Chemistry in Oral Health prepared by J. Chem. Educ. Staff
0 What's in Toothpaste?
Table 1. Ratings of Toothpaste Abrasiveness" (Listed in Order of Increasing Abrasiveness)
All dentifrices-toothpastes, gels, and powders-contain a t least four types of ingredients: abrasives, sudsers, sweetening agents and flavoring agents. Many contain other ingredieuts-such as fluoride, whiteners, moisture-retainers, softeners and binding agents. Among the abrasives used are CaHPOa NaP08 CaCO, calcium hydrogen sodium calcium phosphate metsphos~hate carbonate Mafinesium carbonate, hydrated aluminum oxidrs, silicates. and silica rvl alsoare usnl. Abrasives remow dehris and stains from teeti; by polishing. T h e American Dental Association and the American Pharmaceutical Association rate toothpastes on their average abrasivity. Table 1gives the abrasiveness ratings for some common brands. Tooth enamel is the hardest substance produced by the human body. The abrasives used in dentifrices do not appear to wear away much of the tooth enamel. Commonly used sudsers are the detergents sodium lauryl sulfate and sodium N-lauroyl sarcosinate. Sudsers also act as cleansers (detergents).
CH,(CH,),,,-C-N-CH?-CO%+
I
I1
CH, sodium N-lauroyl sarcosinate
I
i
CH C H , '
CH
' C H , Menthol
Product
Llsterine
26
Ultra Brite
64
Pepsodant (with zircmium silicate) Coigate (with MFPI
26
Macleans (spearmint)
51
Pearl Drops
Product
Average Abrb sivity
81
66
Crest (mint) Close-up
72
Gleem il
106
87
soft, and sodium perborate is added in certain products to enhance whitening and to assist in removing stains.
CHOH
I
NaH,RO, sodium perhorate
CHOH glycerin (glycerol)
CH ,-(CH,!),,,-CH., nonadecane component of mineral oil
Common Dental Problems
Saccharin is the most commonly used sweetening agent, though others may be substituted for it because of recent concern over its possible toxicity. Addition of sugar is discouraged hy dental authorities because it is a key cause of cavities. Flavors such as spearmint, peppermint, wintergreen, and sassafras are choices of most manufacturers.
Saccharin
Product
Average Abrasivity
Advertisements making claims on "whitening" and "brightening" of teeth can he misleading. The teeth of many are simply not white and no commercial product can change this. Brushing with a good dentifrice can remove stains and polish the teeth, however.
sodium lauryl sulfate
0
Average AbrasiviW
(.H/
'CH,
Menthone
maim components of oil of peppermint
The two most prevalent dental diseases are tooth decay (dental caries) and gum inflammation (periodontal disease). Both can result in tooth loss-caries through disintegration or extraction, periodontal disease by destruction of gum tissue which supports the tooth in its socket. Both diseases have been indisputably linked to dental plaque. Plaque is a soft film that forms readily and holds tenaciouslv on tooth surfaces. It consists chieflv of hacteria and bacterial products. Within minutes aft& a tooth is cleaned. a film composed of protein from saliva is deposited. ~icro-organisms,mostly st~eptococcusrnutons and streptococcus sanguis adhere to the film and begin tomultiply. The hacteria and their products, carbohydrates and proteins, are the chief constituents of plaque. Under proper conditions, plaque can slowly absorb calcium salts, and become transformed into a hard material known as dental calculus. Dental caries can form when sugars are absorbed into the plaque and are metabolized by the bacteria present producing acids which, in time, erode the tooth enamel. Lactic acid
Glycerin is added to keep toothpaste from drying out too rapidly when exposed to air. Mineral oil is added to keep it
r
/
A detailed article on the develonment of diohosohonates
736 I Journal of Chemical Education
I
appears to cause the greatest damage, though pyruvic and acetic acids also are present. In effect, the acid creates chemical conditions that cause calcium ions in tooth enamel to slowly dissolve in saliva.
Peridontal disease appeam to begin a t the interface between plaque and the gums (gingiva). Products from bacteria in plaque cause inflammation of the gums. To rid themselves of the hacteria and their products, the gums marshall a host of chemicals to destroy the bacteria. If these chemicals are present in large enough quantities and over a long enough period, they also can destroy gum tissue and the fibers that hold teeth in place.
The Role of Fluoride Research has shown convincinelv that routine use of fluoride-containing dentifrices (in particular, those that contain stannous fluoride, SnF2, or sodium monofluorophosphate, Na2P03F,) can reduce the rate of caries formation in young and old alike. The use of sodium fluoride. NaF, for this purpose has been less successful. Evidence available suggests that, in the chemical environment of the teeth, fluoride ion can react with the key component of tooth enamel, hydroxyapatite, Caln(P04)n(OH)2,to form an extremely thinlayer ofdensely p&kedparticl& of calcium fluoride, CaF2, and stannous phosphate, Sns(PO&. This layer forms an effective protective surface film on dental enamel. Fluoride-containing dentifrices approved hy the American Dental Association or accepted by Consumer's Union are listed in Table 2. Table
2.
damaging when taken in liquids, for example) 5) regular visits with dentist
Mouthwashes Mouthwashes sold without prescription are essentially dilute solutions of breath-perfumingsubstances that often are sweetened with saccharin and colored to sell. Many contain ethanol and antibacterial agents. The Council on Dental Therapeutics of the ADA has said it "finds no substantial contribution to oral health in the unsupervised use of medicated mouthwashes by the general public."
Adhesive Sealants The painting of teeth with polymeric or plastic adhesive sealants has resulted in reports that these afford 80% or better ~rotectionaeainst caries. However. the ~ a i n t i n eDrocess is eostly and &st be repeated a t six'monih inter&ls. Three tvDes .. of sealants have been successfullv used: cvanoacrvlates. polyurethane materials and a polymer formed with h~spht!nol A, glyridgl merharrylate, and methylmethacrylate.
portion of a cyanoacrylate adhesive sealant
Fluoride Dentifrices Accepted by American Dental Association or Consumer's Union
ADA Accepted Colgate, with Gardol plus MFP fluoride Crest, with Fluoristan, mint flavor Crest, with Fluoristan, regular
CU Accepted A8P Fluoride Gleem 11, New Special Formula, New Special Brightnerr Rexall Fluoride Safeway Fluoride Worthmore Stannous Fluoride
Proper Oral Health Care Although toothpastes help in scrubbing and cleaning, and are therefore an aid in plaque control, the toothbrush and the way it is used are far more important. The ADA recommends a five-part program of dental care regular and effectivebrushing with a suitable toothbrush 2) daily use of unwaved dental floss 3) forced rinsing of teeth and mouth after eating 1)
4) proper nutrition including sensible sugar intake (sugar is less
portion of a polyurethane sealant
Possibilities for the Future Work now is underway to develop even more effective preventatives for dental caries and periodontal diseases. Some promising approaches are
References (1) Handbook of NonprescriptionDrugs, American Pharmaceutical Associatim. 5th ed., 1977. (2) Cornacchia.Hamldd.,"Consumer Hesith."Maby,SL Louis, 1976. (3) Brown.W. E.."Oral Health, Dentirtryand tho American Public,"UniversityofOkia~ homa Plesa. Nurman, 1974.
Volume 55, Number 11. November 1978 / 737
