Abstract
This article examines the relationship between previous fluoridation and socioeconomic status on caries experience, as measured by the dmf index, in 5-yr-old New Zealand children in the city of Dunedin (fluoridated in 1967) and in adjacent non-fluoride communities. The children were subdivided into six socioeconomic status groups (SES 1, professional and managerial-SES 6, unskilled workers), but then for simplicity they were combined to form three groups. A two-way analysis of variance demonstrated that interaction between fluoride history and socioeconomic status was not significant. In all three SES groups, dmf was higher in non-fluoride communities, but the difference was significant only in SES group (5 and 6) (P less than 0.01). Caries experience increased with decreasing socioeconomic status in both fluoride and non-fluoride communities, but this effect was only significant between SES groups (1 and 2) and (3 and 4) in the fluoridated community (P less than 0.05), and between SES groups (3 and 4) and (5 and 6) in non-fluoride communities (P less than 0.01). These results are compared with those of similar studies, and it is concluded that so far, the relationship between previous fluoridation and socioeconomic status on caries experience remains equivocal. A note of caution is sounded regarding the interpretation of such results, and the difficulties faced when comparing studies is discussed.