The international trend in caries management is to move away from the surgical model (to excise and replace diseased tooth tissue) towards a preventive approach aiming to control the initiation and progression of the disease process over a person’s lifetime. Therefore, a major challenge for the clinician is to detect lesions at an early stage, before surgical intervention is needed. The epidemiological examiner has to capture information about need of preventive treatment rather than just the number of fillings required; and the clinical researcher has to assess the effectiveness of products and strategies aiming to control the caries process and prevent disease progression to advanced stage disease that needs restoration. Another major challenge is to detect caries activity at the lesion stage. Unfortunately, despite claims that some new clinical criteria systems are reliable, we contend that additional studies are needed before clinicians in general practice can reliably assess caries activity. In view of the range of dental caries and the various stages of caries that can be detected and differentiated from one another (figure 1), clarity is needed in discussion and reporting of these stages of decay to ensure that patient care, dental-care policies and evidence-based practices are in agreement. Some controversy exists as to the effect of the different diagnostic cutoff points and to the feasibility of epidemiological data collection that includes lesions in the enamel, although results of studies and practices in some countries show that both are desirable. Seemingly trivial changes in diagnostic criteria can produce sizeable differences in the amount of disease recorded. Figure 4 shows the caries process as recorded by classic epidemiology and the inappropriateness of using the term caries free
when reporting the results of surveys that only record dentine lesions seen clinically, in view of the proportion judged caries free who could have undetected disease. Rather than claim such groups are free of disease, many authorities are now using terms such as no obvious decay.