Sterilization and Disinfection of Instruments and Equipment
Spaulding classification drives the method
Classify every item before choosing a process. Critical items penetrate soft tissue or enter the bloodstream-forceps, scalpel blades, surgical burs-and must be sterile. Semicritical items contact mucous membranes but do not penetrate-mirrors, amalgam condensers, oral evacuation tips-and must be sterile or, if heat-sensitive, receive high-level disinfection. Noncritical items touch intact skin-blood pressure cuffs, extraoral radiograph equipment-and need intermediate- or low-level disinfection.
Cleaning, packaging, and sterilization
Cleaning removes bioburden; sterilization kills all microorganisms but does not clean. Use an ultrasonic cleaner or washer-disinfector, dry the instruments, inspect for debris, and package in pouches or wrap that allows steam penetration. Do not overload the chamber. Steam autoclave cycles commonly run 121°C (250°F) at 15 psi for 15–20 minutes, or 132°C (270°F) at 30 psi for 4–6 minutes; follow the manufacturer’s instructions. Heat-sensitive items may use ethylene oxide or chemical sterilants. High-level disinfectants such as glutaraldehyde or OPA require immersion and adequate contact time.
Monitoring and traps
Monitor every load with mechanical gauges and a chemical indicator inside the package; use a biological indicator (spore test) at least weekly and for every load containing implants. Geobacillus stearothermophilus tests steam; Bacillus atrophaeus tests dry heat and ethylene oxide. A positive spore test means recall and reprocess. Traps include treating a chemical indicator as proof of sterilization and assuming handpieces can be wiped rather than sterilized. Worked example: a heat-sensitive semicritical camera-high-level disinfect it, not just wipe with a low-level disinfectant. Rule of thumb: critical = sterile; semicritical = sterile or high-level disinfection.