Clinical Feature

Soft Drinks: Hard on Teeth

With soda pop decay contributing to an alarming increase in caries among young people, dentistry finds itself fighting another kind of access problem: sweetened beverages within reach 24 hours a day.

Pamela R. Erickson, D.D.S., Ph.D.*, more than 27% of Americans’ beverage Deanna L.Alevizos, D.D.S., M.S.**, consumption.1 In 1997, Americans *Dr. Erickson is a pediatric dentist in and Darcy J. Rindelaub, D.D.S.*** spent more than $54 billion to buy 14 private practice in Minnetonka, billion gallons of soft drinks. Today Minnesota. She is the immediate past- oft drinks are popular Americans consume more than 56 president of the Minnesota Association beverages. These cool, bubbly gallons per year,or more than one-and- of Pediatric Dentistry. drinks are being consumed a-half 12 ounce cans per day for every ** Dr.Alevizos is a pediatric dentist in everywhere. In fact, you may man, woman, and child. private practice. She is a 2000 gradu- very well have a can sitting Dentists are becoming increasingly ate of the University of Minnesota nextS to you as you read this article. In concerned that over-consumption of School of Dentistry. the , it is culturally accept- soft drinks may result in greater able to consume soft drinks any time amounts of dental disease. In a letter ***Dr. Rindelaub is a second year pedi- of the day. copied in the December 1997 Journal of atric dentistry resident at the University Carbonated soft drinks account for the American Dental Association,Dr. Paul of Minnesota School of Dentistry.

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Readhead from Ames,Iowa was curious dentin, leaving the outer 20- to 50- easily penetrated and dissolved by to know if any other dentist had micrometer-thick surface preserved acids.4 Even in the absence of carbohy- noticed significant increase in decay more or less intact.3 drates, soft drinks can be destructive to among teenagers and adults due to With the consump- teeth.These acidic, or low patients drinking either regular or diet tion of acidic, carbohy- pH, beverages can con- Coke® or ®.Dr. Readhead noticed, drate-rich soft drinks, Children tribute to the demineral- looking at the ingredients of the soft teenagers are at high start con- ization of dental hard drinks, that most of them, especially the risk for caries develop- tissues. , contain phosphoric acid, and ment, which can be suming soft Dental erosion is the loss some, citric acid. The patients he had quite aggressive (Figure drinks at a of tooth structure by a identified who were experiencing this 1). Eight- to 17-year-old chemical process not decay were noted to have had above children are at greatest remarkably involving bacteria.5 Initially, average oral hygiene and very little risk. Normally, as the young enamel will demineralize previous decay. young, immature enamel and dissolve, with the sur- is bathed by salivary ions age... face appearing dull. Acids Acid Versus Enamel and the intercrystalline can also enter the pits and It is well known by the medical profes- spaces fill, it becomes progressively pores of enamel and cause subsurface sion that disease loves acid,2 and this is harder and more mature. Mature structure loss.6 The solubility of particularly true of dental caries. enamel appears as a very dense, less hydroxyapatite increases logarithmi- Dental caries, by definition, is tooth penetrable, glassy hard structure that is cally with decreasing pH. demineralization caused by acidic fairly resistant to acid attack. Erosion may be caused by either byproducts of the bacterial fermenta- However, enamel maturation takes intrinsic or extrinsic sources. The tion of dietary . The resulting time. The newly erupted enamel in intrinsic causes have been documented caries lesion involves gradual deminer- teenagers is immature, and the crys- to include cases of anorexia nervosa alization of subsurface enamel and talline structure is porous, chalky, and and bulimia, as well as any gastrointesti- nal disorder that involves increased outputs of gastric acids. Extrinsic Figure 1. sources include acidic medicines such as vitamin C and aspirin, aerosol acid chemicals in the work environment, or the frequent consumption of acid food- stuffs or drinks. Simple pH monitors have shown that all types of soft drinks are very acidic, especially the colas, which can have a pH of 2.4 or less (Table I). In order to neutralize a glass of , it takes 32 glasses of high pH alkaline water.2 Exposure of enamel to Coca-Cola® for one hour leads to significant reduction in microhardness, and scanning electron microscopic evaluation has revealed surface irregularities.7

