Download Current Sterilization Protocols

lin~
-- - Current Sterilization Protocols -
An Orthodontic Perspective
PART I
Orthodontic Implications of Current Sterilization Protocols and
Sterilization induced Instrument Damage
Author's Name:
Dr. Abraham Vinod Korath, M.D.S.
Professor,
Dr. Abra ham Vinod Korath
Department of Orthodontics and Dentofacial Orthopedics
Meenakshi Ammal Dental College and Hospital
Chennai
Dr. Devaki Vijaylakshmi, M.D.S.
Dr. Devaki Vijaylakshm i
Professor,
Department of Orthodontics and Dentofacial Orthopedics
Meenakshi Ammal Dental College and Hospital
Chennai
PART II
Practical Guidelines for Implementing Instrument Sterilization
in the Orthodontic Office
Author's Name:
Dr. Abraham Vinod Korath, M.D.S.
Professor, Department of Orthodontics and Dentofacial Orthopedics
Meenakshi Ammal Dental College and Hospital
Chennai
Dr. Janardhanam P., M.D.S.
Professor, Department of Orthodontics and Dentofacial Orthopedics
Meenakshi Ammal Dental College and Hospital
Chennai
Dr. Janardhanam P
Corresponding Address:
Dr. Abraham Vinod Korath, M.D.S.
Dept. of Orthodontics,
Meenakshi Ammal Dental College and Hospitals,
No.1, Alapakkam Main Road,
Maduravoyal,
Chennai 600 095.
Tamilnadu .
Tel No. : 0-9445098526
E-Mail: docvinodabraham @ya hoo.co.in
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PART I
ORTHODONTIC IMPLICATIONS OF CURRENT STERILIZATION PROTOCOLS AND
STERILIZATION INDUCED INSTRUMENT DAMAGE
Abstract :
Considering the enormity of the challenge that infectious agents pose against us, as well as their
nature to continuously evolve in real time; the implementation and execution of effective infection
control protocols among all health care communities including our own is vital. Against thi s
backdrop; various sterilization protocols are reviewed concomitantly with relevant scientific data
from the orthodontic community as well as outside; evaluating numerous factors deemed critical
from an orthodontic standpoint. It is hoped that these reviews would facilitate the discerning
orthodontist in us to make an informed decision towards their implementation in the orthodontic
office.
Part I of this article focuses on the working principles of various methods of sterilization with an
appraisal of their effects on orthodontic instruments. Additionally, contributory factors of instrument
damage is enumerated to emphasis the importance of adhering to precise protocols and
manufacturer recommendations as well as in alleviating some misconceptions about sterili zation
induced instrument damage.
Keywords:
Orthodontic Instruments, Pliers, Corrosion, Sterilization.
PART II
PRACTICAL GUIDELINES FOR IMPLEMENTING INSTRUMENT STERILIZATION
IN THE ORTHODONTIC OFFICE
Abstract :
Considering the enormity of the challenge that infectious agents pose against us, as well as their
nature to continuously evolve in real time; the implementation and execution of effective infection
control protocols among all health care communities including our own is vital. Against thi s
backdrop; various sterilization protocols are reviewed concomitantly with relevant scientific data
from the orthodontic community as well as outside; evaluating numerous factors deemed critical
from an orthodontic standpoint. It is hoped that these reviews would facilitate the discerning
orthodontist in us to make an informed decision towards their implementation in the orthodontic
office.
Part II of this article offers practical guidelines and recommendations for effective sterilization in
the orthodontic office. These guidelines are additionally suited for easy implementation with the
instruments longevity in mind. Sterilization protocols are recommended for pliers, molar bands,
elastomeric ligatures and chains, impressions and orthodontic appliances. Additionally a
recommended sterilization protocol for the extremely stable group of infectious agents called
prions is highlighted as well as its implication on instruments.
Keywords:
Orthodontic Instruments, Pliers, Corrosion, Sterilization.
