Infection Control

Infection Control - 2 hrs

Chapter Nine - Methods of Sterilization

Chapter 1: Definitions

Chapter 2: TB / HIV / Hepatitis

Chapter 3: First Lines of Defense

Chapter 4: Personal Protective Attire

Chapter 5: General Cleaning

Chapter 6: Aseptic Technique

Chapter 7: Chemical Disinfectants

Chapter 8: Steps in Instrument Processing

Chapter 9: Methods of Sterilization

Introduction

Sterilization Monitoring

Glutaraldehyde as a

Sterilant

Chapter 10: The Dental Laboratory

Chapter 11: Waterlines

Chapter 12: Ethical and Legal Considerations Regarding AIDS and HIV

Chapter 13: Summary Checklists

Bibliography and Suggested Reading List

Introduction

Methods of Sterilization
METHOD	STANDARD STERILIZING CONDITIONS*	ADVANTAGES	PRECAUTIONS	SPORE-TESTING
Steam autoclave	20-30 min at 250 F 3-10 min at 273 F	Time efficient; Good penetration; Sterilize water-based liquid	Do not use closed containers; May damage plastic and rubber items; non-stainless steel metal items corrode; Use of hard water may leave deposits	Bacillus stearothermophilus strips, vials, or ampules.
Unsaturated chemical vapor	20 min at 270 F (20-40 psi)	Time efficient; No corrosion; Items dry quickly after cycle	Do not use closed containers; May damage plastic and rubber items; Must use special solution; Predry instruments or dip in special solution; Provide adequate ventilation; cannot sterilize liquids.	Bacillus stearothermophilus strips
Dry heat oven Dry heat	60-120 min at 320 F	No corrosion; Can use closed containers; Large capacity per cost; items are dry after cycle	Longer sterilization time; cannot sterilize liquids; May damage plastic and rubber items; Do not open door before end of cycle	Bacillus subtilis strips
Rapid Heat Transfer	12 min at 375 F (for wrapped items) 6 min at 375 F (for unwrapped items	No corrosion; Short cycle; items are dry after cycle.	Predry instruments; Cannot sterilize liquids; May damage plastic and rubber items; Do not open door before end of cycle; Small capacity per cost; Unwrapped items quickly contaminated after cycle.	Bacillus subtilis strips
* These conditions do not include warm-up time and they may vary depending upon the nature and volume of the load. Sterilizing conditions in your office sterilizer should be defined by results of routine spore-testing.
C.H. Miller. "Sterilization and disinfection: what every dentist needs to know.", JADA vol 123:46 © 1992 Reprinted by permission of ADA Publishing Co., Inc.

The Centers for Disease Control and the American Dental Association recommend sterilization of any instruments, burs, and handpieces that come into contact with oral tissue, or penetrate soft tissue or bone after each use. An adequate sterilization procedure must kill all microorganisms present on the item being sterilized.

Heat stable critical and semi-critical instruments shall be cleaned and sterilized before use by using steam under pressure (autoclaving), dry heat, or chemical vapor. FDA cleared chemical sterilants/disinfectants shall be used for sterilization of heat-sensitive critical items and for high-level disinfection of heat-sensitive semi-critical items.

Critical and semi-critical instruments or containers of critical and semi-critical instruments sterilized by a heat or vapor method shall be packaged or wrapped before sterilization if they are not to be used immediately after being sterilized. These packages or containers shall remain sealed unless the instruments within them are placed onto a setup tray and covered with a moisture impervious barrier on the day the instruments will be used and shall be stored in a manner so as to prevent contamination.

A process cannot be called "sterilization" unless it kills all bacterial spores, the most difficult of microorganisms to kill. The four main sterilizing methods used in dentistry today are steam heat autoclave, unsaturated chemical vapor, dry heat, and rapid heat transfer. The effectiveness of these types of sterilizers can be tested with commercial spore testing. Precleaned instruments submerged in glutaraldehyde solution at 2.0 percent or 3.2 percent concentration for 10 hours will also kill bacterial spores, but there is no test to verify the results. Currently, no single system will work for all the items used in a dental office. Most offices use steam autoclaves as a primary source of sterilization with glutaraldehyde as a secondary.

The best and safest approach to preventing disease transmission from patient to patient via the instruments is to sterilize all reusable instruments that are contaminated with blood or saliva instead of sterilizing some and disinfecting others. Sterilizers must be used correctly to achieve sterilization with every load of instruments.

Examples of common mistakes include:

overloading of sterilizer chamber;
lack of separation between packs or trays in the chamber;
wrong packaging material for method of sterilization;
more than two layers of wrap, inhibiting penetration;
closed container not penetrated by steam or chemical vapor;
starting timing for sterilization before sterilizing temperature is reached;
dry heat sterilizer door opened to add more items without starting sterilization time over;
sterilizer timer malfunction;
sterilizer malfunction; and
improper cleaning of items to be sterilized. i

Continue on to Sterilization Monitoring