Book excerpt: Scientific Knowledge in Controversy: The Social Dynamics of the Fluoridation Debate is a study of today's most heated and long-lived health controversy as well as a study of the role of power in science. It uses the tools of sociology of knowledge and political economy to analyze battles over scientific evidence and the struggle for scientific credibility, the exercise of professional power to suppress opponents, and the role of corporate interests in the debate. The evidence from a variety of countries offers a new perspective on the fluoridation issue and also shows how to link the analysis of rhetoric in scientific disputes with the wider analysis of power in society.