Functional dentition plays an important role in maintaining masticatory function, which is closely related to the number of teeth present in the mouth. The objective of this study was to investigate the association between individual and contextual factors and functional dentition (defined as the presence of at least 20 teeth) in Brazilian adults. This was a multilevel cross-sectional population-based study with a two-level structure and a total sample of 10,407 adults from 84 municipalities (counties). The exposures at both levels were demographic, socioeconomic, and oral health treatment-related. Multivariate analyses showed that higher prevalence rates of functional dentition were associated (p < 0.01) with municipalities having higher mean income and fluoridated water supply and with individuals living in urban areas, younger adults, males, those with more schooling and higher income, those that reported having visited the dentist in the previous 12 months, and those with access to information on prevention. The findings suggest that research on tooth loss and functional dentition should take different socioeconomic factors into account.