STERILIZATION IN ORTHODONTICS

CONTENTS• INTRODUCTION• HISTORY• MODES OF TRANSMISSION• INFECTION CONTROL IN CLINICAL AREA• STERILIZATION• METHODS OF STERILIZATION• MONITORING STERILIZATION• DISINFECTION• CORROSION OF INSTRUMENTS

For protection of both the doctor and patient, sterilization techniques are of utmost importance in preventing the spread of infectious disease. This is of special significance in dentistry because more microorganisms are found in the oral cavity. With the increasing number of adult patients and diverse life-styles, the orthodontist is more at risk than ever to exposure to serious pathogens and must take precautions to guard against their transfer.  

INTRODUCTION

HISTORY Ignaz Semmeiweiss-Hungarian

obstetrician

William Henry- a Manchester physician

Sir Joseph Lister-  "father of modern surgery"

MODES OF TRANSMISSION

•FROM PATIENT TO PRACTITONER.•FROM PRACTITONER TO PATIENT.•FROM ONE PATIENT TO ANOTHER(CROSS INFECTION).

INFECTION CONTROL IN THE CLINICAL AREA

•PERSONAL PROTECTION EQUIPMENTS(PPE).

•ENVIRONMENTAL SURFACE CLEANING &

DISINFECTION

•INSTRUMENT STERILIZATION.

•DISPOSAL OF WASTE.

PERSONNEL PROTECTION EQUIPMENT (PPE)

•Protective clothing.•Gloves.•Masks.•Protective eyewear.

PROTECTIVE CLOTHING

Protect worker from exposure to contaminated materials.

GLOVES

Gloves should be used while touching

1. Blood and body fluids.

2. Mucous membrane.

3. Non intact skin of the patient.

4. Items or surfaces soiled with

blood or body fluids.

General precautions while using gloves

• Wear gloves for all dental procedures

• Discard gloves whenever they have been contaminated.

• Do not leave the clinic or walk around wearing gloves.

• Wash hands after removing gloves.

REPROCESSING OF GLOVES• Rinse your gloved hands thoroughly in a hypochlorite

solution.• Then in clear water to remove the disinfectant.• Wash with soap and water and rinse thoroughly.• Remove the gloves and hang them up by the cuffs to dry• Dust glove powder on the inside of the gloves .• Test for holes in the gloves before reuse.• Autoclave the gloves.

MASK

• Surgical masks must be worn to protect the face.

• Should have at least 95% filtration efficiency for particles 3-5 micrometer in diameter.

• Should be changed for each patient since its efficiency decreases as it traps

moisture during dental procedures.

EYE PROTECTION• The eyes of a dental professional are

particularly susceptible to physical &

microbial injury by virtue of their

limited vascularity and diminished

immune capacities.

• Eyes must be protected during operative

procedures by spectacles.

HAND WASHING

•First scrub hands with warm water.

•Get soap under the nails and clean

with brush.

•Rinse hands with cold water.

•Wipe hands with paper towel or

dry with warm air.

Sterilization?

The ideal regimen for sterilization

• PREPARATION FOR STERILIZATION

RINSING

DEBRIDMENT

DRYING

RINSING OF INSTRUMENTS

SOAPSDETERGENTS

ALDEHYDES

PHENOLS

proteins and other polymolecular structures, particularly when dry, serve as a protective covering for microorganisms and prevent penetration of sterilizing medium.

Lawrence and Block (1968)

• scrubbing by hand usually with a stiff wire brush.• ultrasonic cleaning devices.

Rubbo and Gardner (1965)

ultrasonic devices act by converting electrical energy vibratory sound waves, which pass through a soap solution containing the instruments.

PRINCIPLES OF STERILIZATION• All used instruments should be thoroughly cleaned and all deposits of blood and debris should be removed before sterilization.

• It is essential for the sterilizing agent (heat, steam and/ or gas) to be in contact with every surface of each item to be sterilized for the specified period of time at the specified temperature.

