“…These comprise low education and/or low income (Guarnizo-Herreno et al, 2014;Sanders & Spencer, 2005;Trachte, Geyer, & Sperlich, 2016;Turrell, Sanders, Slade, Spencer, & Marcenes, 2007), smoking (Csikar et al, 2016), frequent stress events, or obesity (Lee, Song, Yang, & Kang, 2015). Also, overt symptoms of oral disease contribute to poor rating, such as the number of lacking teeth, difficulty in mastication, or xerostomia (Ohara et al, 2015). Moreover, the frequency of dental attendance seems to be a factor (Northridge et al, 2012).…”