Changes in the caries prevalence of 11–12-year-old schoolchildren in the North-West of England from 1968 to 1981


V. Clerehugh, Dental Health Unit, Department of Child Dental Health, University Dental Hospital of Manchester, Higher Cambridge St., Manchester M15 6FH, England.


Abstract Since 1968, six caries clinical trials have been conducted in the North-West of England by different examiners using the same diagnostic system, and a steady reduction in caries prevalence in 11–12-yr-old schoolchildren has been recorded. In the present study, five of the examiners revisited some of the schools which participated in their original trials and each examined between 196 and 296 children. The time intervals between the original and repeat examinations were 12, 10, 8, 5 and 3 yr. Percent caries reductions (PCRs) ranged from 19 to 33 for DMFT and from 24 to 35 for DMFS but the PCRs did not relate to the time intervals between examinations. The PCRs were greater on free smooth and approximal surfaces than on fissure surfaces and for the anterior teeth than for the mouth as a whole, suggesting that fluoride may have played a role in the reductions.