INTRODUCTION
to oral surgeons in contractin g infecti ons like hepatitis
in our offi ces. 2, 3 ConSiderin g the enormity of the
challenge that infecti ous agents pose agai nst us, as we ll
as their nature to continuously evolve in rea l time; the
implementation and execution of effecti ve infection
control protocol s among all hea lth ca re comm unities
incl uding our own is vital.
Th need for adequate steri lization cannot be overstressed and we have the informati on age to thank for
that. Although various forms of sterilization have been
impl emented in orthodontic offices, it has bee n
hi ghlighted that most p rotoco ls empl oyed we re
conv enient adaptatio ns t hat faci l ita ted fasterturn around times and orthodontic instrument longevity.
M atlack's review of orthodon ti c offices 'confirmed thi s
insuffi ciency despite the fact that we are second onl y
Aga inst thi s backdrop; an appraisa l of the current
sterili zation protocol s from an orthodontic perspective
is outlined so th at it would fac ilitate the discerning
74
lin~
--orthodontist in us to make an informed decision
towards their implementation. Various methods of
sterilization are reviewed concomitantly with relevant
scientific data from the orthodontic community as well
as outside; evaluating numerous factors deemed critical
from an orthodontic standpoint. Although the focus of
this article is on steri lization protocols pertaining to
orthodontic instruments and materials, it is hoped that
these insights wi ll guide the clinician towards the
understa nding and imp lementation of additiona l
infection contro l measures with the overall office in
mi nd.
PART I
ORTHODONTIC IMPLICATIONS OF CURRENT STERILIZATION PROTOCOLS AND
STERILIZATION INDUCED INSTRUMENT DAMAGE
Steps to Asepsis - From in fected instruments to
complete sterilization
pass of debridement under ru nning water by direct precleaning in speCially designed containers and
cassettes. 5Specia l so lutions have been recommended
in their use; having anti-rust compositions and some
wh ic h are even enzy me based for maximum
effectiveness in the breakdown of contaminants and
particles. Pre-clean ing cycles usually last between 5 15 minutes, depending on the instrument load. An
additional advantage with cleaners is that instruments
such as pliers and orthodontic bands can be placed at
the onset of the process itself in specially designed
cassettes to reduce the like lihood of instrumental
damage without a compromise on the quality of
steri li zation ach ieved .
Sterilization refers to any process that effectively ki lls
or eliminates transmissible agents from a surface,
equipment, article of food or medication, or biologica l
culture medium. Sterilization can be achieved through
the application of heat, chemica ls, irradiation, high
pressure or filtration. Oisinfectionmay be defined as
cleaning an article of some or all of the pathogenic
organisms which may cause infection. Disinfectants
are anti microbial agents that are applied to non-living
objects to destroy micro-organ isms.
The Advice sheet issued for Infection contro l in
Dentistry issued, from the Department of Hea lth, United
Kingdom enumerates three stages to sterilization or the
decontamination process namely; Pre-sterilization
cleaning, Sterilization and Storage. 4 The various
protocols and methods employed for decontami nation
of instruments including steri lization are outlined
primarily from an orthodontic perspective.
•
On a fina l note regardi ng the pre-cleaning stage, an
important point to remember is that irrespective of the
manner in which pre-cleaning is done, it is crucial
that any traces of residua l moisture is eliminated
through appropriate drying measures (compressed air)
the actua l sterilization process. The presence of
moisture espeCially between the joints and tips
(serrated) of instruments increases the corrosive
tendency in instruments, especia ll y when fol lowed by
certain methods of steril ization.
Pre-sterili zation Cleaning
All instruments must be thoroughly c l eaned
(debrided)of contaminants (blood, saliva and other
impurities)before undergOing a sterilization cycle; as
the retention of these contami nants and debris may
shield the organisms from the sterilization protoco l
intended to kill them. Pre-cleaning protoco ls remove a
large number of organisms when carried out thoroughly
and present day automated equipments are very
effective.
