Tooth Decay
How Cavities Occur
On their own, none of the three factors shown in the diagram below will cause tooth decay. However, if all three are present at the same time, the cariogenic (cavity- producing) bacteria break down the fermentable carbohydrates to produce acid which immediately attacks susceptible tooth enamel.
The Factors That Add Up To
Tooth Decay
| Carbohydrates such as cooked starch and glucose can be rapidly fermented to form acids that are cariogenic. The "arch criminal of cavities" is sucrose, an easily fermentable carbohydrate that forms sticky macromolecules which make plaque adhere tightly to teeth and prevent saliva from rinsing away acids. |  |
Mutans streptococci are the most cariogenic of all oral bacteria with properties that are particularly insidious in promoting tooth decay: - they colonize and form plaque that tightly adheres to teeth - they produce large amounts of acid which dissolves enamel - they multiply in acidic conditions found in the mouth |
The susceptibility of an individual to cavities is influenced by a number of factors including diet, eating patterns, resistance of the tooth surface to plaque and the salivary flow rate.
The composition of diet, personal habits (brushing teeth, flossing) and outside factors such as regular exposure to fluorides can greatly influence the development of cavities. The frequency and timing of consuming foods containing carbohydrates , especially the habits of snacking and ending meals with a sweet (sugar-filled) dessert, can also significantly contribute to the risk of tooth decay. In order to reduce the exposure to sucrose, particularly high-risk foods such as confectionery, sugar substitutes are being used to manufacture confectionery and other sweetened products which are "safe for teeth". Xylitol is one of these alternatives and is, to date, the only one which is clinically proven to be beneficial to oral health with regular use.
How Xylitol Fights Tooth Decay
Clinical studies conducted in populations with both high and low cavity incidence show that supplementing a normal diet with regular consumption of xylitol (e.g. sweetened chewing gum > 2 times/day) is of clear benefit to the teeth.
When carbohydrate or sugars are consumed acid is produced in the mouth and the pH drops rapidly below pH 5.7, causing demineralization of tooth enamel and potential cavities. Since xylitol is a five-carbon polyol, oral bacteria do not metabolize it and therefore no acid is produced. When xylitol products are used the pH balance in the oral cavity is quickly returned to a safe level above pH 5.7, minimizing the erosion of enamel and enhancing the remineralization process. The pleasant sweetness also stimulates saliva flow, which helps to rinse away excess sugar residues and neutralize any acids that have been formed.
When xylitol is consumed habitually for several months, the mutans streptococci are shed from plaque to the saliva. Although high numbers may still be found in saliva, they are less virulent and do not adhere as tightly to the teeth, and this means acid attack is not occurring at the tooth surface.
In conclusion, xylitol is both non-cariogenic in that it does not contribute to caries formation and is cariostatic because it prevents or reduces the incidence of new caries. Xylitol actually reduces the amount of plaque and the number of mutans streptococci in plaque. No other sugar substitute has been shown to function in this way.
