Evaluation of various /certified fixed orthodontic courses by Indian dental academy

“EVALUATION OF VARIOUS
STERILIZATION PROCESSES OF
ORTHODONTIC INSTRUMENTS USING
BIOLOGICAL INDICATORS AND
CONVENTIONAL SWAB TEST METHOD”
-A COMPARATIVE STUDY

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

INTRODUCTION


• With the introduction of implants and
Orthognathic Surgery, and its growing
popularity the necessity for sterilization
has increased manifold.
• It has been found that Orthodontists have
second highest incidence of Hepatitis B
among Dental professionals.


•

Most commonly used Infection Control
methods are:

1. Disinfection.
2. Sterilization.
•

Disinfection reduces microbial contamination
but is generally less lethal to pathogenic
organisms than sterilization and does not
remove all the vegetative spores.

•

Sterilization destroys all forms of
microorganisms including viruses, bacteria,
fungi, and spores.

•
1.

How much effective or efficient is the sterilization
procedure can be monitored by using:Chemical Indicators.

2.

Lab culture method.

3.

Biological Indicators.

•

Most frequently used method for checking the
effectiveness of sterilization is the Chemical
Indicators. They are available in form of strips.

•

Their drawback is they only assure that the
instruments have been exposed to sterilization cycle;
they don't verify that complete sterilization has
occurred and all vegetation has been destroyed.

• Conventional microbiological culture method can
determine the effectiveness of sterilization process by
spore growth which can be seen by naked eye.
• Drawback of this procedure is that it requires lots of skill
to determine the spore growth, even air borne
contamination can affect the result of the culture method.
And about 48 to 72 hours for spores to grow on culture
medium.
• Biological Indicators have been stated that they can
provide a better method of verifying the effectiveness of
sterilization procedures.

• Biological Indicators consist of ampules or strips
enclosed in glassine envelope that contain a known
quantity of Bacillus Stearothermophilus and /or
Bacillus Subtilis spores.

• Biological Indicators for monitoring Steam Autoclave
or Chemical Vapor sterilization contain spores of
Bacillus Stearothermophilus (Geobacillus
Stearothermophilus).

• Biological Indicators for monitoring Dry Heat or
Ethylene Oxide sterilization contain spores of
Bacillus Subtilis (Bacillus Atrophaeus).

Aims And Objectives:


1. Comparative evaluation of control and experimental groups by
sterilization of orthodontic instruments using:
– Autoclave sterilizer
– Hot air oven sterilizer
– Ethylene oxide sterilizer
•
•

Control Group: The contaminated instruments were ultrasonically
cleaned and air dried but was not processed through different
sterilization procedures.
Experimental Group: The contaminated instruments were
ultrasonically cleaned and air dried and was processed through
different sterilization procedures.

2. To compare the efficiency of various sterilization procedures using
conventional spore monitoring method i.e. by using swab test and
biological indicators.
3. To determine the efficiency of Cold Sterilization by using Bioclenz-G
(2% Glutaraldehyde) solution.

REVIEW OF LITERATURE


•

In 1857 Pasteur Louis introduced techniques of sterilization and
developed the steam sterilizer, Hot-Air Oven and Autoclave.

•

Council on Dental Therapeutics (1973) accepted Glutaraldehyde
(cidex) as a disinfecting and sterilizing agent.

•

Matis B., Sellers R., and Christen A.(1980) did a study to
determine permeability of protective covering of Biological spore
monitor to formaldehyde. It was recommended that chemical vapor
sterilizer should be avoided with layering of packages of
instruments.

•

Skaug N (1983) did a survey to determine the sterilization
procedures used by Oral Surgeons in Norway. The instruments
were sterilized using Steam Autoclave at 1210C or 1340C; and Dry
Heat Oven sterilizer. The sterilization procedures were monitored
using Biological Indicators.

•

Field E.A., Field J.K., Martin M.V.(1988) conducted a study to test
the physical effectiveness of TST (Time, Steam, and Temperature)
strips for monitoring autoclave sterilization.

•

Miller C.H., Sheldrake M.A. (1990) performed a study to compare
immediate and delayed incubation on the ability of Biological
Indicators to detect sterilization failures.
The result showed that appropriate Biological Indicator can detect
sterilization failure after immediate and after delayed incubation of
seven days.

•

Hohit William F., Miller Chris H., Neeb M John., Sheldrake A.
Margle (1990) performed a study to determine whether Orthodontic
instruments and bands contaminated with blood or saliva and
bacterial spores can be sterilized by Steam, Chemical Vapor, or
Dry-Heat sterilizer. All the three types of sterilization was equally
effective.

