sterilization in operative dentistry

1. 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.

2. 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.

3.  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 hours
Advantages:
 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.

4. 
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.

5.  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

6.  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.

7.  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.


8.  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.


9. 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

10.  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