There are two important things to do in a dental office in order to prevent cross infection. These two forms are sterilization and disinfection. According to the CDC and the Food and Drug Administration before either of these forms can be used you have to clean the instruments. This can be done either by hand or by using an ultrasonic cleaner.
(http://www.maexamhelp.com/instru_sterilization.htm)

Even though both sterilization and disinfection are both important there is a big difference between the two. Sterilization is the process of killing all microorganisms. Where disinfection is the process of destroying pathogenic organisms or rendering them inert. The centers for disease control says there is one cardinal rule for infection control which is “Do not disinfect when you can sterilize” (http://www.maexamhelp.com/instru_sterilization.htm).