 By the 1930s, the theory of focal infection began to be reexamined, and new research shed doubt on the results of previous studies.A 1935 "Journal of the Canadian Dental Association" article called Price radical, while citing his comment in "Dental Infections, Oral and Systemic" of "continually seeing patients suffering more from the inconvenience and difficulties of mastication and nourishment than they did from the lesions from which their physician or dentist had sought to give them relief" as a good reason for the use of tooth extraction to be minimized.One researcher in 1940 noted "practically every investigation dealing with the pulpless teeth made prior to 1936 is invalid in the light of recent studies" and that the research of Price and others suffered from technical limitations and questionable interpretations of results.