Accumulation of Fermentable Sugars and Metabolic Acids in Food Particles that Become Entrapped on the Dentition

S. Kashket, J. Zhang, J. Van Houte

Abstract

Earlier studies (Kashket et al., 1991) showed that particles of high-starch snack foods remained longer on the teeth than those of high-sucrose, low-starch foods. The question arose whether the prolonged presence of food particles enhances cariogenicity. A study was undertaken to measure sugars, starches, and metabolic acids in retained food particles. Subjects consumed portions of different foods, and particles were removed from all bicuspids and first molars at defined times after swallowing. Dry weights, sugars, and short-chain carboxylic acids were determined. High-sucrose foods were cleared rapidly from the teeth, while high-starch foods were retained for up to 20 min. Sucrose, glucose, and fructose persisted in the retained particles. Particles of high-starch foods accumulated maltose and maltotriose, presumably from the breakdown of starch by salivary amylase. At maximum, maltose plus maltotriose constituted 94% of total sugars in particles of potato chips; corresponding values in doughnuts, peanut butter cookies, and salted crackers were 43, 51, and 61%, respectively. Total fermentable sugars in the particles of high-starch foods were similar to those for the high-sucrose confectionery products. Carboxylic acids accumulated within the particles, presumably due to the fermentation of the sugars by entrapped salivary micro-organisms. At maximum (5 to 7 min), acetic, formic, lactic, and propionic acids rose 17-, 30-, 15-, and 1.3-fold, respectively, in dough-nuts, and to smaller degrees in potato chips, salted crackers, and chocolate-caramel-peanut bars. In summary, the study demonstrated the persistence of sugars, the progressive accumulation of starch breakdown products, and the fermentation of the accumulated sugars in retained food particles. The findings support the view that high-starch foods contribute to the development of caries lesions.

 Original Paper

Caries Res 1999;33:123–129

Human Salivary Sugar Clearance after Sugar Rinses and Intake of Foodstuffs

G.A. Luke H. Gough J.A. Beeley D.A.M. Geddes
Oral Sciences, University of Glasgow Dental Hospital and School, Glasgow, Scotland, UK

Abstract

The aetiology of dental caries is in part related to the re- tention time of dietary carbohydrates in the oral cavity and their subsequent metabolism by the oral bacteria. Salivary clearance of fermentable carbohydrates from three different foodstuffs was examined in 5 subjects and analyses performed by high-performance anion-ex- change chromatography with pulsed amperometric de- tection. The clearance of glucose, fructose, sucrose, mal- tose and sorbitol rinses was studied as well as that of chocolate bars, white bread and bananas. Of the sugar rinses studied, sucrose was removed from saliva most rapidly whilst appreciable levels of sorbitol remained even after 1 h. Clearance of residual carbohydrates from bananas and chocolate bars seemed marginally faster than in the case of bread, but sucrose levels still tended to fall more quickly than other carbohydrates studied. Surprisingly, carbohydrate residues from the three foods studied were still present in the mouth even 1 h after in- gestion, which is longer than has hitherto been reported.

Dental caries is initiated by the consumption of fer- mentable carbohydrates which are converted into organic acids by bacteria in dental plaque. The rise in acidity can cause demineralisation. Since cariogenic effects are, in part, related to the retention time of carbohydrates in the mouth as a result of their acidogenicity, the role of saliva in oral carbohydrate clearance is of primary interest. The salivary clearance of sugars is influenced by the properties of the foodstuff [Lundqvist, 1952], the amount of ingested carbo- hydrate [Goulet and Brudevold, 1984], the sampling site in the mouth [Britse and Lagerlöf, 1987; Strong et al., 1987] and physiological factors such as salivary flow rate and the volume of saliva in the mouth before and after swallowing [Dawes, 1983; Lagerlöf et al., 1987].

Analytical methods for the determination of carbohy- drates in foods and biological fluids include enzymatic methods [Hase et al., 1987; Lindfors and Lagerlöf, 1988; Weatherell et al., 1989] and chromatographic techniques in- cluding paper chromatography and thin layer chromatogra- phy [Carlson, 1968; Anumula and Spiro, 1983]. High per- formance ion-exchange chromatography combined with pulsed amperometric detection (HPIEC-PAD) provides the most selective and sensitive method currently available for analysing complex samples containing carbohydrate-con- taining samples such as saliva [Gough et al., 1996]. The procedure can be used on small sample volumes (50 μl) and can simultaneously determine the level of more than one carbohydrate in any given sample. Using this technique we have examined the clearance from saliva of the carbohy- drates glucose, fructose, sucrose, maltose and sorbitol after a mouth rinse and the clearance of relevant sugars after eat- ing carbohydrate containing-foods.

J.A. Beeley
Oral Sciences, University of Glasgow Dental Hospital and School 378 Sauchiehall Street
Glasgow G2 3JZ, Scotland (UK)
Tel. +44 0141 211 9755, Fax +44 0141 353 1593

The Relationship between Plaque pH and Glycemic Index of Various Breads

P. Lingström, H. Liljeberg, I. Björck and D. Birkhed

Abstract

Plaque pH was studied during 60 min in situ in 10 sub- jects after eating various breads. The pH response was then compared to glycemic index (GI; calculated from the incremental blood glucose area) obtained from our earlier investigations. The following four products were tested: (1) barley kernel bread (BKB), (2) BKB, sourdough-fermented (BKBS), (3) white wheat bread (WWB), and (4) syrup-sweetened wheat-rye bread (SWRB). BKB was also tested with more intensive chew- ing and SWRB with the addition of fat. A 5% sucrose so- lution served as a control. The pH drops with all the breads were considerably smaller than with the sucrose solution during the first 15 min. From 30 min and on- wards the breads gave similar, or even lower (SWRB) pH than sucrose. There was a great difference in pH re- sponse among the four breads, with the most pro- nounced pH fall for SWRB, followed by WWB (based on the AUC values). Intensive chewing of BKB increased, while the addition of fat to SWRB reduced the pH fall, in both cases by about 0.2 pH units. A high correlation (r = 0.94) between plaque pH and GI was found, i.e. the more pronounced the pH drop in plaque, the higher the GI in blood. Therefore, both from a cariogenic and from a metabolic point of view, breads with a low GI should be recommended.