•
Sterilization - Common Types, M echanism of
Action and Orthodontic considerations
The decis ion to i mp lement the right steri lization
protoco l depends not onl y on the anti -microbial
effectiveness but also on factors involving turnaround
times w hich determine the requirement of prior presteri lization, additional inventory and the effects of
these protocols on instruments. The working princip les
of cu rrently recom mended protoco ls in genera l wi II
be outlined to highlight their efficacy as wel l as
shortcomings when it comes to our orthodontic needs.
Protocols' involving pre-cleaning have conventiona lly
involved initial debridement of all instruments By Hand
aided by a brush and detergent under running water.
Though cost-effective, the hand cleaning process not
only poses a risk to the personnel but is also time
consuming. Present day protocols invo lve the use of
Autoclaving or Steam under Pressure Sterilization
Ultrasonic baths and Instrument Washer / Oisinfectors
•
pre-cleaning of hand instruments. They enable the by75
Effective against all fungi, bacteria, viruses and
spores
•
Current OSHA and EPA guidelines for manufacturers
necessitate improvements in the metallurgical
properties to offset the effects of repeated cycles and
exposure to heat; the Prestige Series (3M Unitek) of
pli ~rs is a step in this direction.
Causes rusting and corrosion of instruments
Autoclaving is the gold standard for effective
sterilization and is employed for most surgical needs.
This process subjects instruments to steam
condensation under pressure (15 psi) at a temperature
of 12 1°C to 134°C (250°F - 273°F). To achieve
sterilization, a holding time of atleast 15 minutes at
121 °C (Conventionan or 3 minutes at 134°C (Rapid
cycle) is required. Following sterilization, a cooling
down period is usually required. A complete cycle from
start to sterilization and subsequent cool down ranges
from 40 minutes to 1 hour for Rapid and Conventional
Cycles. This is an important consideration where a faster
instrument turnaround is required.
In general, higher temperatures associated with this
process can predispose to some changes in the physical
properties of the plier and manufacturers caution
against instrument exposures above 380°F (193°C).
Long-term effects of repeated dry-heat sterilization have
reported minimal changes in the physical
characteristics of orthodontic pliers where corrosion
and micro-hardness were evaluated.
Chemical Vapor Sterilization or Chemic/ave
An important feature of autoclaves is that they are
equipped with an indicator that records and displays
the temperature and pressure involved in the process,
as a function of time. This enab les a verification of the
effectiveness of the process.
Although extremely effective as a form of sterilization,
the presence of steam vapor in the process has been
found to be detrimental for orthodontic pliers.
Com parative studies on the various sterilization
protocols have reported the occurrence of corrosive
changes with repeated cycles. 6 Corrosive changes were
found to occur around hinge areas, sharp angles, cutting
edges or pointed ends that facilitated the retention of
water vapor.
Effective against all fungi, bacteria, viruses and
spores.
•
Best suited for orthodo ntic needs due to the
absence of moisture.
•
Repeated Heat cycles can alter surface hardness
characteristics of instruments
Effective against all fungi, bacteria, viruses and
spores.
•
Preserves instrument integrity but causes dulling
•
Not a practical option in dental offices
Chemical vapor steri Iization is carried out at a pressure
of 20 psi and temperature of 132°C (1270 OF); with a
solution of various alcohols, acetone, ketone,
formaldehyde (0.23%) and distilled water (9.25%). The
sterilization time is 20 minutes exclusive of pressure
rise time. By principle, this process substitutes the water
vapor for chemical vapor on autoclaving.
It is considered as the safest process as it does not
compromise on the cutting efficiency of instruments
even though dulling is seen with long-term use. Some
instrument manufacturers do not recommend them
because of this observation.
Dry Heat and Rapid Dry Heat Sterilization Process.
•
•
Although advantageous from an orthodontist's
perspective it has not gained popularity due to the
presence of a strong odor necessitating separate
enclosures with adequate ventilation. Present day
chemiclaves meet or exceed OSHA emission standards
as they are equipped with a built in chemi-purge and
chemi -filter to slash emissions.
