LAUSR

The oral cavity has the second largest and most diverse microbiota of the human body, harbouring over 700 microbial species [1]. Oral microbial communities are dominated by bacteria, but also contain archaea, viruses, and eukaryotes, whose roles in oral health and disease are less well understood [2]. Lifestyle, diet, and other hostrelated factors, such as ethnicity or ancestry, are associated with the composition of these microbial communities, and oral microbiome variation may affect the assessment, response, and effectiveness of disease interventions [3,4]. Therefore, it is necessary to understand how oral microbiome traits are associated with oral health in diverse human populations. Currently, microbiome research is dominated by gut microbiome studies and is strongly biased towards populations of European descent [5]. Such populations, by definition, provide a poor basis from which to understand microbiome-health relationships in under-studied populations, including groups who carry the highest burdens of disease. A similar bias is present in the oral microbiome research field. Many oral microbiome studies are conducted primarily on people living in industrialized countries, such as the United States and China. These countries maintain large funding allocations for biomedical research; for example, the United States National Institutes of Health (NIH) invested approximately USD $728 M in human microbiome research over a five-year period (2012-2016), of which $48 M was utilized for oral microbiome research [6]. Nevertheless, oral microbiome research within the United States has produced relatively few studies that include people from non-European backgrounds (e.g. African Americans or people of Asian or Indigenous ancestry), and even fewer of these specifically investigate non-bacterial members of the oral microbiota. The NIH Revitalization Act mandates the inclusion of racial and ethnic minorities in federally funded biomedical research, but the implementation of this mandate has been problematic [7]. In the global context, it is not unusual to observe oral microbiome studies using inconsistent or problematic racial and ethnic categories, or failing to mention participants’ race, ethnicity or