Cariogenic potential of presweetened breakfast cereals.

Twelve presweetened breakfast cereals were evaluated for cariogenic potential by in vitro methods. The parameters evaluated were the levels of acid produced by a cariogenic strain of Streptococcus mutans as influenced by each cereal, the percentage of sugar content, and the salivary retention time of glucose after ingestion of each cereal with or witho~¢t milk. Cariogenicity was found to be related to sugar content and most cereals exhibited an increased salivary retention time when consumed without milk. Those cereals with a low cariogenic potential were Cheerios,® Rice Krispies, ® Grape-nuts,® and Cocoa Puffs.® Cereals associated with high cariogenic potential were Cookie Crisp®, Sugar Corn Pops®, Cocoa Krispies, ® Frosted Mini-wheats, ® and Powdered Donutz. ® Thus, two factors should influence the discriminate selection of presweetened breakfast cereals: the quantity of sugar present and the use of the product with or without milk. Each of these flwtors may alter the cariogenicity of breakfast cereals. There has been a growing concern within the dental profession about the cariogenic potential of various foods. Ideally, assessment of food cariogenicity involves several factors which encompass the host, the diet, and. those microorganisms contained in plaque which ferment carbohydrates and produce acids that ultimately cause dental decay through the demineralization process. 1 In addition to the presence of sucrose, other factors such as the frequency or sequence of consumption, salivary retention time, amount of acid formed during fermentation by microbes and the condition under which the food is ingested may affect the cariogenic potential of a food product. 2-6 Because of the increased use of processed snack and convenience foods by consumers, 7 investigations of the cariogenic potential of these foods are necessary to identify products that may be potentially detrimental to teeth. This will enable the clinician and patient to recognize and select foods which are less caries conducive. Several methods have been documented for measuring and comparing the cariogenic potential of foodstuffs. Some of these methods include plaque pH measurements, enamel solubility studies, in vivo plaque and acid formation, dietary monitoring, and animal caries studies. Imfeld et al. s have conducted research on plaque pH measurements through the use of indwelling electrodes during consumption of various foods. Weiss and Bibby9 demonstrated that milk and its casein constituents offered the enamel protection from dissolution in acids. Similarly, Bibby et al. 1° showed that the presence of milk in a fermentable food reduced enamel solubility. Enamel solubility can be reduced by more than 20% when using cows’ milk, regardless of its being raw or pasteurized, whole or skim.9 Further studies on enamel demineralization by Bibby and Mundorff11 indicated that fermentation of snack foods was influenced by flavoring agents and other components. Newbrun et al. 12 compared the dietary habits and dental health of 17 persons with hereditary fructose intolerance, a disorder requiring a lifetime sucroserestricted diet, to those of a control group and concluded that a direct causal relationship exists between sugar ingestion and caries. Berry and Martin4 conducted in vitro acid production and enamel demineralization studies on machine-vended and healthfood snacks to determine their relative caries-promoting ability. Wilson7 measured the effect of readyto-eat cereals on dental caries in 145 adolescent males. Animal studies also have been used to measure cariogenic potential. Stookey13 assessed diet consistency of presweetened cereals in rats. Grenby and 282 CARIOGENIC POTENTIAUPRESWEETENED CEREALS: Minton and Berry Bull1. studied the effects of breakfast cereals on dental caries in rats as well as caries control using a calcium glycerophosphate additive. Egelberg is determined the importance of diet consistency in bacterial plaque formation and gingivitis in dogs by studying the effects of dietary frequency and oral bypass. Interest in determining the cariogenic potential of sucrose-containing foods not only has been stimulated by the increased consumption of processed foods containing sucrose, 7 but also by the advertising of these foods. Presweetened cereals were chosen for this study because presweetened cereals often are eaten as between meal snacks without milk. 16 Also, children, the primary consumers of presweetened cereals, are the main target of advertising of those cereals having a higher sugar content. 