Changes in caries diagnostic criteria over time related to the insertion of fillings. A comparative study.

The attitude toward the need for restorative treatment of carious approximal tooth surfaces changed gradually during the 1970s. The depth of the carious lesions and an assessment of their progression rate was recommended to be the basis for decisions of whether preventive measures or restorative therapy should be applied. The aim of this study was to examine whether this view on caries therapy had influenced the treatment of posterior approximal surfaces and the choice of caries diagnostic criteria in studies on changes in caries prevalence over time. The material comprised posterior bitewing radiographs and records from the annual dental care of two groups of teenagers, born in 1964 an 1971, respectively. By means of an index system every approximal surface from the distal surface of the first premolars to the mesial surface of the second molars was given a caries diagnostic score on the basis of the depth of the lesions. The fillings inserted during the same treatment period as the radiographs had been taken were then grouped on the basis of the scores. At 13 years of age the percentage of fillings inserted in teeth with carious lesions extending into the outer and those extending into the inner half of the enamel was significantly higher in children born in 1964 than those born in 1971. This was also the case with fillings inserted at 16 years of age in teeth with lesions extending into the inner half of the enamel. On the basis of these results it was concluded that comparisons between the two groups with regard to approximal caries prevalence has to be based on criteria that cover both fillings and initial and frank carious lesions. This seems to have a general bearing on comparisons between groups of the same age but with different years of birth.