1. 1

2. Sterilization in Dentistry
Presented by;M. Humayun
Afridi
Assisted By; Taif Ahmad And
Saqib Habib
Khyber College Of Dentistry
Peshawar
2

3. STERILIZATION IN
DENTISTRY
3

4. OBJECTIVE

At the end of the presentation the 2nd
year BDS students will know all about
the sterilization.
4

5. Contents
Definition
 Introduction
 Need of sterilization
 Classification of Instruments
 Methods of sterilization
 Sterilization monitoring

5

6. What is Sterilization?

DEFINITION
“Sterilization is the process by
which all forms of microbial life
from surface,medium and
instruments are destroyed by
various physical and chemical
methods”
6

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, scal
pels, 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

15. NON CRITICAL INSTRUMENTS



Non-critical
instruments are
those that come in
contact with intact
skin.
Risk of transmission
of infection is
minimum.
Examples:X-ray
heads,pulse
oximeter,BP cuff
,dental chair etc.
15

16. DENTAL
CHAIR
16

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
 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, ozone……

18

19. Physical
Agents
Heat
Dry
Direct Flaming
Radiation
Moist
Steam Under
Pressure
(autoclaving)
Ionizing
X
Ray, Cathode,
Gamma
Non Ionizing
UV
19

20. Dry Heat:
“To sterilize
Forceps, Scissor
s, Scalpels.”
•
Direct Flaming:
Used to sterilize
inoculating loops
and needles. Heat
metal until it has a
red glow.
20

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

24. AUTOCLAVE
24

25. RADIATION

1.
2.
There are mainly two types of
Radiations used in dentistry.
Ionizing radiation
Non Ionizing radiation.
25

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

33. Methods of Sterilization
Heat
Chemicals
Sterilization
Radiation
Gases
33

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

36. References
Wikipedia
 SS Hiremath
 Google Images
 Slide share

36

37. 37