A commentary on a flawed public health investigation.

The possibility of hepatitis C being transmitted between dental patients was the genesis of an extensive and expensive look-back investigation conducted by an Ontario Public Health Unit. This investigation was performed with a minimal knowledge of nosocomial infections of dental origin, an enthusiastic reliance on untested checklist indicators and an absence of any of the criteria justifying such an investigation. As a consequence, the entire exercise was based on the false premise that an infection control lapse had occurred. This commentary will address these flaws, and other aspects of the Public Health Unit's response that detracted from its credibility. The provision of a realistic assessment of disease transmission in dentistry should result in Public Health Units conducting informed and mutually beneficial inspections of dental practices.