Protocols to study dental caries in vitro: pH cycling models

As laboratory models are bridges to in vivo caries studies, they must mirror clinical conditions, where demineralization and remineralization alternate constantly (i.e., pH cycling) and are only interrupted during the very short period of application of investigational products, such as toothpaste or mouth rinse. In view of this, models have been developed, based on pH cycling, to study the anticaries or caries remineralizing effects of substances. The pH cycling models have long been accepted and utilized by the scientific community and the toothpaste industry as an appropriate alternative to animal caries testing, particularly for ionic fluoride-based dentifrices. Several pH cycling models have been developed and described in the literature over the years. However, in this chapter, we crudely categorize them into two types: According to what the investigational product is tailored to achieve, i.e., prevention of caries development (net demineralization) or remineralization of early caries (net remineralization). Thus the models are termed “demineralization” or “remineralization” models and are described in details here together with their disadvantages and applications.