Studies of dental fear and oral disease suggest that conditioning processes are important in the acquisition of dental fear. At this time, however, definitive conclusions are premature as all research on the etiology of dental fear has been retrospective in design, with most confined to analogue or clinic samples. This study redressed these limitations by prospectively investigating the relationship between oral health (i.e. caries experience) at age 5 and 15 yr and the report of dental fear at age 18 in a large, unselected birth cohort. Caries experience at age 5 was not related to the development of dental fear in late adolescence. In contrast, caries experience at age 15 was significantly, and specifically, related to the report of dental fear at age 18. A ratio of caries severity at age 15, indicating the extent of multi-surface involvement, was inversely related to dental fear at age 18. This intriguing finding suggests that relatively brief dental treatment occasioned by low levels of dental disease may result in the incubation of dental fear in some individuals and that longer episodes of treatment may facilitate fear habituation. Theoretical and practical implications of these findings are discussed.