Abstract
In his conference presentation, Proskin discussed the concepts of validity and reliability of caries models, and reviewed the Proskin-Chilton-Kingman procedure for using models to assess the clinical efficacy of a therapeutic agent. He presented a generally positive view of caries models as substitutes for clinical studies under certain conditions. In this reaction paper I propose a stronger definition of validity, and discuss conceptual and practical requirements that caries models must meet before they can be used in place of clinical studies. Meeting these requirements may depend on obtaining new clinical data; making greater use of existing clinical data; and a willingness to adopt a limited set of standardized models for demonstrating clinical efficacy.