16-~s If presweetened cereals are consumed as snacks without milk then the protective effect of casein in milk is absent. Additionally, cereals consumed dry are more likely to stick to teeth, thus increasing the retention of fermentable carbohydrates in the mouth, g The present study included 3 methods to measure the in vitro ability of a cariogenic strain of Streptococcus mutans to produce acid from fermentable carbohydrates found in each cereal and a method to determine salivary retention time of glucose after the consumption of each cereal either with or without milk. Methods and Materials Twelve presweetened breakfast cereals were chosen for evaluation of their cariogenic potential: Cookie Crisp, a Cocoa Krispies, b Fruit Loops, b Sugar Corn Pops, b Frosted Mini-wheats, b Rice Krispies, b Sugar Frosted Flakes, b Cocoa Puffs, c Powdered Donutz, c Cheerios, ¢ Cap’n Crunch, a and Grape-nuts. e These cereals were selected by a preadolescent consumer and purchased from a local grocery store. All cereals are available at most supermarkets since they are advertised and distributed nationally. Prior to analysis each cereal was crushed with a mortar and pestle to an equivalent consistency, and then sterilized using ethylene oxide gas to avoid the possibility of contamination from microorganisms within the cereal or from the environment. The experimental design incorporated several test or control conditions for each cereal to examine acid production and demineralization. Each tube contained a basal broth medium which included tryptiRalston Purina Co: St Louis, MO. Kellogg’s: Battle Creek, MI. General Mills, Inc: Minneapolis, MN. Quaker Oats Co: Chicago, IL. Post/General Foods Corp: White Plains, NY. case but no added carbohydrates or buffers. ~9 The test or control conditions included 10 ml of basal medium, S. mutans strain 6715 cells suspended in a solution of sterile phosphate buffer (0.06 M, pH 6.8), 10 mg of hydroxyapatite (HA), and 0.5 g cereal, either singly or in combination. Each test mixture was placed in an anaerobic chamber containing an atmosphere of 85% nitrogen, 10% hydrogen, and 5% carbon dioxide and allowed to incubate for 24 hr at 35°C. Three methods were used to estimate acid production of S. mutans -terminal pH, total titratable acidity, and calcium ion release through demineralization of HA, the main inorganic component of enamel. Change in Terminal pH After incubation, a pH meter f was used to obtain the level of acidity of each test or control mixture. By subtracting the final pH value from the initial, the change in pH due to the acids formed by S. mutans while metabolizing the components of each cereal was evaluated. Total Titratable Acidity The quantity of 0.001 M sodium hydroxide necessary to back titrate each test or control condition to the starting pH of the uninoculated control was determined using a pH meter and a buret filled with titrant. Calcium Ion Release Demineralization of HA was monitored by measuring the release of calcium ion. A 20-~1 aliquot was removed from each test or control mixture and added to a working solution of calcium reagent. 2° The calcium level in each sample then was estimated using a fluorometer.g The relative intensity of fluorescence of each tube was compared to a standard curve of known calcein levels. Oral Retention Time Salivary retention of the reducing sugars of each cereal used in the study was analyzed by a glucose oxidase h method. Each of 6 volunteers was provided 6, 1-ounce servings of 2 cereals which were ingested without milk on 3 different days. Concentrations of salivary glucose in subjects were tested before ingestion of test cereals, immediately after, and at 10-min intervals during a 30-min period. An identical analysis also was performed on the same cereals moistened with milk. Model 125 -Corning Instruments: Medfield, MA. Model J4-8960 Aminco Bowman Spectrophotofluorometer -American Instrument Co: Silver Spring, MD. Ames Co, Miles Laboratories, Inc: Elkhart, IN. PEDIATRIC DENTISTRY: December 1985/Vol. 7 No. 4 283 Statistical Analysis The data were evaluated for correlation between the sugar content of each cereal and acid production measured by 3 met:hods. The Pearson’s product-moment correlation coefficient (r) 21 wag calculated 22 for each method.