Dr. Warren joined the University of Iowa College of Dentistry as a postdoctoral associate in 1991. He became an adjunct assistant professor in the Department of Preventive & Community Dentistry in 1996. In 1999, he became a full-time assistant professor in the department; he is now a professor. In 2010, Dr. Warren became director of the graduate program in dental public health.
Dr. Warren teaches both predoctoral and graduate classes. His main predoctoral responsibilities include clinical preventive dentistry, but he also participates in the community dentistry courses. His graduate responsibilities include directing a course in thesis research design as well as participating in several other courses. He is also graduate program director for dental public health.
Dr. Warren's clinical activities include teaching in the predoctoral preventive dentistry clinics and various clinical research projects.
Dr. Warren's current research includes several studies of factors related to dental caries in early childhood and the prevention of this disease; longitudinal sucking patterns and dental arch development; and longitudinal study of fluoride exposures and dental fluorosis. Dr. Warren is also the director of the College of Dentistry's student research program.
Dr. Warren is a calibrated examiner for the Iowa Fluoride Study and he helped develop examination criteria for epidemiological dental caries and dental fluorosis examinations in the primary dentition. Dr. Warren has served as a consultant to several oral health studies in the United State and abroad, and has served on several NIH and international grant review panels. Dr. Warren has been a member of the editorial board for Journal of Public Health Dentistry and currently serves in that capacity for Special Care Dentistry. He is a reviewer for Community Dentistry and Oral Epidemiology, Special Care in Dentistry, Caries Research, Caries Research, and a number of other journals.