tube.^[38]

See also

• Dental floss
• Fluoride therapy
• List of toothpaste brands

References

External links

Wikimedia Commons has media related to Toothpaste.

• Chemistry of Plaque Prevention with Toothpaste
• Fluoride toothpaste history