Dry Heat sterilization causes oxidative destruction of
bacterial protoplasm at a temperature range of 160°C
(320°F) and initially involved duration of up to 2 hours
to achieve comp lete sterilization. Present day hot-a ir
steri li zation involve cycles at temperatures of 190°C
(375°F) for 6 to 12 minutes and is known as Rapid
Dry-Heat Sterilization. Instruments must be dry before
sterili zation, as the presence of water will interfere with
the process. Additionally, the higher temperature
involved with the process warrants a longer cool-down
time. The absence of moisture in the sterili zatio n
process is beneficial to the longevity of orthodontics
pliers, the cutting surfaces; thereby making it
advantageous over other steri lization protocols. 7• 10
Chemical Immersion or Cold Sterilization
•
Recommended only for heat-sensitive non surgical instruments and alginate impressions
•
Prolonged immersion time required for
effectiveness
•
No method to verify effective sterilization
•
Predisposes to Pitting type corrosion in orthodontic
instruments
2% acidic glutaraldehyde (Banic ide) and chlorine
76
dioxide are commonly used sterilants which are ADAapproved. The instruments to be sterilized are immersed
in solution according to manufacturer's instruction for
a specific duration to enable effectiveness. Sterilization
time with 2% acidic glutaraldehyde is 10 hours without
dilution and with chlorine dioxide (Exspor 4:1:1) is
6 hourswhen mixed according to the manufacturer's
instructions.
temperature ranges against most manufacturer warnings
(3 80 ° F/193 ° C). protocol involving molar band
sterilization reported spore effectiveness at 226°after
45 seconds for a single band. n Additional numbers will
concomitantly increase this time duration with a strong
possibility of altering the physical characteristic of the
band .
The impracticality of cold sterilization methods lies with
the fact that there is no method to verify their action
despite the longer duration required; as a result, present
day protocols are co mbined with heat sterilization as
they are the only acceptable means of reprocessing.
Sterilization Induced Instrument Damage Contributory Factors and Misconceptions
Most of us associate the protocol of sterilization with
instrument damage. How did an integrity preserving
protocol end up as its main violator?
Studies comparing the effects of cold sterilization with
other sterilization protocols revealed that it predisposes
to a pitting type of corrosion which is more deleterious
than surface corrosion as it denotes a severe
compro mise in the integrity of the instrument.l1 ,
12 Ligature Cutters examined through SEM revealed the
presence of micro-cracks. Fe-Cr alloys were more prone
to corros ion than Cr-Co alloys. Loosening of tungsten
carbi de tips and loss of gold plating have also been
reported due to prolonged immersion.
Listed below are some of the known contributory factors
which either independently or in combination can
cause or accelerate corrosion and damage to
instruments. The factors enumerated are intended to
highlight as well as alleviate misconceptions about
steri I ization.
1. Water Quality: pH imbalances and harmful, higher
mineral content are known to cause co rrosion in
instruments.
If there is an orthodontic recommendation for this form
of sterilization then it would be for disinfecting alginate
impressions with the precaution that the immersion
time be limited to 10 minutes to preserve dimensional
and surface integrity. Research is presently directed at
comb ining these agents with alginate impression
materials enabling a low ph having anti-viral activity
agai nst the herpes simplex virus which additionally
releases nitric oxide, a broad spectrum antimicrobial
agent. 21
2. Strong Detergents: Promote the precipitation of
proteins on instruments which can be difficult to
remove and in turn act as local foci from where
corrosion can be initiated in the presence of other
promoters of corrosion.
3. Excessive Heat Exposure : An increased temperature
exposure
above
current
manufacturer
recommendation of 380°F (193°C) is not advisable.
Please note that this is only for the newer generation
of pliers manufactured to meet the demands of
current recommended sterilization protocols
involving dry-heat sterilizers; Older and cheaper
quality pliers would not even qual ify for this method
of steri I ization.
Glass Bead Sterilization
•
Use limited to orthodontic bands
•
Higher temperatures can be deleterious for
orthodontic plier tips.
