The impact of education on the probability of receiving periodontal treatment. Causal effects measured by using the introduction of a school reform in Norway

•Education has a causal effect on the probability of receiving periodontal treatment.•Education is important, even with a strong public involvement in dental care.•The introduction of a school reform was used as the instrumental variable.

The aim of the present study was to estimate the causal effect of education on the probability of receiving periodontal treatment in the adult Norwegian population. In Norway, a substantial part of the cost of periodontal treatment is subsidized by the National Insurance Scheme. In that case, one might expect that the influence of individual resources, such as education, on receiving treatment would be reduced or eliminated. Causal effects were estimated by using data on a school reform in Norway. During the period 1960-1972, all municipalities in Norway were required to increase the number of compulsory years of schooling from seven to nine years. The education reform was used to create exogenous variation in the education variable. The education data were combined with large sets of data from the Norwegian Health Economics Administration and Statistics Norway. Since municipalities implemented the reform at different times, we have both cross-sectional and time-series variation in the reform instrument. Thus we were able to estimate the effect of education on the probability of receiving periodontal treatment by controlling for municipality fixed effects and trend variables. The probability of receiving periodontal treatment increased by 1.4-1.8 percentage points per additional year of schooling. This is a reasonably strong effect, which indicates that policies to increase the level of education in the population can be an effective tool to improve oral health, including periodontal health.