How to properly clean/sterilize the dental instruments

The proper handling of dental instruments should result in entirely free from bacteria, viruses, and spores.  The high incidents of hepatitis and its frequent lack of clinical symptoms make it necessary to presume that all patients are potential carriers and make it imperative to sterilize dental instruments.

Disinfect the instruments if sterilization is not possible.

Sterilization is the destruction of all microbial forms, including viruses through steam under pressure (autoclave), prolonged dry heat, or chemical vapor.

Disinfection is the destruction of some pathogenic microorganism only through the use of chemicals or heat. It is incapable of destroying spores and certain resistant pathogens, e.g., tubercle bacilli and hepatitis viruses. Since disinfection can not kill all pathogenic microbes, those remaining may transmit infection.

Guidelines for infection control in dental health care settings according to the Centers for Disease Control based on the types/usage of instruments.

Based on the usage, dental instruments are classified as:
  1. Critical instruments include the instruments that penetrate soft tissue or bone or contact with blood such as scalpels, forceps for extraction, and scalers. These instruments sterilized by either autoclaving, dry heat or chemical vapor.

  2. Semi-critical instruments include the devices that contact mucous membranes inside the oral cavity without penetrating soft tissue or bone.  For example;  a mirror used in the oral examination, tools for placing fillings, reusable impression trays for prosthesis, high-speed and low-speed handpieces.  Use the same sterilization method as mentioned in critical instruments. If sterilization is not feasible, use high-level disinfection. A high-level disinfectant is registered with the EPA as a "sterilant/disinfectant."

  3. Non-critical instruments include the instruments that come into contact with skin only such as blood pressure cuffs, x-ray heads. These instruments may be cleaned between patients by intermediate-level or low-level disinfect.
An intermediate-level disinfection is EPA-registered as a "Hospital disinfection" with a label "Tuberculocidal" activity (such as phenolics, iodophors, and chlorine-containing compounds).

A low-level disinfection is EPA-registered as a "Hospital disinfection" but is not labeled for "Tuberculocidal" activity (such as quaternary ammonium compounds).

All heat sensitive instruments use cold sterilization with liquid chemical germicides for up to 10 hours, rinse with sterile water, dried, and placed in a sterile container if not used immediately.  Liquid chemical germicides registered with the EPA as a "Sterilant/disinfectant."

Before sterilization or high-level disinfection, soak the instruments in water or disinfectant/detergent after each use as soon as possible to prevent drying of debris. Cleaning all debris with Instrument cassettes or mechanical cleaning such as ultrasonic cleaners to reduce direct handling of contaminated instruments. Wear heavy-duty gloves when cleaning or handling contaminated instruments.

After cleaning, rinse the instruments and let them dry before packaging them for autoclaving, dry heat, or heat/chemical vapor. Packaging the instruments before sterilization prevents contamination after completing the cycle.

Verify proper function of sterilization cycles by periodic use of:

  1. Biological indicators - spore tests.
    • To monitor steam, and unsaturated chemical vapor sterilizers use  Bacillus(Geobacillus) stearothermophilus 
    • To monitor the dry heat sterilizer uses Bacillussubtilis

  2. Chemical indicators - tape, strips, tabs and distinctive markings on packaging material) indicate exposure to heat

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