Social gradients and cumulative effects of income and education on dental health in the Fourth German Oral Health Study

Objective: To consider differential effects of income and education on oral health for each indicator separately and in combination. Finally the combined effects of the lowest income level and the lowest level of education were examined. Methods: Data were drawn from the Fourth German Oral Health Study. They were collected using proportional random sampling in order to obtain information also for less densely populated regions. The subjects included in the study were between 35 and 44 years of age (n = 925). It included a clinical dental examination and a sociological survey. Social differentiation was depicted by education and income (divided into categories), oral health was measured using the DMFT-index. Results: Social gradients emerged for both indicators of social differentiation. The effects derived from single analyses were somewhat higher than those obtained by simultaneous estimations. The odds ratio of the lowest as compared with the highest income category was OR = 3.74 and OR = 2.34 in the analysis with both indicators. For education the respective effects were OR = 3.75 and OR = 2.95. The cumulative effect of the lowest income and the lowest educational level combined was OR = 6.06. Conclusion: Education and income are shaping social inequalities in oral health independently from each other, and they are only moderately correlated. They refer to different dimensions of disadvantage thus making preventive measures more complicated.