Disinfection and sterilization of dental equipment and instruments.

It is now considered that ‘ universal precautions’ are the expected standard of care in current paediatric dental practice. The principles of universal precautions involve:

- Prevention of contamination by strictly limiting and clearly identifying a ‘ zone of contamination’.

- The need for elimination of contamination should be minimal if this zone of contamination is observed.

Universal precaution regards every patient as being potentially infectious. Although it is possible to identify some patients who are known to be infectious, there are many others who have an unknown infectious state.

It is impossible to totally eliminate infection; thus, observing universal precaution is a sensible approach to minimizing the risk of cross infection.

All children must be protected with safety glasses and clinicians must also wear protective clothing, eyeware, masks and gloves when treating patients.

Basic Definitions

1. Sterilization – Use of physical or chemical agents to destroy all microbial forms, including bacterial spores

2. Disinfection – Use of physical procedures or chemical agents to destroy most microbial forms; bacterial spores and other relatively resistant organisms e.g., mycobacteria, viruses, fungi) may remain viable; disinfectants are subdivided into high-, intermediate-, and low-level agents.

3. Antisepsis – Use of chemical agents on skin or other living tissue to inhibit or eliminate microbes; no sporicidal action is implied.

4. Germicide – Chemical agent capable of killing microbes; spores may survive.

5. Sporicide – Germicide capable of killing bacterial spores.

B. Sterilization

Physical Sterilants

a. Steam under pressure - 121єC for various times

b. Dry heat – 1 hr at 171є C; 2 hr at 160єC; 16 hr at 121єC

c. Filtration – 0.22 to 0.45мm pore size; HEPA filters

d. Ultraviolet radiation – variable exposure to 254nm wavelength

e. Ionizing radiation – variable to microwave or gamma radiation

Gas Vapor Sterilants

a. Ethylene oxide – 450 to 1200 mg/L at 29єC to 65єC for 2-5 hr

b. Formaldehdye vapor – 2% to 5% at 60єC to 80єC

c. Hydrogen peroxide vapor – 30% at 55єC to 60єC

d. Plasma gas – highly ionized hydrogen peroxide

e. Chlorine dioxide gas - variable

Chemical Sterilants

a. Peracetic acid – 0.2%

b. Glutaraldehyde – 2%

C. Disinfection (Level of Activity)

Heat

a. Moist heat - 75єC to 100єC for 30 min (high)

Liquid

a. Glutaraldehyde – 2% (high)

b. Hydrogen peroxide – 3% to 25% (high)

c. Formaldehyde – 3% to 8% (high/intermediate)

d. Chlorine dioxide – variable (high)

e. Peracetic acid – variable (high)

f. Chlorine compounds - 100 to 1000 ppm of free chlorine (high)

g. Alcohol (ethyl, isopropyl) – 70% to 90% (intermediate)

h. Phenolic compounds – 0.4% to 5.0% (intermediate/low)

I. Iodophor compounds – 30 to 50 ppm of free iodine/L (intermediate)

j. Quaternary ammonium compounds – 0.4% to 1.6% (low)

D. Antisepsis