“…These guidelines are periodically updated, because an effective control of HBV transmission is unfeasible without an evidence based assessment of the risk for infection in dental healthcare settings 10 . This assessment is essential to understand that, for example, HBV transmission is unlikely through dental unit wa terlines, although oral fluid retraction is com mon during turbine use and microorganisms can be transmitted between patients through this route, despite turbine change or steriliza tion 11 ; or that effective dental healthcare work ers' immunization requires that guidelines are not imposed, but proposed, because the mere knowledge of the risk of HBV infection does not necessarily result in high compliance to ward guidelines 12,13 .…”