Sir, as lecturers in the sociology of oral health we endeavour to instil critical awareness about oral health inequalities among our dental students. Published data sources help us to demonstrate the social patterning of oral health and in turn strengthen our claims as to the social determinants of oral health and the persistence of oral health inequalities.

Previous child dental health surveys recorded child oral health according to a variety of social variables, including household composition and socio-economic status (NS-SEC).1 However, the 2013 Child Dental Health Survey incorporated a change in the reporting of area classifications to include ONS 2011 output area classification (OAC). These OACs are based on the grouping together of 'similar geographic areas according to key characteristics common to the population in that grouping'.2 The role of the OAC is 'intended to be illustrative of the characteristics of areas in terms of their demographic structure, household composition, housing, socio-economic characteristics and employment patterns'.3 As a result, according to the 2013 survey, 22% of 'hard pressed living' children at the age of five in England, Wales and Northern Ireland have severe or extensive dental decay, compared with 18% of 'constrained city dwellers' children aged five, 9% 'suburbanites' and 9% 'urbanites' children aged five.4 While a glossary of each of these groups are included in the technical report2 we query the empirical utility of these classifications.

The ONS admit that these OAC groups, such as 'constrained urban dweller' and 'urbanites' represent 'the most generic description of the population of the UK'.3 Nevertheless, how we define and measure health is a political act, influencing public opinion of health and health policy more generally.5 By using the OAC classifications the distribution of child oral health is recorded not according to social class but rather to these 'fuzzy' descriptive classifications. This change in reporting makes it difficult to compare 2013 data with previous surveys, which relied on the established socio-economic status classification, having a negative impact on our capacity to assess oral health trends over time and across social groups. As a result, the 'clustering of disadvantage' associated with poor oral health becomes obscured, reducing in turn our ability to monitor the 'health gaps'5 that exist in society. The lack of accurate social/epidemiological data will also detract from recent efforts within the dental profession in the UK on how the profession can work to reduce health inequalities and contribute to a more equal society through their delivery of care.