4. Presence of moisture: Improper drying following
pre-cleaning in pliers and instruments during
sterilization is one of the most important factors for
corrosion. All instruments must be thoroughly dried
prior to dry heat sterilization. Moisture centric
protocols like autoclaving are deleterious and not
recommended for sterilization of instruments.
Glass bead sterilization uses small glass beads ranging
from 1.2 to 1.5mm in diameter. The suggested heating
range is 424°F to 450°F (217°C to 232 °C) for 3 to 5
seco nds but not exceeding 482 ° F (250°C). A
relationship exists between the size and working surface
of an instrument an d the temperatures attained in the
bead sterilizer. The larger the instrument, the longer
the heat-up time required .
5. Chemical Immersion or Cold sterilization :
Instruments sterilized through this process are
reported to be associated with pitting type corrosion
which can be very damaging.
Although the possibility of being able to sterilize 1 to 2
orthodontic pliers within 30 seconds has been
highlighted with a stress on correct positioning for
maximum effectiveness; 14 these recommendations are
deleterious as the instruments are exposed to higher
6. Disinfectant Compositions: Chemical sol utions and
Enzymatic cleaning solutions are presently not
recommended due to their corrosive effects.
77
8. Damaged instruments : Sterilization accelerates
corrosion in instruments which already have
compromised physical characteristics and surface
irregu larities.
7. Cheap quality pliers : Cheaper pliers generally
connote poor alloying elements and additional ly
poor milling qualities, which are attributes
conducive to corrosion.
PART II:
PRACTICAL GUIDELINES FOR IMPLEMENTING INSTRUMENT STERILIZATION
IN THE ORTHODONTIC OFFICE
Th e recommended guidelines for orthodontic
sterilization requirements are outlined for maximum
effectiveness while preserving instrument integrity.
Guidelines for Steri lization of Orthodontic Pliers:1. U ltrasonic cycle for 5 to 12 minutes depending on
the capacity of the unit.
A planned and designated area within the clinic setting
would facilitate a sequenced and scheduled
sterilization protocol where pre-allotted disinfection
and storage areas will demarcate as well as segregate
the contaminated from the sterilized and ready to use
instruments.
2. Rinsing with Distilled Water.
3. Remove excess moisture thorough drying with
Compressed Air (Oil-Free).
4. Lubrication of plier joints and cutting surfaces with
si li cone based lubricants.
Additionally, it is emphasized that the use of water for
rinsing of instruments when required be carried out
from sources that are free of contaminants and of the
highest filtered quality (RO Systems). Drying protocols
involving compressed air must be from oil-free sources.
5. Sterilization protocol using a Dry-Heat Sterilizer at
190°(375°) for 6 to 12 minutes with the placement
of pliers in an open.
6. Storage.
The recommendation of a final rinse with Distilled water
following any pre-cleaning protocol is recommended
to offset the impurities present in tap water as well as
the possibility of ionic imbalances present with
automated cleaning solutions. Additionally silicone
based lubricating sprays can be used for pliers before
the dry-heat process and also after if the instrument is
to be stored. Oil-based lubricants are not recommended
as they tend to clog the pliers.
The following equipments are deemed as essential
requirements for implementing and maintaining
effective infection control standards in your orthodontic
office:1.
Ultrasonic Unit (for debridement and precleaning protocols)
2.
Dry-Heat Steri lizer
3.
Desktop Autoclave Sterilizer
Autoclaving is recommended only if a dry heat sterilizer
is not avai lable and only as a secondary option to dry
heat sterilization. A shorter cycle at 1340for 3 minutes
is recommended due to the detrimental nature of the
process on instruments. Instruments must be wrapped
prior to the process after ensuring complete absence
of moisture in the instrument.
Th e suggested list is recommended for all primary
instrument sterilization protocols. Secondary protocol
involving chemical disinfectants as well as alcohol
based wipes is recommended only for instruments and
materi als which do not come into direct contact with
th e pati ent and where cross contamination risks are
not involved.
