Sterilization

Sterilization: it is a way that kills all living microorganism including bacteria, viruses to prevent cross infection from patient to patient.

Disinfection: a much lesser term of sterilization and indicate procedure offering variable measure of control of infection, in this way we not going to kill all living m.o. may viruses kept survive.

Method of sterilization

Physical method

Chemical method

Combination of both

Physical sterilization Boiling water: widely used, easy and economic.

Disadvantages

Rusting of the instruments.

The instruments are going to be dull under 100c for 30 min. to minimized rusting we added sodium bicarbonate which inhibits the rusting.

Dry heat: hot air oven is widely used in dentistry because it's efficient than boiling water and economic. Two points should put in consideration ((temperature &time)).

The recommended temp.150 c˚ for 1-1.5 hoursAdvantages: If we use it under 150 c we can use it for

sterilization of paper points, cotton roll, and dressing.

Some kinds of hand pieces don’t contain plastic part in them, we can sterilize them by this method after they clean and should be oiled.

Materials to be sterilized can be sealed before sterilization in metal boxes, will remain sterilized for long period of time.

The cost is less than 1/2 of that of portable autoclave.

Disadvantages:

High temp. required will affect the sharpness of the instrument, it will break the mirror and will melt the plastic handle of the reamers

The process is slow

It is easy for the dentist to interfere with the process any time, so never guarantee the sterilization.

Autoclave : the most efficient method in dentistry(heat under pressure) for 15 min., 170 c under pressure 20 pounds/inch, so we destroy most organisms '' viruses, fungi and spores in relatively short time.

Disadvantages: rusting of the instruments, so to minimize this we added sodium nitrate 1%.this method is effective for (reamer, file and hypodermic syringe)

The most widely used methods is (dry heat)

The most effective method is (autoclave

Hot-oil method: mainly used for hand pieces, the sterilization for 15 min. under 150c temp.

Ultrasonic vibration method: used especially for reamer, file and burs.

Advantages:

16 times more effective than hand scarping

Erosion of the instrument is less.

Decrease puncturing wound by the contaminating instrument; we consider this method as cleaning more than sterilizing.

Radiation: using U.V. light, Gamma, and beta rays. It is expensive but effective method. We use it especially for disposable needles and drugs.

Gas method: ethylene oxide used which is highly bacterocidal. Hand piece sterilize by this method.

Chemical sterilization

All chemicals are poor alternative to physical ways. Disinfection antiseptics don’t kill all spores.

They act: Reacting with cell portion of the bacteria. Reacting with enzyme system of the bacteria. Cause destruction of the cell wall of the bacteria.

Properties of ideal antiseptics: Destroy the microorganism Should penetrate deeply through the bacterial cells Rapid in action Return its potency Soluble in water Not corrosive Don’t stain the instruments Don’t damage materials or living tissue when come in contact.

Important points for disinfection

Concentration: we should follow the instruction of each agent, if we ↑concentration →↓ time

Time of exposure: not all organisms are killed immediately, so we need longer time especially in the presence of organic material.

Temperature: when increase temperature we get efficient sterilization.

PH: each agent has special PH act perfectly on it. The presences of contaminated m.o. take more

time.

Chemicals used as bacteriocidal like:

Eugenol: - it is a light yellow solution should be kept in a dark container. The action of eugenol is paralysis of the nerve ending, that why it is consider as a good sedation.

We use it in temporary filling, it is soluble in water, so use water in cutting temporary filling, to dissolve eugenol, so decrease sensitivity during cutting.

Alcohol: - widely used in 70 % concentration, it will act perfectly.

Cmcp: - which is camphorated mono chloro phenol, used dressing in R.C.T.

Chlorohexidine: - used as mouth wash, hand wash, it can be used as mouth wash in dental clinic, before dental procedure. it keeps the mouth clean for the time of dental procedure.

H2 O2:- used to irrigate the R.C.T

Combination method: (Temperature +pressure+ chemicals) This method used vapor created by heating alcohol

formaldehyde under pressure. The temp. 130c, time 20-25 min., pressure20 pounds/ inch we can gain a very good sterilization, but it is very expensive, so we use it in big operation.

Advantages: Short time No rusting Availability of immediate dryness Useable of instrument with no delay for airing

Infection control program in minimum dental office Sterilization of instrument Comprehensive medical history Hepatitis B vaccine to prevent any cross infection Antiseptics and mouth wash Disposable mask and gloves Protective eye glass Rubber dam Sharp instruments Surface cleaning and cover tray