One of the major problems in studying dental diseases and its factors is the development of a suitable, practicable method for recording and classifying the occurrence and severity of the disease. Lord Kelvin once stated that, "until you can count it, weigh it, or express it in Quantitative fashion, you have scarcely begun to think about the problem in a scientific fashion."Dental index can be considered as the main tool of epidemiological studies in dental diseases, to determine the incidence, prevalence and severity of the diseases based on which preventive programmes are adopted for their control and prevention. This manuscript is an attempt to make an update on indices used in oral diseases and will be useful to the professionals who are involved in research projects.