1. Infection control and Sterilization
Operative Dentistry
معالجة / د . زينة (م 3)
Infection control and Sterilization
Dr. Zena Ammar Ahmed

2. Definitions:
INFECTION CONTROL – also called “exposure control plan”, is a required office program that is designed to protect personnel against risks of exposure to infection.
Disinfection refers to the destruction of pathogenic organisms but not bacterial spores, by direct exposure to chemical and physical agents.
Sterilization: use of a physical or chemical procedure to destroy all microorganisms including substantial numbers of resistant bacterial spores. Should be used for all instruments which come in contact with blood or saliva.

3. Disinfectants Versus Antiseptics
Disinfectants are chemicals that are applied to inanimate surfaces (such as countertops and dental equipment).
Antiseptics are antimicrobial agents that are applied to living tissue (skin or mucous membrane) to prevent infection by inhibiting the growth of bacteria.

4. Disease Transmission in the Dental Office
Every dental office should have an infection control program designed to prevent the transmission of disease from:
Patient to dental team
Dental team to patient
Patient to patient
Dental office to community (includes dental team’s family)
Community to patient

5. Disease Transmission in the Dental Office
Transmitted by inhalation:
Chicken pox, Measles & Mumps, Common cold, Tuberculosis, German Measles, Candidosis.
Transmitted by inoculation:
Hepatitis, Oral herpes, herpetic whitlow, AIDS, Syphilis, Wound abscess.

6. Sterilization and disinfection
-Personal barrier protection.
-Dental unit and environmental surfaces disinfection.
-Dental instruments sterilization.

7. :PERSONAL BARRIER PROTECTION
The various barriers are gloves, masks, protective eye wear, and surgical head cap.
Precautions to avoid injury exposure, Sharp end of instruments must be pointed away from the hand
Avoid handling large number of sharp devices.
At the beginning of a routine treatment period, watches and jewelry must be removed.
Hands must be washed BEFORE and AFTER treating each patient, Before putting on gloves and Immediately after removing gloves with a suitable cleanser.

8. :Hand cleansers
Chlorhexidine based – these contain 2- 4% chlorhexidine gluconate with 4% isopropyl alcohol in a detergent solution with a pH of 5.0 to 6.5. They have broader activity for special cleansing. But it can be hazardous to eyes.
Povidone iodone – contain % povidone iodine, used as a surgical hand scrub.
Alcohol hand rubs- ethyl alcohol and isopropyl alcohol are widely used at 70% concentration. They are rapidly germicidal when applied to the skin. Alcohols should not be applied to wounds since they can cause tissue damage

9. Dental unit and environmental surfaces disinfection
In the dental operatory, environmental surfaces (i.e., a surface or equipment that does not contact patients directly) can become contaminated during patient care. Certain surfaces, especially ones touched frequently (e.g., light handles, unit switches, and drawer knobs) can serve as reservoirs of microbial contamination.
Disposible toweling should be used whenever possible.

10. Dental unit and environmental surfaces disinfection
Disinfection is always at least a two-step procedure:
The initial step involves scrubbing of the surfaces to be disinfected and wiping them clean.
The second step involves wetting the surface with a disinfectant and leaving it wet for the time prescribed by the manufacturer(usually 10 min.)
However, if such products are unavailable, a 1:100 dilution of sodium hypochlorite (e.g., approximately ¼ cup of 5.25% household chlorine bleach to 1 gallon of water) is an inexpensive and effective disinfecting agent.

11. :Types of Chemical Disinfectants
Iodophors organic compounds that slow the release of iodine. Because iodophors contain iodine, they may corrode or discolor certain metals and may temporarily cause reddish or yellow stains on clothing and other surfaces. Betadine and Isodine are examples of iodophors
Synthetic phenol compounds are intermediate-level hospital disinfectants with broad-spectrum disinfecting action. Phenols can be used on metal, glass, rubber, or plastic. They also may be used as a holding solution for instruments.

12. :Types of Chemical Disinfectants
Sodium hypochlorite (household bleach) is a fast-acting, economic, and broad-spectrum intermediate-level disinfectant (1:100 dilution for surface decontamination).
Disadvantages: It is unstable and must be prepared daily, has a strong odor and is corrosive to some metals. It is also destructive to fabrics and irritating to the eyes and skin.
Glutaraldehyde: is capable of sterilizing equipment, though to effect sterilization often requires many hours of exposure.

