Initial caries attack and average progression rates in 12-year-old Isle of Wight children

Initial caries attack and progression rates of posterior approximal carious lesions were assessed based on 12-year-old school children residing on the Isle of Wight. Bitewing radiographs of a sub-sample of 165 subjects were randomly selected from the control group of a dentifrice clinical trial which took place between 1984 and 1987. Of the approximal surfaces that were caries-free at the first examination 71 per cent of the same surfaces remained caries-free after three years, an overall initial caries attack rate averaging 10.7 per cent per annum. Of the mesial surfaces of first permanent molars, 455 were initially caries-free, 67 per cent of which remained so after a three year period. The attack rate of this specified surface was 12.4 per cent per annum. The majority of surfaces that were caries-free at the start of the investigation would therefore be expected to remain so at least three years later. Caries progression appeared to be a slow process with only 12 per cent of initially carious outer enamel surface lesions penetrating into dentine after one year. After two years this had increased to 46 per cent and after three years, to 62 per cent. For a similarly defined group of individuals it would appear likely that the majority of early enamel lesions would not reach dentine within two years. For a substantial number of subjects this would extend to at least three years.