Which of the following is an example of a critical instrument?

Critical instruments are those that penetrate soft tissue or bone and carry a high risk of infection if not properly sterilized. An example of a critical instrument is bone chisels, as they are used in dental procedures that involve cutting into bone or soft tissue. Because these instruments come into contact with blood and other fluids, they must be sterilized between each use to prevent the transmission of pathogens.

In contrast, the dental x-ray tubehead and the lead apron are considered non-critical items. Non-critical instruments may come into contact with intact skin but do not penetrate tissue, thus presenting a lower risk of infection. The exposure button is also a non-critical item, as it typically only requires routine cleaning and disinfection rather than sterilization. Understanding the classification of instruments based on their level of risk is crucial for effective infection control practices in the dental environment.