SUMMARY

The DMFT (S) index, created at a time when caries was thought to be an irreversible condition of the tooth structures, proves now to be insufficiently informative under the present situation. The non-operative preventive therapeutic approach is highly regarded now, which is an approach requiring additional information on the reversible carious pathology so that an adequate treatment could be applied. The epidemiological examination of a 1000 children aged 6- 15 has been conducted in Sofia and Rousse – two big Bulgarian cities in which no public prophylactic programme has been carried out. On the basis of predetermined diagnostic criteria for the determination of the reversible phases in the development of the dental caries and by accepting an early diagnostic thershold, an IR reversibility index was created. This index is very helpful in supplementing the information obtained by means of the DMFT and DMFS indexes, allowing us to determine the correlation between the reversible and irreversible lesions within the DMF index and making possible adequate therapeutic decision-making. The IR reversibility index is there for the sake of preventive approach in modern cariesology and can successfully be used in epidemiological studies. Epidemiological studies are conducted in the world all the time, aimed at monitoring the level of development of the caries distribution (1, 3, 4, 5, 6, 20). Hence the possibility for comparison between the different countries, geographic regions, groups and populations. The studies reflect the medical therapy conducted, the need for therapy as well as the volume of the social and group prophylactic measures taken (2, 8, 9, 11, 14, 15). In order that comparisons could be reliable, a unification of the indexes applied as well as a unification of the diagnostic bands and criteria use