7. Sterilization in Dentistry
Sterilization procedures are very
important to any good dental practice
Patients mouth are teeming with
microbes.
As Dental unit come across large
number of patients , an inherent
potential for spreading infectious
germs between patients and dental
staff, through contaminated
instruments and surfaces.
7
8. Why we need
Sterilization?
Microorganisms capable of causing
infection are constantly present in the
external environment and on the
human body.
Microorganisms are responsible for
contamination and infection.
The aim of sterilization is to remove or
destroy them from materials or from
surfaces.
8
9. How sterilization destroys
microbes?
Alteration of cell
wall or
cytoplasmic
membrane;
Cell wall
maintains the
integrity of cell.
a)
When disrupted
cannot prevent cell
from bursting and
cellular contents leak
out.
9
10. b) Protein denaturing
Functions
of
protein depends on
its specific 3-D
shape.
Various sterilization
methods denature
proteins and as a
result 3-D shape
and their functions
are lost.
10
11. c) Interference with Nucleic Acid
Nucleic Acid
is
considered as
controlling centre
of the cell.
Various methods of
sterilization
methods can
I.
II.
Produce mutation,
Interfere the process
of transcription.
11
12. Sterilization of Dental
Instruments
Spaulding in 1968, classify dental
instruments into three categories
depending on the risk of transmitting
infection.
Critical
Semi critical
Non critical
12
13. CRITICAL INSTRUMENTS
Critical instruments are
those that penetrate soft
tissue, bone or blood
stream.
They have the greatest
risk of transmitting
infection
They should be heat
sterilized between
patient uses.
Examples of critical
instruments include
surgical
instruments,forceps,
scalpels, scalers, and
burs.
13
14.
SEMI CRITICAL
INSTRUMENTS
Semi-critical
instruments are those
that do not penetrate
soft tissues or bone
but contact mucous
membranes
These instruments
should be sterilized or
high-level disinfection
is appropriate.
Examples: Mirrors,
reusable impression
trays and amalgam
condensers etc
14
17. Methods of Sterilization
There are two types
of sterilization:
Microbial
1. Physical
Control
2. Chemical
Methods
Physical Methods
Heat
Radiation
Physical Chemical
Agents
Agents
17
18. Agents used in sterilization
Chemical
agents:
agents:
Dry heat: flaming, 1. Phenols
Moist heat: boiling, 2. Alcohols
steam under
3. Aldehydes
pressure.
4. Gases: ethylene
Radiation
oxide,
Formaldehyde
gas, ozone……
Physical
1.
2.
18
21. MOIST HEAT
Moist heat is more effective than dry
heat because water is good conductor
of heat than air
Mode of action: Denaturing of protein
TYPES
◦ Boiling
◦ Steam under pressure(autoclaving)
21
22. AUTOCLAVING
Invented by Charles Chamberland in
1879
Most economical method of sterilization
Time required at 121 C is 15 mins at 15
lbs of pressure
Main Components of autoclave:
• Consists of vertical or horizontal
cylinder of stainless steel
• Lid , pressure gauge and a safety valve.
22
23. ADVANTAGES
1. Short efficient cycle time.
2. Rapid and effective
3. Ability to process a wide range of
materials
4.Good penetration
23
26. Ionizing radiations:
Ionizing radiation
includes X-Rays
and Gamma rays.
Cause mutations in
DNA and produce
peroxides.
These are
commercially used
for sterilization of
disposable items.
(cold sterilization).
26
27. Nonionizing radiation
Non ionizing
radiation includes
UV light and
Infrared.
Affects 3-D
structure of
Proteins and
nucleic acids.
Suitable for
transparent fluids,
and surfaces of
objects.
27
28. CHEMICAL METHODS
In Chemical methods of Sterilization
we use various chemical agents that
includes,
1) Phenolic compounds
2) Alcohols
3) Aldehydes
4) Gaseous sterilizers
28
29. 1. Phenols and Phenolics:
Phenol
acts
as
protoplasmic
poison, penetrates & disrupts cell
wall and cause bacterial death by
inactivation of essential enzyme
systems.
Used for decontamination of
hospital
laboratory
noncritical
items.
environment
surfaces,
medical
&
including
&
for
surgical
29
30. 2. Alcohols:
Kill bacteria (bactericidal), fungi
and viruses.
Act by denaturing proteins and
disrupting cell membranes.
. Used as skin antiseptic to
wipe microbes off skin before
injections.
Also used for disinfection of
thermometer, probes and
external surfaces of
stethoscope.
30
31. 3. Aldehydes:
Inactivate proteins by
forming covalent cross
links with several
functional groups.
Commonly used
aldehyde is FORMALIN
(37% aqueous solution).
used extensively to
inactivate viruses &
bacteria in vaccines.
Also used to sterilize
metal instruments.
31
32. 4. Gaseous Sterilizers:
Denature proteins, by
replacing functional
groups with alkyl
groups. Also reacts with
DNA & RNA.
These includes
1) Ethylene Oxide
2) Formaldehyde gas
3) Ozone…….
32
34. STERILIZATION MONITORING
There are 3 methods of monitoring
sterilization:
Mechanical techniques
Chemical indicators
Biological indicators
These parameters evaluate both the
sterilization conditions and
procedure’s effectiveness
34
35.
MECHANICAL INDICATORS: Includes
assessing cycle time,temperature and
pressure by observing the displays on the
sterlizers
CHEMICAL INDICATORS: They allow
detection of equipment malfuctioning and
help in identifying procedural errors
BIOLOGICAL INDICATORS: Most
accepted for monitoring sterilization
process
35
