Dental caries, a progressive bacterial damage to teeth, is one of the most common diseases that affects 95% of the population and is still a major cause of tooth loss. Unfortunately, there is currently no highly sensitive and specific clinical means for its detection in its early stages. The accurate detection of early caries in enamel would be of significant clinical value. Since, it is possible to reverse the process of decay therapeutically at this stage, i.e. operative intervention might be avoided. Caries diagnosis continues to be a challenging task for the dental practitioners. Researchers are developing tools that are sensitive and specific enough for the current presentation of caries. These tools are being tested both in vitro and in vivo however, no single method will allow detection of caries on all tooth surfaces. Therefore, the purpose of the present review was to evaluate different caries diagnostic methods.1 Many dental schools in the U.S. are adopting a new system for caries diagnosis?the International Caries Detection & Assessment System (ICDAS). We will introduce the ICDAS system and correlate it to the standard ADA recognized U.S. system of caries diagnosis. We will also discuss the importance of caries diagnosis in clinical practice today and also briefly touch on the issue of the ethics of caries diagnosis. In this educational activity, we will review technologies to assist the dentist with the diagnosis of dental caries; however, it is extremely important to realize, especially for the young dental professional, that the diagnosis of a carious lesion is only one aspect of the entire management phase for dental caries. In fact, there are many aspects of managing the caries process be?sides diagnosis.2,3 Caries detection is a basic task that all oral healthcare professionals are taught in school. In principle it is very sim-ple detect mineral loss in teeth visually, radiographically or by some other adjunctive method. There can be many issues that affect this task, including training, experience, and sub-jectivity of the observer; operating conditions and reliability of the diagnostic equipment. These factors and others can all act in concert and often, the end result is that this ?simple? task becomes complex. A critical factor to consider is that most of the research on caries detection has focused on oc?clusal and smooth surface caries. There are two reasons for this first of all, from a population stand point, more new carious lesions are occlusal lesions today than in the past 4,5 and, secondly, many studies rely on screening examinations without intraoral radiographic capability 6,7