Soft Drink Consumption Photograph of a 16-year, two-month-old male with rampant caries secondary to Children start consuming soft drinks at consumption.This teenager presented for consultation after referral from a remarkably young age, and consump- a general dentist.The previous dental examination at 14 years, five months of age tion increases through young adult- showed no dental caries. Contributing etiology was the consumption of three to four cans of per day while at school. Patient reported starting to hood. Twenty percent of one- consume these large quantities upon entering high school, where vending machines and two-year-old children consume were readily available. soft drinks.8 Those toddlers drink an

16 Northwest Dentistry average of seven ounces — nearly one from 72% in 1977-79 to 57% in 1994.10 teenagers. Furthermore, children who cup — per day. Data from national surveys indicate consume more than 26 ounces of soft The consumption of soft drinks has that calcium intakes of a drinks per day were four increased in the United States over considerable propor- times more likely to con- the past decades. United States tion of U.S. children, Milk con- sume less than eight Department of Agriculture Food teenagers in particular, ounces of milk per day.14 Consumption Surveys (1977-1978, are well below the sumption Nearly a tenth of the 1987-88, 1994-96) have found that Recommended Daily has dropped calories consumed by almost half of all children between six Allowance (RDA).11 For American teenagers and eleven years of age consume soft instance, data from a in children come from nutrition- drinks, with the average child consum- 1989 survey indicated over this ally empty sodas, ing 15 ounces per day, up slightly from that just 39.5% of girls which they drink at the 12 ounces in 1977-78. The most avid aged 12-18 were con- same expense of calcium rich consumers are 12- to 29-year-old suming 75% or more of period. milk. As a result, many males. Boys between 12 and 19 years of the RDA for calcium.12 young Americans today age who consume soft drinks take in an Guenther13 found that are reaching the age of average of almost two 12 ounce sodas soft drink intake was negatively associ- maximum bone growth with bones (28.5 ounces) per day. Teenage girls ated with milk, calcium, magnesium, vit- highly prone to osteoporosis. also drink large amounts (20 amin A, and vitamin C intake in U.S. Soft drinks and have ounces/day), although slightly less than their male counterparts. Table I. Another analysis9 found that one fourth of males 13 to 18 years old pH and Content of a Variety of Soft Drinks and Other drank two or more cans of soft drinks Popular Beverages. a day, while one out of 20 drank five or Sugar Sugar more cans per day. One-fourth of Beverage pH (gm/serving) Beverage pH (gm/serving) 13- to 18-year-old females drank two Coca-Cola 3.12 50 Classic 2.53 39 cans per day, and one out of 20 drank 2.85 40 three or more cans per day. Diet 3.39 0 Cherry 2.53 42 Orange Soda 2.80 47 Nutritional Impact 3.42 26 ’s Soft drink vending machines have 3.02 46 added to this substantial increase in Iced Tea 3.86 22 soft drink consumption. Comparison 7-Up Iced Tea 2.90 33 Regular 3.19 26 of the results of the 1965-66 USDA Iced Tea 3.04 22 Diet 3.67 0 Food Consumption Survey with those Pepsi one decade later showed that the Cooler 2.97 14 Regular 2.49 42 percentage of toddlers who consumed Lemon Lime 2.97 14 soft drinks increased from 30% to Diet 3.05 0 40%. Furthermore, in the 1977-78 Mountain Dew Plain Tea 3.93 25 survey, the typical (50th percentile) Regular 3.22 31 Lemon Iced Tea 2.98 25 teenager drank about one half of Diet 3.34 0 Pink 2.54 26 the current consumption. Data from Dr. Pepper the USDA surveys indicate that the Diet Pink Regular 2.92 27 Lemonade 3.10 0 proportion of adolescent boys and Diet 3.41 0 girls consuming soft drinks on any Lemonade 2.56 30 given day increased by 74% and 65%, Barq’s Root Beer Diet Lemon respectively.10 Regular 4.61 45 Iced Tea 2.55 0 Concomitantly, milk consumption Diet 4.55 0 Raspberry has dropped in children over this same A&W Root Beer 4.41 31 Iced Tea 2.95 29 period. For example, the proportion of 3.46 0 adolescent girls drinking milk dropped