•

Hastreiter J. Richard et. al (1991) Suggested that Biological
Indicators were useful in monitoring sterilization performance only
when sterilization procedures are performed consistently and
competently by well trained staff using adequately maintained
instruments.

•

•
•

Palenik C.J.,Burke F.J.T, Coulter W.A., Cheung S.W. (1999)
emphasized the importance of improving and monitoring autoclave
performance.
According to authors Biological monitors are the main guarantee of
sterilization for two reasons:
They can simultaneously monitor the interaction of all sterilization
parameters (temperature, pressure, time) which no gauge,
thermocouple or chemical monitor can accomplish.
They can measure the sterilization process within an individual
pack, tray, or instrument grouping.
The reason for failure of Biological Indicators was related to
human error, such as improper wrapping and /or loading of an
Autoclave.


MATERIALS AND METHODS


Uniclave Mini Autoclave
Hot Air Oven

Ultra Sonic Cleaner

Ethylene Oxide Sterilizer

Incubator

Sets of Hinged & Non Hinged
Instruments

Armamentarium

Biological Indicator Strips


Biological Indicator Ampules

METHODS

Instrument Contamination of Experimental Group

Instruments Precleaning


• One set was not passed through sterilization
process and was directly send to microbiology
lab for culture test which comprised the Control
Group.
• The other set of instruments were passed
through different sterilization cycles which
comprised the Experimental Group.
• Each group was divided into Medium load
(containing 15 sets of instruments) and Heavy
load(containting 30 sets of instruments).
• Each group was tested 15 times each for
medium and heavy load.

Control Group Procedure

Instrument Contamination

Precleaning

Swab


METHOD USED FOR STERILIZATION USING STEAM AUTOCLAVE


Crushing of Ampules

During Incubation

• The crushed ampule was kept inside the incubator along with crushed control
Biological Indicator at temperature of 560C for 24 hours

STEAM AUTOCLAVE SWAB PROCEDURE

• After the sterilization cycle swab of Experimental Group of instruments was taken
along with swab of Control Group of instruments and was processed for Lab
Culture.

METHOD USED FOR STERILIZATION USING ETHYLENE OXIDE
STERILIZER

• The sterilization cycle of Ethylene Oxide sterilizer was 8 hours at 550C

Crushing of Ampules

During Incubation

• Biological Indicator was crushed along with Control Biological Indicator
and was incubated for 24 hours at temperature of 370C

Ethylene Oxide Swab Procedure

• After the sterilization cycle swab of Experimental Group of instruments was
.
taken along with swab of Control Group of instruments and was processed for
Lab Culture.

METHOD USED FOR STERILIZATION USING
HOT AIR OVEN

• Sterilization cycle for Hot Air Oven was 1710C for one hour.
•The spore strips were incubated in Soyabean Casen Digestive Culture Medium at 370C
for one week.

HOT AIR OVEN SWAB PROCEDURE

• After the sterilization cycle swab of Experimental Group of instruments was
taken along with swab of Control Group of instruments and was processed for
Lab Culture.

METHOD USED FOR COLD STERILIZATION

•Biological Indicators are not available for Cold Sterilization, no Indicators were used.
•Swab of Experimental Group & Control Group of instruments was taken for determining
the spore growth.

LABORATORY PROCEDURE

Incubation of Culture Medium
Heating of Platinum Loop

Inoculation of Platinum loop

Steraking of Control Group

Steraking of Experimental Group

After Streak Method

During Incubation

AFTER INCUBATION OF BIOLOGICAL INDICATORS

• After 24 hours of incubation both the Biological Indicators (Control and
Experimental Group) were removed from the incubator and was checked
for change in colour of culture medium. If culture medium changes color it
indicates presence of spores or sterilization failure. If there is no change in
colour, it indicates no spore growth and sterilization was proper.

AFTER INCUBATION OF SPORE STRIPS

Before Incubation

After Incubation

• After one week of incubation of spore strip for Hot Air Oven sterilizer change in
turbidity of the culture medium was checked in both Control and Experimental
Group. If the culture medium becomes turbid it indicates sterilization failure. No
change in turbidity indicates proper sterilization.

