7. Sterilization in Dentistry
Sterilization procedures are very
important to any good dental practice
ď Patients mouth are teeming with
microbes.
ď 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.
ď
7
8. Why we need
Sterilization?
Microorganisms capable of causing
infection are constantly present in the
external environment and on the
human body.
ď Microorganisms are responsible for
contamination and infection.
ď The aim of sterilization is to remove or
destroy them from materials or from
surfaces.
ď
8
9. How sterilization destroys
microbes?
Alteration of cell
wall or
cytoplasmic
membrane;
ďś Cell wall
maintains the
integrity of cell.
a)
ď
When disrupted
cannot prevent cell
from bursting and
cellular contents leak
out.
9
10. b) Protein denaturing
ďś Functions
of
protein depends on
its specific 3-D
shape.
ď Various sterilization
methods denature
proteins and as a
result 3-D shape
and their functions
are lost.
10
11. c) Interference with Nucleic Acid
ďś Nucleic Acid
is
considered as
controlling centre
of the cell.
ď Various methods of
sterilization
methods can
I.
II.
Produce mutation,
Interfere the process
of transcription.
11
12. Sterilization of Dental
Instruments
ď
Spaulding in 1968, classify dental
instruments into three categories
depending on the risk of transmitting
infection.
Critical
ď Semi critical
ď Non critical
ď
12
13. CRITICAL INSTRUMENTS
Critical instruments are
those that penetrate soft
tissue, bone or blood
stream.
ď They have the greatest
risk of transmitting
infection
ď They should be heat
sterilized between
patient uses.
ď Examples of critical
instruments include
surgical
instruments,forceps, scal
pels, scalers, and burs.
ď
13
14. ď
ď
ď
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
ďś Heat
ďś Radiation
Physical Chemical
Agents
Agents
17
18. Agents used in sterilization
ď Physical
agents:
Dry heat:
flaming, Moist
heat:
boiling, steam
under pressure.
2. Radiation
1.
Chemical
agents:
1. Phenols
2. Alcohols
3. Aldehydes
4. Gases: ethylene
oxide, Formalde
hyde
gas, ozoneâŚâŚ
ď
18
20. Dry Heat:
âTo sterilize
Forceps, Scissor
s, Scalpels.â
â˘
Direct Flaming:
Used to sterilize
inoculating loops
and needles. Heat
metal until it has a
red glow.
20
21. MOIST HEAT
ď
Moist heat is more effective than dry
heat because water is good conductor
of heat than air
ď
Mode of action: Denaturing of protein
ď
TYPES
⌠Boiling
⌠Steam under pressure(autoclaving)
21
22. AUTOCLAVING
Invented by Charles Chamberland in
1879
ď Most economical method of sterilization
ď Time required at 121 C is 15 mins at 15
lbs of pressure
ď Main Components of autoclave:
⢠Consists of vertical or horizontal
cylinder of stainless steel
ď
⢠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:
ď Ionizing radiation
includes X-Rays
and Gamma rays.
ď Cause mutations in
DNA and produce
peroxides.
ď These are
commercially used
for sterilization of
disposable items.
(cold sterilization).
26
27. Nonionizing radiation
Non ionizing
radiation includes
ďś UV light and
Infrared.
ďś Affects 3-D
structure of
Proteins and
nucleic acids.
ď Suitable for
transparent
fluids, and surfaces
of objects.
ď
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
ď
28
29. 1. Phenols and Phenolics:
ďś
Phenol
acts
as
protoplasmic
poison, penetrates & disrupts cell
wall and cause bacterial death by
inactivation of essential enzyme
systems.
ďś
Used for decontamination of
hospital
laboratory
noncritical
items.
environment
surfaces,
medical
&
including
&
for
surgical
29
30. 2. Alcohols:
ď
ď
ď
ď
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:
ď
ď
ď
ď
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.
ď These includes
1) Ethylene Oxide
2) Formaldehyde gas
3) OzoneâŚâŚ.
ď
32
34. STERILIZATION MONITORING
ď
There are 3 methods of monitoring
sterilization:
Mechanical techniques
ď Chemical indicators
ď Biological indicators
ď
ď
These parameters evaluate both the
sterilization conditions and
procedureâs effectiveness
34
35. ď
MECHANICAL INDICATORS: Includes
assessing cycle time,temperature and
pressure by observing the displays on the
sterlizers
ď
CHEMICAL INDICATORS: They allow
detection of equipment malfuctioning and
help in identifying procedural errors
ď
BIOLOGICAL INDICATORS: Most
accepted for monitoring sterilization
process
35