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minimal nutritional content. All contain sustains a neonate’s preference for million on , while the four negligible amounts of the RDA for sweets.18 Studies have shown that major soft drink companies spent vitamins, minerals, and protein.14 sweet preference changes with expo- $631 million. Between 1986 and 1997, Nutritionists warn that sweetened bev- sure to sugars,19 and the these companies spent erages can curb a child’s appetite and more sugars people con- $6.8 billion on adver- displace protein and calcium rich foods sume, the higher their tising.8 needed for proper growth. threshold for sweetness, Soft drink Companies make sure High soft drink consumption can also indicating an increased manufactur- that their products are lead to excessive energy (caloric) risk for caries. always readily available. intake, which may contribute to child- ers market Thus, in 1997, 2.8 million hood obesity, a growing problem Marketing and sell soft drink vending among our children.15 Sodas are the Soft drink companies machines dispensed 27 largest single source of added sugars. market their products by their billion drinks worth A 12-ounce soft drink contains on sending the message that products by $17.5 billion.20 Coca- average 150 dietary calories. The per- soft drinks are healthy to Cola® soft drinks are centage of overweight youths aged 6 to consume at all times of contracting sold at two million 17 years has more than doubled in the the day. A quote from M. with school stores, more than past 30 years.16 It is estimated that Douglas Ivester, Coca- 450,000 restaurants, and approximately 11% of U.S. youths are Cola’s® chairman and systems. 1.4 million vending now seriously overweight.16 CEO, defending marketing machines.21 Food acceptance by young children in Africa, said, “...actually, has been shown to be largely depen- our product is quite healthy. Fluid The School Connection dent upon two characteristics: sweet- replenishment is a key to health. . . One of the ways that soft drink manu- ness and familiarity.17 There is evidence Coca-Cola® does a great service facturers market and sell their products that continuous exposure to sweets because it encourages people to take in is by contracting with school systems. more and more liquids.”8 Pepsi® and Coca-Cola® are the two The soft drink industry has consis- main contractors in schools.22 For Soft Drinks are Hard on tently portrayed its products as being example, in November 1997, one of Teeth: Minimize the Risk positively healthful, saying they are Colorado’s largest school districts ® • Drink carbonated soft drinks and 90% water and contain sugars found entered into a partnership with Pepsi 8 ® sweetened liquids (like fruit ) in nature. A poster provided to teach- and U.S. West to build a five million in moderation. ers by the National Soft Drink dollar football stadium. Within the Association states: agreement, Pepsi® obtained exclusive • Drink fluoridated water and use a “As refreshing sources of needed liq- rights to sell its products in the dis- fluoride toothpaste. uids and energy, soft drinks represent a trict’s 140 schools. • Swish out your mouth with water positive addition to a well-balanced Soft drink company partnerships to dilute the sugar and acid. diet. . . These same three sugars also have become so commercial that there • Use a straw to keep sugars and occur naturally, for example, in . . . have been letters sent from school acids away from your teeth. In your body it makes no difference officials in Colorado to their schools • Never consume soft drinks or whether the sugar comes from a soft warning them that if their school didn’t juice at bedtime. (The liquid pools drink or a peach.” “dramatically” increase sales, the in your mouth and coats your Soft drink companies are among the district’s schools could lose significant tongue and teeth.) most aggressive marketers in the revenue from their soft drink partner. world.8 Advertising budgets of soft Stating that he didn’t want to pressure • Throw the cap away to prevent drink manufacturers are enormous teachers, the administrator suggested ongoing sipping. compared to public service campaigns that the principals “allow students • Read the labels — sweetened promoting the consumption of fruits, virtually unlimited access to the soft drinks are high in sugar. vegetables, healthful diets, and low- drink machines, move them where • Get regular dental cleanings to fat milk. In 1997, Coca-Cola®, they would be accessible to the remove plaque (bacteria) build-up which accounts for 44% of the soft students all day, and permit students on your teeth. drink market in the U.S., spent $277 to purchase and consume vended

