Sir, we agree with Davies and Bridgman (Br Dent J 2011; 210: 59–61) regarding methods of improving oral health among children. Indeed, we once trusted in the virtuous circle of prevention: education, knowledge, awareness, long-term effectiveness. We must now acknowledge that education alone cannot guarantee an effective prevention and may increase health inequalities; but there is something worse. Knowledge is a necessary but not sufficient condition for awareness, which is the perception and the cognitive reaction to an event, and parents' knowledge does not necessarily imply their awareness. For example, despite expensive and nationwide campaigns specifically directed to adults from low socio-economic strata in the USA and Australia, many parents do not seat their children in the rear seats of passenger vehicles, smoke at home and are not aware of their children's nutrition. The unpleasant aspect of these examples lies in the dichotomy between parents' knowledge and awareness toward their children's health.

This paradoxical effect, called the Inverse Care Law ('individuals and groups who are in minor need of an intervention benefit more from it than those who are in major need'), was enunciated by Julian Hart in 1971,1 is now corroborated by many examples, and applies also at community level, since public water fluoridation in Brazil is more common in wealthy than in poor municipalities.2 Co-morbidity and fatalism amongst low-income strata are the major factors associated with the Inverse Care Law. Underprivileged individuals and families frequently suffer many conditions simultaneously, which compromise health and social problems; the most common of them is psychological distress. Early childhood caries is associated with psychological distress3 and parents with such co-morbidity do not necessarily concentrate their attention on caries.4 Fatalism is the view that we are powerless to do anything other than what we actually do. Fatalistic individuals believe that there is nothing they can do to cure or prevent any condition that they are fated to develop, regardless of their level of health literacy. Among low-income communities, such as the Chinese and the African-American communities in the UK and USA, fatalism is associated with poor oral health. Fatalism and co-morbidity may act synergistically, leading to aboulia and the unlikelihood to adopt any health (including oral health)-oriented behaviour.

How can we get rid of the Inverse Care Law? The approach proposed by the Viennese psychiatrist Arthur Adler was that only healthy individuals, with a complete state of physical, mental and social wellbeing, may change and improve their lifestyle. Therefore, the prerequisites for health of the Ottawa Charter for Health Promotion (such as income, stable eco-system, education, sustainable resources, social justice) evocated by Davies and Bridgman are the fundamentals to achieve the goal of oral health for all without inequalities.