What type of instruments contacts mucous membranes without penetrating body tissues?

The correct answer is semicritical instruments. These instruments are designed to contact mucous membranes or non-intact skin but do not penetrate body tissues. Examples include tools like dental mouth mirrors and ultrasonic scaler tips, which come in contact with areas that require a higher level of disinfection than noncritical instruments but do not enter sterile body cavities.

Semicritical instruments must be thoroughly disinfected and sterilized because they can potentially harbor pathogens due to their contact with mucous membranes. The classification is important in infection control, as the level of cleaning and disinfection needed varies based on how the instrument will be used.

Critical instruments, in contrast, are those that enter sterile body tissues or the vascular system, requiring complete sterilization before use. Noncritical instruments only touch intact skin and can usually be cleaned with routine surface disinfectants. Disposable instruments, while designed for single use and to prevent cross-contamination, do not fall into the category that involves contact with mucous membranes, making them distinct from semicritical instruments.