PROJECT SUMMARY/ABSTRACT Early life interactions between the microbiome and its human host are responsible for an array of immune functions and future health outcomes. It is essential to study this period during early life when the oral microbiome changes from highly dynamic infant microbiota towards a more stable adult-like microbiota. The oral microbiome plays an essential role in oral and systemic health. As such, the study of the oral microbiome may serve as a harbinger for children’s health. Understanding the establishment and early development of the oral microbiome, and its association with the early childhood caries (ECC), may provide innovative solutions for personalized, predictive, and preventive pediatric dentistry. This Mentored Research Development Award K01 study seeks to understand the dynamic changes of the oral microbiome during the first three years of life among children who were born along the United States (US)-Mexico border. These children experience a high risk of dental caries and other oral diseases; therefore, providing a complex environment for the microbiome. The study aims are: (1) to understand the establishment of newborn oral microbiome among Latinx/Hispanic children living along the US-Mexico border by using salivary samples at prenatal (from mother), 4-, 9-, 12-, 24-, 36-months to characterize their oral microbiome establishment from birth to a full set of twenty primary teeth; (2) to compare children’s oral microbiome composition between control and treatment groups (mothers received therapeutic three-month regimen of chlorhexidine mouth rinse to reduce the bacteria that causes tooth decay when their children were between the ages of four to six months) while both groups received oral health counseling; and (3) to develop statistical expertise in modeling the changes of oral microbiota and their association with ECC controlling for confounding factors. This proposed research will use three recently developed Bayesian-based ML algorithms to model the temporal patterns of the oral microbiome and evaluate their ability to predict ECC. The K01 will support Dr. Yan Wang to develop expertise in: (1) oral microbiome development in early childhood, (2) statistical analysis for oral microbiome data, and (3) biomarker discoveries using saliva samples. To achieve these training goals and research activities, Dr. Wang has assembled a highly qualified mentorship team with substantial experience in mentoring early-career investigators and with expertise in oral microbiome research among children. Dr. Wang’s primary mentors at UCLA, Dr. Grace Aldrovandi (School of Medicine) and Dr. David Wong (School of Dentistry), are highly experienced NIH-funded investigators. Co-mentor Dr. Francisco Ramos-Gomez (School of Dentistry) is a leading expert in pediatric oral health, especially among Latinx/Hispanic children. The proposed research and training aims will build strong research capacities and collaborations for Dr. Yan Wang. In ad...