Objective: To test the hypothesis that the 1990–91 social and economic policy changes in New Zealand were associated with a subsequent increase in socio-economic and ethnic inequalities in the dental caries experience of five-year-old children.

Method: Dental caries data from the School Dental Service treating the greater Wellington area were analysed for the period 1995–2000. Multivariate models were developed for deciduous caries prevalence (logistic regression) and severity (negative binomial regression).

Results: In the years 1995, 1996, 1997, 1998, 1999 and 2000, complete data were available for 2,627, 3,335, 4,404, 4,155, 3,154 and 2,804 children, respectively. Ethnic and socio-economic differences in caries prevalence and severity were substantial and persistent during the observation period. Where caries severity was concerned, there was a significant interaction between time and Maori ethnicity, indicating that (on average) the oral health of Maori children deteriorated in comparison to their European counterparts.

Conclusions: The early-1990s social and economic policy changes were associated with an apparent widening of ethnic inequalities in caries severity among five-year-old children.

Implications: Economic rationalism appears to have oral health disadvantages for non-European children. Before implementation of proposed major social and economic policy changes, policymakers should consider their health implications.