Longitudinal radiographic analysis of carious lesion progression. Information on the rate at which carious lesions progress through the enamel of human teeth in an adult population was obtained from dental radiographs taken at 3-yr intervals, over a 10-yr period on 602 men. Clinical measures of calculus deposition, plaque accumulation, gingival inflammation, tooth mobility, periodontal pocket depth, and gingival recession were studied to find predictors that might be of value to the clinician for determining how frequently radiographs should be taken. We estimate that 50% of the enamel lesions on mesial and distal surfaces, if left untreated, would not progress into the dentin until 73 months had elapsed after the lesion was initiated. Significant differences in the progression rate were associated with the arch and tooth type. Patient age, number of decayed or filled surfaces, degree of gingival inflammation, amount of recession, and plaque accumulation were positively associated with more rapid caries progression, while greater numbers of teeth present were predictive of slower disease progression. Published in Community dentistry and oral epidemiology (1988)