Dr. Levi Spear Parmly (1790-1859), an influential American figure in the field of dental prevention, introduced flossing as the most efficient way to prevent dental disease. Dr. Parmly practiced in the United States, England and France. Many of his ideas about controlling dental diseases are still highly applicable to modern clinical practice. In this century, Dr. Charles C. Bass (of New Orleans) and Dr. Sumter S. Arnim (of Houston) rediscovered, expanded, and publicized the principles, ideals and practices of Dr. Parmly. As a result, Parmly's concepts relating to oral disease causation and control continue to influence today's dental practitioners. His seminal work and thoughts concerning preventive dentistry are presented in this biographical paper.