18 Northwest Dentistry products throughout the day”, and The place where children spend a 8. Jacobson, M.: Liquid candy, how soft drinks are harming Americans’ health. Website: even “consider allowing students to great portion of their day and where http://www.cspinet.org/sodapop/liquidcandy.html, drink their soft drink products in they are influenced greatly by their sur- 1999. the class”.22 roundings is their school. Schools are 9. Environ Inc., 1988. A 1996 study of 55 high schools in a therefore the most suitable environ- 10. Borrud, L., Wilkinson, D., and Mickle, S.: What we eat: USDA surveys food consumption changes. large metropolitan area found that 11% ment to provide health information to Comm Nutr Inst 1997: 4-5, 1997. of the schools offered soft drinks in children in order to achieve the goal of 11. Albertson,A.,Toblemann,C., Engstrom,A., and Asp, E.: vending machines during school Nutrient intakes of 2 to 10 year old American health promotion programs. It is children: 10 year trends. J Am Diet Assoc 92:1,492-96, 23 hours. As more liberal school policies quite a contradiction to teach princi- 1992. have taken effect recently, this will ples of good nutrition in health educa- 12. Kennedy, E., and Goldberg, J.: What are American children eating? Implications for public policy. Nutr most likely increase. We recently con- tion, then adjourn the class to the Rev 53: 111-126, 1995. ducted a phone survey of Minnesota reality that the children have high 13. Guenther, P.: Beverages in the diets of American school districts and found that the vast accessibility to soft drinks right outside teenagers. J Am Diet Assoc 86: 493-499, 1986. majority do have contracts with soft the classrooms. ■ 14. Harnack, L., Stang, J., and Story, M.: Soft drink con- sumption among US children and adolescents: nutri- drink manufacturers. The annual rev- tional consequences. J Am Diet Assoc 99: 436-441, enue per district is approximately References 1999. $150,000, with some districts even 15. Morbid Mortal Weekly Report, 1994. 1. National Soft Drink Association website, receiving “signing bonuses”. www.nsda.org. 16. Troiano, R., Flegal, K., Kuczmarski, R., Campbell, S., and Johnson, C.: Overweight prevalence and trends for 2. Frazier, W.: Don’t drink soft drinks (and wish you children and adolescents: The National Health Conclusion didn’t). Website: http://[email protected], Examination Surveys. 1963-1991. Arch Ped Adolesc As you may imagine, although the 1999. Med 149: 1,085-91, 1995. 3. Larsen, M.J., and Nyvad, B.: Enamel erosion by some 17. Drewnowski,A.: Sensory preferences for fat and sugar erosion and caries processes are as soft drinks and orange juices relative to their pH, in adolescence and adult . Ann NY Acad Sci 561: different as their histological appear- buffering effect and content of calcium phosphate. 243-250, 1989. Caries Res 33: 81-87, 1999. ance, the two conditions occurring 18. Beauchamp, G.M., and Moran, M.: Dietary experience 4. Massler, M.:Teen-age cariology. Dent Clin No Am 13: and sweet taste preference in human infants. concurrently could be deleterious to 405-23, 1969. Appetite 3: 139-152, 1982. dental hard tissues. As dental profess- 5. Zipkin, J., and McClure, F.J.: Salivary citrate and dental 19. Jamel, H., Sheilman, A., Watt, R., and Cowell, C.: sionals, we need to educate our erosion. J Dent Res 28: 613-626, 1949. Sweet preference, consumption of sweet tea and den- tal caries: studies in urban and rural Iraqi population. patients about the consequences of 6. Thylstrup,A., and Fejerskow, O.: Clinical and patholog- Int Dent J 47: 213-217, 1997. ical features in dental caries. Enamel surface structure. soft drink consumption and provide In Textbook of Clinical Cariology, Second Edition, 20. Vending Times 38: 15, 21, 22, 1998. suggestions to minimize the risk. Thylstrup, A., and Fejerskow, O., eds. Copenhagen: Munksgaard, 1994, pages 112-115. 21. Wall Street Journal, page 1, May 8, 1997. We also need to be active in educating 7. Gedalia, I., Ionat-Benat, D., and Ben-Mosheh. S.: 22. Meskin, L.: Outrageous. JADA 130: 308-310, 1999. school administrators on the negative Tooth enamel softening with a cola type drink and 23. Story, M., Hayes, M., and Kalina, B.: Availability of foods rehardening with hard cheese or stimulated saliva in in high schools: is there a cause for concern? J Am impact soft drinks have on students’ situ. J Oral Rehab 18: 501-506, 1991. teeth. Diet Assoc 96: 123-126, 1996.

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