Experimental Models of the Caries Process

Because direct manipulation of the caries process in human subjects is impossible for ethical reasons, a number of techniques have been developed that provide insights without risking clinical damage to the teeth of experimental subjects. Much of the earlier work relied on measurements of the change in plaque pH that followed a single consumption episode of a food or drink containing a source of fermentable carbohydrate. This approach provides an indication of the potential cariogenic challenge of these exposures and addresses the fundamental question of whether pH falls to a level that is expected to give rise to demineralization of the tooth enamel. Plaque pH measurements have thus been used to assess whether a food or drink may be considered safe for teeth. But this technique does not provide any information on the influence of the repair processes that follow exposure to a demineralizing challenge.

Approaches that provide an insight into the balance of demineralization and remineralization episodes over a period of time with naturalistic eating and drinking circumstances have now become more commonly used. These involve placing an enamel sample within a subject's dentition and carefully assessing any changes in the surface of this sample over a period of time. Particular cariogenic challenges can be applied, but, because they are continued for only a limited period of time, the subject's own teeth will not be appreciably affected. In many cases, the enamel sample is not cleaned with fluoride toothpaste, whereas the subject's own teeth are so protected (the additional enamel sample being removed while the teeth are brushed).

These models have provided useful information not only on the relative cariogenic potential of different foods and drinks but also on the protective effects of fluoride toothpaste (even though it may not be applied directly to the enamel sample) and on the influence of stagnation sites on caries risk with different dietary practices. Useful indications of answers to important public-health questions are beginning to emerge from this kind of research, such as the number of exposures to fermentable carbohydrate that can be tolerated without appreciable risk to the teeth, and the influence of fluoride toothpaste use on this number.

Breaking Bulimia

Breaking Bulimia

We have all been there: turning to the refrigerator if feeling lonely or bored or indulging in seconds or thirds if strained. But if you suffer from bulimia, the from time to time urge to overeat is more like an obsession.

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