13. Sterilization and disinfection of dental instruments

14. Principles and procedures for handling and cleaning instruments after treatment
The safest and most efficient instrument cleaning procedures involve ultrasonic cleaning of used instruments kept in a perforated basket or cassette throughout the cleaning procedure.
Used instruments are commonly placed in an anti microbial solution as this softens and loosens debris.
Next, move the basket of instruments into an ultrasonic cleaning device, rinse them, and then carefully inspect the instruments for debris.
Dip instruments likely to rust into a rust inhibitor solution. Drain & dry instruments with absorbent towel.

15. Ultrasonic cleaners and solutions
An ultrasonic cleaner uses sound waves, that are outside the human hearing range to form oscillating bubbles, a process called cavitation.
These bubbles act on debris to remove it from the instruments.
Ultrasonic cleaning is the safest and most efficient way to clean sharp instruments.

16. The most accepted methods of instrument sterilization are :
Steam pressure sterilization (autoclave)
Chemical vapor pressure sterilization- (chemiclave)
Dry heat sterilization (Oven)
Others
-Exposure to ethylene oxide gas
-Boiling water
-Ionizing radiation

17. Steam pressure sterilization (autoclave)
An autoclave is a high pressure device used to allow the application of moist heat above the normal-atmosphere boiling point of water
Exposure to 121ºC for 15+ minutes is typically sufficient to sterilize
Again, the material must be 121ºC before the clock starts
Large items, large volumes, and items that are poorly penetrated by steam may take much longer than 15 minutes to sterilize

18. Steam pressure sterilization (autoclaving)
Advantages
Rapid and effective
Effective for sterilizing cloth surgical packs and towel packs
Disadvantages
Items sensitive to heat cannot be sterilized
It tends to corrode carbon steel burs and instruments

19. Chemical vapor under pressure Sterilization (chemiclave)
operates at 1310 C and 20 lbs of pressure.
They have a cycle time of half an hour.

20. Chemical vapor under pressure Sterilization (chemiclave)
Advantages
Carbon steel and other carbon sensitive burs, instruments and pliers are sterilized without rust or corrosion
Disadvantages
Items sensitive to elevated temperature will be damaged
Instruments must be very lightly packed.
Towel and heavy clothing cannot be sterilized.

21. Dry heat sterilization
Conventional Dry Heat Ovens have heated chambers that allow air to circulate by gravity flow.
It also is less penetrating and requires longer exposure.
Nevertheless, application of dry heat is cheap and easy
The most accurate way to calibrate a sterilization cycle is by using external temperature gauge (pyrometer) attached to a thermocouple wire.

22. Dry heat sterilization
To effect sterilization dry heat typically requires higher temperatures than moist heat.
Short-Cycle, High Temperature achieved at temperature above 1600 C.
Typically one bakes materials in an oven at:
170ºC for at least one hour
160ºC for at least two hours
180ºC for at least ½ hours

23. Advantages of Dry Heat Sterilization
Carbon steel instruments and burs do not rust, corrode, if they are well dried before processing.
Industrial forced-draft hot air ovens usually provide a larger capacity at a reasonable price.
Rapid cycles are possible at high temperatures.

24. Disadvantages of Dry Heat Sterilization
High temperatures may damage more heat-sensitive items, such as- rubber or plastic goods.
Sterilization cycles are prolonged at the lower temperatures.
Must be calibrated and monitored, more chances sterilization failures.

25. Ethylene oxide sterilization (ETO)
Ethylene oxide: is a gaseous chemosterilizer that is especially useful due to its extraordinary penetrating power. It is an inflammable and potentially explosive gas. By mixing with inert gases like CO2 and N2 to concentration of 10% its explosive tendency is eliminated. cause DNA damage of bacteria.

26. Ethylene oxide sterilization (ETO)
Advantages:
Operates effectively at low temperatures.
Gas is extremely penetrative.
Can be used for sensitive equipment like handpieces. Equipment that is otherwise destroyed by heat (e.g., plastic petri dishes, glass, Paper).
Disadvantages:
Potentially mutagenic and carcinogenic.
Requires aeration chamber ,cycle time lasts hours.
Usually only hospital based.

27. Ionisizing radiation:
High energy ionizing type (Gamma rays and high energy electrons such as X-rays and cosmic rays)
Action: cause DNA damage of bacteria.
For the sterilization of antibiotics, hormones and other prepacked disposable items such as catheters, gloves, syringes, infusion sets, etc.
They are expensive.
They are very effective due to high penetrative power.

28. Ozone:
Ozone sterilization is the newest low-temperature sterilization method recently introduced in the US and is suitable for many heat sensitive and moisture sensitive or moisture stable medical devices.
Ozone sterilization is compatible with stainless steel instruments.
Ozone Parameters • The cycle time is approximately 4.5 hours, at a temperature of 850F – 940F.