Objective & Design: To compare cross-sectional caries prevalence data of 11.5 year old children over a 13 year period (1989-2001) and to evaluate the maximum effect of the applied preventive programme (sealants to 1st molars and 6-year health education) on DMFT values during the last five years. Participants: Using the records of a Public Health Centre (PHC) in NE Greece, a number (153-250) of children aged 11.5-years were selected from each calendar year, constituting 11 study groups (totalling 2,217 children), stratified by area of residency. Method: Annual oral health education sessions provided in 1990, a year after the PHC was established. Light-cured fissure sealants were systematically mass introduced in 1996. The same dentist completed all DMFT records in the dental clinic during the children’s routine visits. DMFT was analysed using two Poisson and two Binomial models for both data from all years, and for the last five years. The models had as factors: “Time” (year of examination of the study group), “Residency” (semi urban, rural lowland, rural highland), number of “Sealed 1st molars” and “Sealed posterior teeth”. Results: All the factors were highly statistically significant (p<0.001). Dental health was found to be good (DMFT=0), improving progressively year by year (range 12-50%). The mean DMFT decreased steadily from 4.5 (in 1989) to 1.81 (in 2001). The Significant Caries index was almost halved (from 8.08 to 4.23). Conclusion: An important improvement in the caries status of 11.5 year-olds since 1989 has been demonstrated, irrespective of the residency. The systematic application of fissure sealants to all 1st molars, parallel to the cumulative effect of the 6-year health education programme per child, played a significant role in reducing disparities in disease prevalence, despite the difficulty of improving rates of decline when the caries levels are relatively low. Key words: Caries prevalence, children, fissure sealants, poisson distribution public health center