Oral diseases, despite being largely preventable, remain a major global public health problem. Dental caries and periodontal diseases, the main oral diseases, are highly prevalent chronic conditions that have a significant negative impact on quality of life across the life course. Globally, >3 billion people suffer from untreated dental caries, making this the most common chronic disease of humankind (Marcenes et al. 2013). Oral diseases are expensive to treat, and their cost is considerable to both the individuals affected and the whole of society (Listl et al. 2015). In recent decades, significant overall improvements have occurred in levels of dental caries in many high- and middle-income countries. However, in low-income countries, caries levels appear to be increasing, linked to economic development and the associated lifestyle changes, including higher consumption of free sugars. A major concern almost everywhere in the world is the existence of stark social inequalities in oral health (Lee and Divaris 2014).