Orthodontic Plier Sterilization
Prion protection - Sterilization protocol for
Orthodontic pliers
The steri lization protocols employed for orthodontic
pli ers have been reported to affect the physical and
mechani cal characteristics. Enumerated below are
current recommendations with effectiveness against
organisms as well as the longevity of the instrument in
mind .
Prions are an extremely stable group of infectious agents
that are resistant to conventional sterilization protocols.
They are composed primarily of protein and are
hypothesized to infect and propagate by refolding
abnorma lly into a structure. Then, this converts normal
molecules of the protein into an abnormally structured
78
form. This altered structure is extremely stable making
it resistant to destruction by chemical and physical
agents conventionally employed.
sterilization cycle. Pre-formed bands having welded
counterparts are not recommended for autoclaving.
It is recommended that chemical immersion protocols
be limited to bands without pre-welded attachments if
conditions necessitate its use. Longer time duration
required as well as the lack of any indicator for its
effectiveness makes it a less than secondary choice for
sterilization .
For Prion elimination , recommendations have
advocated autoclave cycles at 12 f for 60 minutes or
134ofor at least 18 minutes or combination cycles
involving hot-air sterilization followed by autoclaving
to improve the margin of the safety. The effects of such
extreme Prion sterilization protocols on orthodontic
pliers were evaluated recently were ligature cutters
were sterilized through a protocol involving disinfection
followed by a water disinfector, hot air drying and
finally autoclaving at 134° for 20 minutes followed by
a cooling period of 1 hour. The study observed that
surface alterations occurred from the first cycle itself
with a blunting of the cutting edges and a resultant
decrease in their cutting efficiency.1 s
Elastomeric Ligatures and Chains
Current guidelines for elastomeric and elastomeric
ligatures
•
Elastomerics and elastomeric Iigatures are not suited
for chemical disinfection as they are known to alter
the phYSical characteristics 18, 19. Alcohol wipes are
not an alternative as they are not effective in the
presence of tissue proteins seen in blood and saliva .
Molar Bands
•
Molar bands are one of the most overlooked materials
in the orthodontic armamentarium. The sterilization
of tried-in pre-formed bands has received attention of
late and numerous protocols are rife in orthodontic
literature. 16, 17
Single patient packs are the best insurance against
cross-contamination risks at present and where this is
not feasible as in the case of e-chain spools, it is better
to cut a little extra than required and discard the rest.
Alginate Impression and Orthodontic Appliances
Common disinfecting solutions that are used for
alginate materials include 1 % sodium hypochlorite,
sodium dichloroisocyanurate and 2% glutaraldehyde. 20
Present recommendations involve the immersion of
alginate impressions for not more than 10 minutes in
disinfecting solutions as alterations in surface
characteristics have been observed with prolonged
immersions. 2o
Enumerated below are our recommendations for
sterilization of Pre-formed orthodontic bands for both
the in-received state as well as tried- in ones.
Guidelines for Sterilization of Molar Bands:1. Ultrasonic cycle for 5 minutes depending on the
capacity of the unit.
2. Rinsing with Distilled Water.
Guidelines for sterilization of alginate impressions:-
3. Remove excess moisture thorough drying with
Compressed Air (Oil-Free).
1. Rinse thoroughly under running water following
removal.
4. Sterilization protocol using a Dry-Heat Sterilizer at
190°C (375°) for 6 minutes.
2. Immersions of impression in disinfectant for 10
minutes. Spraying aerosols are not recommended
for their unevenness and additional inhalation risk.
5. Storage.
A recommendation for tried in bands is to process them
through an ultrasonic cycle and store them in separate
containers if they cannot be sterilized immediately.
Additionally while sterilizing these bands it is important
to ensure that they are processed separately from the
in-received bands.
3. Rinse again under running water.
Autoclaving of preformed molars bands can also be
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4. Ready for model processing.
Following this the impression can be processed for
model fabrication. Additionally this recommendation
is suited for orthodontic appliances as well.
carried out as an alternative to dry heat sterilization as
the smooth surface of the band does not leave any
scope for moisture retention; and additionally because
they can be wrapped and marked if both in-received
and tried-in bands are to be sterilized in the same
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