Semi-critical instruments are defined as instruments that:

Semi-critical instruments are defined as those that come into contact with mucous membranes or non-intact skin but do not penetrate soft tissue. This distinction is important in infection control because these instruments may harbor pathogens that could be transmitted if not properly managed. Therefore, they require careful disinfection between uses to prevent the risk of infection during dental procedures.

While semi-critical instruments can often be high-level disinfected instead of sterilized, the necessity for disinfection comes from their contact with bodily tissues. Proper handling and maintenance of these instruments are crucial to safeguarding both patient health and safety during dental procedures.