Which of the following is classified as a SEMI-CRITICAL dental instrument?

Correct answer: B. Dental scaler

• A. Digital radiographic sensors are semi-critical (they contact mucosa) but are heat-sensitive and CANNOT be heat-sterilized. They require a patient-specific barrier (plastic sleeve) plus surface disinfection — but the classification is semi-critical. This answer may be considered tricky: sensors are semi-critical in contact level but barrier-protected rather than sterilized.
• B. CORRECT. Semi-critical items contact mucous membranes or non-intact skin but do not penetrate soft tissue or bone. Scalers contact the gingival mucosa and subgingival tissues; they require sterilization (heat sterilization) between patients. Scalers are heat-tolerant and must be sterilized, not just disinfected.
• C. The dental chair is a non-critical item that contacts intact skin and requires routine surface disinfection.
• D. A blood pressure cuff is a non-critical item — it contacts intact skin and requires only low-level disinfection between patients.