AbstractTen‐to 13‐year‐old children were examined annually for three years to determine the caries activity in the proximal and occlusal surfaces of first permanent molars. Almost every tooth with an unsound (carious or filled) proximal surface also had an unsound occlusal surface. Caries scores in proximal surfaces remained relatively constant and low. The percentage of teeth with occlusal caries or fillings increased throughout the study, even though the teeth had been erupted for seven to ten years by the end of the study. Within the age range studied, the time that teeth were in the mouth had little effect on the vulnerability of occlusal surfaces to caries a