Different indices to identify dental diseases have been developed. For population-based studies, it is imperative to use simple and reliable indices, but most importantly, clinical examiners should reach an agreement, in order to increase inter-observer reliability and obtain reliable data. The objective of this study was to describe the calibration process of the Dental Aesthetic Index, Community Periodontal Index, Simplified Oral Hygiene Index and International Caries Detection and Assessment System ICDAS II by two academics from the Public Health Department of Dentistry. All calibrations started with the individual reading of the official documents of each index and, when possible, were followed by a lecture, in-vitro or ex-vivo training and concluded with an in-vivo training. A high inter-observer reliability was obtained between the two academics in all indices.