As more people keep their own teeth as they age, dental caries, or cavities, are becoming more common. So, new strategies for prevention and treatment are needed, especially for root caries. There is a thriving resident microbial community in our mouths, much of which forms biofilms, complex communities that attach to surfaces like teeth. Recent studies have examined the role of this oral microbiome in caries formation, but the research models usually include only one or a few microbial species, and none allow the study of diverse natural biofilms. So researchers developed two models of root caries using complex biofilms to study prevention approaches. The pre-treatment model mimicked clinical dental varnish use, and the post-treatment model represented home mouthwash use. Sequencing analysis revealed strong microbial diversity in both models and the presence of microbes found in caries lesions, but the pre-treatment model was more effective than the post-treatment model in controlling the microbes that cause caries. These models can be used to compare the effectiveness of different caries prevention and treatment strategies and to develop better products to protect teeth against root caries.