Dental caries is a complex disease affecting the teeth, which is mainly caused by imbalance between demineralization and remineralization process around the tooth surface. It is a major cause of tooth loss and pain around the world. Today it is one of the most common diseases of world which if left untreated lead to infection, pain and tooth loss. Therefore there is need for early assessment of dental caries to lower its prevalence and to assess efficiency in the provision of preventive and therapeutic dental services, to know the selective use of dental caries preventives and targeting of services toward persons at greatest risk. For early assessment of dental caries, indices can be used to know its prevalence and the population which is at higher risk. There are some limitations in the previously developed dental caries index regarding the quantification and severity of diseases. To solve these problems later new indices are developed like ICDAS, PUFA, CAST index. Dental caries index helpful in detection of oral diseases on large scale in field survey. Provide data regarding prevalence of a particular condition occurring within a given population and use of this data for the implementation of the dental caries prevention program.