Association of CBP+ Streptococcus mutans with root caries in older adults

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Due to the prolonged life expectancy and retention of teeth combined with socioeconomic limitations, physical and cognitive abilities, older patients are highly vulnerable to root caries. In the U.S, 64% of adults older than 60 years of age experience root caries. The oral pathogen Streptococcus mutans is a keystone pathogen in dental caries due to its direct association with caries initiation and development. Nearly 20% of S. mutans strains express collagen-binding proteins (CBPs), specifically Cnm and Cbm, that mediate binding to collagen- rich surfaces. Our group showed that Cnm also mediates invasion of oral epithelial cells and avid binding to dentin and root surfaces (both are rich in collagen). Using a rat caries model, we showed that Cnm contributes to oral colonization, maturation of the dental biofilm, and severity of coronal caries. Moreover, in a recent cross-sectional study with children, we observed a strong association between infection with S. mutans CBP+ strains and early childhood caries (ECC) recurrence. In cases of gingival recession, the dentin is often exposed due to physical abrasion and demineralization. As collagen is the main organic material of dentin and, considering our recent observation that CBP+ S. mutans strains are strongly associated with ECC recurrence, we hypothesize that older adults experiencing gingival recession who are also infected with CBP+ S. mutans are at greater risk of developing root caries than those infected with CBP– S. mutans strains. However, clinical evidence correlating the presence of CBP+ S. mutans strains with root caries to support this hypothesis is lacking. The goal of this supplement application is to identify microbial signatures associated with root caries in older adult populations and determine whether infection with CBP+ S. mutans strains is associated with increased risk of root caries. Thus, findings from this supplement application can lead to a paradigm shift from clinical interventions focused solely on treatment after the lesion appears to root caries prevention and treatment by integration of this information into the assessment of caries risk. Dr. Garcia's career goal is to become an independent clinician-scientist at a research-intensive dental school conducting clinical- translational research, and serving as a mentor to the next generation clinician scientists. This supplement will allow her to obtain the additional training (courses) and experience (new lab skills) to make a smooth transition into an independent career as a dentist-scientist. Additionally, an outstanding group of collegial mentors comprised of microbiologists and a dentist-scientist will work closely with the candidate to provide guidance in professional development and with the scientific aspect of this proposal.