AFTER INCUBATION OF AGAR MEDIUM

Steam Autoclave

Ethylene Oxide

Hot Air Oven

• After 48 hours of incubation of Agar medium, spore growth was determined.
• The spore growth can be seen with the naked eyes

AFTER INCUBATION OF AGAR MEDIUM

10 minutes

10 hours
Cold Sterilization

• After 48 hours of incubation of Agar medium, spore growth was determined.
• The spore growth can be seen with the naked eyes

GROWTH FOUND IN THREE EXPERIMENTAL GROUP


RESULT


•

Comparative evaluation of Conventional Laboratory Method
with Biological Indicators
Method

• One group out of
fifteen groups in
Steam Autoclave
showed spore growth
in heavy load

• In Dry Heat
sterilization one group
both in medium load
and heavy load showed
spore growth from all
the fifteen groups

of

Monitoring
Sterilization
Procedure

Load

Conventional
Laboratory Method

Biological
Indicator Method

Number
of
Samples
(n)

Dry Heat
Oven

Ethylene
Oxide

Spore
Absent

Spore
Present

Spore
Absent

Medium
Load

0

15

0

15

15

Heavy
Load

Steam
Autoclave

Spore
Present

1

14

0

15

15

Medium
Load

1

14

0

15

15

Heavy
Load

1

14

0

15

15

Medium
Load

0

15

0

15

15

Heavy
Load

0

15

0

15

15


• Evaluation of spore growth in Cold sterilization by Conventional
Laboratory Method

Monitoring
Method
Conventional Laboratory

Method

Time Duration
Spore
Present

10 Minutes
15

10 Hours

0

Spore
Absent
0

Number
of
Samples
(n)

15

15

15

15

• Instruments dipped in Bioclenz-G solution for 10 minutes of cycle showed
spore growth .Whereas instruments dipped for 10 hours of cycle showed no
spore growth.

GRAPH I

Comparison of Conventional Lab Method with Biological Indicators
15 15
No. of groups free of
spores

15

15
14

15
14

15

15 15

15 15

14

10
5
0
Medium Heavy Medium Heavy Medium Heavy
Steam Sterilizer

Dry Heat
Sterilizer

Ethylene Oxide
Sterilzer

Experimental Group
of conventional lab
method
Experimental Group
of Biological
Indicators

• Spore growth was seen in three of the groups tested by Conventional Lab
Method, in comparison with no spore growth in groups tested by Biological
Indicators in Steam ,Dry Heat & Ethylene Oxide sterilization.

GRAPH II
Number of Groups Free of Spores by Cold Sterlization

15

15

16
14
12
10
No. of Grs. Free of
8
Spores
6

Spores Present
Spores Absent

4
2

0

0

0
10 Minutes

10 Hrs.

Time duration

• Spores were present in all the groups tested for 10 minutes cycle,
in comparison to no spore growth in any of the groups tested for 10
hour cycle.

DISCUSSION


•

The study showed that all spores were killed when sterilization process was
monitored by Biological Indicators, but Conventional Swab Test showed spore
growth in three experimental groups- One in Steam Autoclave and two in Hot Air
Oven. This could probably due to Air Borne contamination or contamination of
Swab and Culture while transferring.

•

Instruments dipped in Bioclenz-G solution for 10 minutes of cycle showed spore
growth, whereas instruments dipped for 10 hours of cycle showed no spore
growth.

•

Biological Indicators can be considered as the reliable method to check the
sterilization efficiency as the spores present on them are highly resistant and the
inactivation of the spores determines the sterilization efficiency.

•

Bioclenz-G solution (2%Glutaraldehyde) can be used for sterilization if
instruments are dipped in the solution for 10 hours.

•

Just by Ultrasonically cleaning the instruments sterilization cannot be achieved.
The debris, saliva, and blood may be cleaned and not visible to naked eye. But it
does not ensure eradicating all microorganisms not visible to naked eye as can
be seen by 100% spore growth of instruments of control group.

•

The disadvantage of Biological Indicators or its limitations is that it is not
available to check or monitor all types of sterilization procedures.

CONCLUSION


1.

All methods of sterilization showed complete sterilization of
instruments when monitored with Biological Indicators.

2.

One group of heavy load in Steam Autoclave and one group each
of medium load and heavy load in Hot Air Oven sterilizer showed
sterilization failure when monitored with Conventional Swab Test
Method.

3.

The efficiency of Conventional Swab Test Method in monitoring
sterilization is questionable as the results can vary due to Air
Borne Contamination and Human Error.

4.

The Biological Indicator is the more reliable and accurate method
for monitoring sterilization.

5.

American Dental Association recommends weekly spore testing
of dental office sterilizer to determine the sterilization efficiency.

Evaluation of various /certified fixed orthodontic courses by Indian dental academy

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Evaluation of various /certified fixed orthodontic courses by Indian dental academy