Reporting the economic burden of oral diseases is important to evaluate the societal relevance of preventing and addressing oral diseases. In addition to treatment costs, there are indirect costs to consider, mainly in terms of productivity losses due to absenteeism from work. The purpose of the present study was to estimate the direct and indirect costs of dental diseases worldwide to approximate the global economic impact. Estimation of direct treatment costs was based on a systematic approach. For estimation of indirect costs, an approach suggested by the World Health Organization’s Commission on Macroeconomics and Health was employed, which factored in 2010 values of gross domestic product per capita as provided by the International Monetary Fund and oral burden of disease estimates from the 2010 Global Burden of Disease Study. Direct treatment costs due to dental diseases worldwide were estimated at US$298 billion yearly, corresponding to an average of 4.6% of global health expenditure. Indirect costs due to dental diseases worldwide amounted to US$144 billion yearly, corresponding to economic losses within the range of the 10 most frequent global causes of death. Within the limitations of currently available data sources and methodologies, these findings suggest that the global economic impact of dental diseases amounted to US$442 billion in 2010. Improvements in population oral health may imply substantial economic benefits not only in terms of reduced treatment costs but also because of fewer productivity losses in the labor market.

Nonsyndromic cleft lip with or without cleft palate has been associated with SNPs in the IRF6 gene. Now Jeff Murray and colleagues report the identification of a common variant in a previously unknown IRF6 enhancer that shows strong evidence of association with cleft lip only and disrupts the binding site of transcription factor AP-2α. Previously we have shown that nonsyndromic cleft lip with or without cleft palate (NSCL/P)1 is strongly associated with SNPs in IRF6 (interferon regulatory factor 6)2. Here, we use multispecies sequence comparisons to identify a common SNP (rs642961, G>A) in a newly identified IRF6 enhancer. The A allele is significantly overtransmitted (P = 1 × 10−11) in families with NSCL/P, in particular those with cleft lip but not cleft palate. Further, there is a dosage effect of the A allele, with a relative risk for cleft lip of 1.68 for the AG genotype and 2.40 for the AA genotype. EMSA and ChIP assays demonstrate that the risk allele disrupts the binding site of transcription factor AP-2α and expression analysis in the mouse localizes the enhancer activity to craniofacial and limb structures. Our findings place IRF6 and AP-2α in the same developmental pathway and identify a high-frequency variant in a regulatory element contributing substantially to a common, complex disorder.

Classical descriptive epidemiology in the field of cleft lip and palate aims to quantify the problem, and in the higher income countries it is possible to do this with varying degrees of accuracy. This is not however possible in every country in the world, and epidemiology should seek to identify these data gaps with a view to improvement in the situation. Epidemiology must also be investigative and look for trends, associations and inter-population differences, with the aim of supporting aetiological research and advancing the translational agenda. This chapter is set out in three parts and seeks to address all three of the above areas. Birth defects in general and orofacial clefting in particular remain a relatively common and significant problem for not only the individual patients born with these defects in terms of death or disability, but also for their families and for society in general in terms of burden of care and health inequality. In high-income countries, despite very significant advances in treatment, problems in access to care and evidence base for cleft care still exist whereas in the developing world the consequences are lack of access to care and lack of infrastructure to help with quantification of the problem and consequently the ability to address it. The major questions in contemporary cleft lip and palate research surround ways of improving the evidence base for the treatment interventions used to optimise quality of care, and the ultimate scientific and humanitarian objective is primary prevention of those diseases and disorders that are preventable. Descriptive epidemiology underpins research enquiry in both of these major areas.