A wide range of different methodologies and measurement techniques has been employed in laboratories around the world for the study of de- and remineralization of enamel and dentin in intra-oral systems. These different approaches are summarized and discussed in relation to the nature of the different research questions to be studied by means of the intra-oral model.

The protective role of saliva is demonstrated by the rampant caries seen in human subjects with marked salivary hypofunction, and in desalivated animals. In normal cases, however, the relationship between saliva flow and coronal or root caries experience is doubtful, and to examine the concept that stimulation of saliva might have protective effects against caries, one must look beyond a simple correlation between caries and flow rate. Protective properties of saliva which increase on stimulation include salivary clearance, buffering power, and degree of saturation with respect to tooth mineral. These benefits are maximized when saliva is stimulated after the consumption of fermentable carbohydrates, by reducing the fall in plaque pH leading to demineralization and by increasing the potential for remineralization. Plaque acid production is neutralized, and experimental lesions in enamel are remineralized, when gum is chewed to stimulate saliva after a carbohydrate intake. The pH-raising effects are more easily explained by the buffering action of the stimulated saliva than by clearance of carbohydrates. The remineralization action depends upon the presence of fluoride. These findings suggest that the protective actions of saliva can be mobilized by appropriate salivary stimulation, and that in addition to established procedures such as tooth cleaning and fluoride regimens, eating patterns which lead to saliva stimulation to increase the potential for saliva protection might be included in recommendations for caries prevention. Confirmation of this concept in clinical tests is required.

Intra-oral remineralisation of experimental caries-like lesions in human enamel, as determined by polarised light microscopy and quantitative microradiography, was promoted to a similar extent (% fall in ΔZ, 18.6 and 19.0) by chewing a sorbitol or sorbitol/xylitol (3:l)-sweetened gum for 20 min after each of three meals and two sugary snacks daily. The results suggest that reported differences in the properties of the two sweeteners do not affect their ability to enhance remineralisation due to salivary stimulation.

Numerous desensitizing agents have been utilized in an effort to alleviate the discomfort associated with cervical dentine sensitivity (CDS). Recently several new tubule-occluding and sealant systems have been marketed for treatment. The aim of this study was to compare two desensitizing agents (ALL-BOND 2 and Butler Protect) in a 3-month clinical study. Ten subjects (6F; 4M mean age 45.1 years (SD 8.81) who had provided voluntary written informed consent participated in a single-blind 3-month clinical study. Subjects were evaluated for tactile (Yeaple probe) and air sensitivity (dental air syringe) together with subjective perception of pain (VAS scores) at 0.5 min, 1, 2 and 3 months. There was an overall trend in reduction of CDS over the study period in all group with no significant differences detected between groups. The results suggested that while subjects reported overall reductions in sensitivity levels, this may not necessarily be substantiated when assessed objectively. Furthermore, there appeared to be a strong placebo effect in this study.