• All sterilizing equipment must be regularly serviced and maintained by suitably qualified engineers. 

• The manufacturer’s instructions should be strictly adhered to for it’s operation and maintenance.

METHODS OF STERILIZATIONThe ADA Council on Dental Materials recommends that metals

and heat stable instruments undergo sterilization by either

• Autoclave(moist heat)• Chemical vapor (chemiclaving)• Dry heat sterilization (hot air oven)

AJO 1994 December Youngblade,Meyers,andHondrum

• Dry heat and/or Metal items. Autoclaving

• Cold solutions Gas sterilization Non-metal items.

AJO 1993 Staggers Margeson

AUTOCLAVE (MOIST HEAT)

-The results are consistently good -the instruments can be wrapped prior to sterilization

-Blunting and corrosion of sharp instruments.-Damage to certain rubber goods.

3 FACTORS

PRESSURE TEMPERATURE TIME

STERILIZATION CYCLE

Temperature

Time

Pressure

Unwrapped instruments 134oc 3 min 30 psi

Wrapped instruments 1210c 15-20

min15 psi

AUTOCLAVE

SMALL BENCH TOP

AUTOMATIC AUTOCLAVE

POROUS LOAD AUTOCLAVES

POROUS LOAD AUTOCLAVES

• To achieve complete sterilization a temperature of 121°C at 20 psi is maintained for 20 minutes.

• The articles which can be sterilized by this method include: towels used for draping, suture materials, cotton rolls, rubber gloves,etc.

Small portable bench model type auto claves

• For complete sterilization, 136°C at 32 psi are maintained for 5 minutes. The steam entering the top of the chamber penetrates the material in a top to bottom flow

Wrapping of instruments for autoclaving

Instruments must be clean, but not necessarily dry. Cassettes, drums, trays with opening on all sides may be used. Packaging used for autoclaving must be porous to permit

steam to penetrate through and reach the instruments. The materials used for packaging could be fabric or sealed

biofilm/paper pouches, nylon tubing, sterilization wrap, and paper-wrapped cassettes.

DRY HEAT SRERILIZATION• an alternative method of sterilization of sharp instruments. Action: dehydration and oxidation of microorganisms.

• the instruments do not rust

• the process is time consuming. • carbon steel instruments can loose

their hardness because of dry heat.(Custer and Coyle ,1970)

DRY HEAT STERILIZATION

HOT AIR OVEN

COX RAPID HEAT STERILIZER

HOT AIR OVEN

• It is used to sterilize items which do not get damaged by high temperatures, such as laboratory glassware, glass syringes and instruments.

COX RAPID HEAT STERILIZER

approved by the FDA for a 6-minute sterilization cycle at 375°F for unwrapped instruments.

Cox Sterile Products, Dallas, Texas

circulating air over a heating element

the sterilizing chamber

containing the

instruments to be

sterilized

back to the heater to be

cycled through the

system

eliminates cold spots in

the sterilizing

chamber and maintains

temperature more evenly

shortening the time required

for sterilizatio

n.

WRAPPING OF INSTRUMENTS FOR DRY HEAT STERIIZATION

• The instruments must be clean and dry prior to wrapping. The wrapping material must be heat resistant. Aluminum foil, metal, and glass containers may be used in dry heat oven.

GLASS BEAD STERILIZER

• heat transfer device.• employs submersion of small

instruments such as endodontic files and burs, into the beads and are sterilized in 10 seconds provided they are clean.

• Studies indicated that if orthodontic bands are sterilized by using glass bead method, 15 seconds is required to sterilize bacteria and 45 seconds required for spores. If five bands were placed in the bead sterilizer simultaneously, twice the time was required for sterilization

Am J Orthod Dentofacial Orthop.1986 Sep;90(3):243-9.Glass beadsterilization of orthodontic bands.Smith GE.

CHEMICAL VAPOR STERILIZATION

• dry saturated steam+formaldehyde bacteria spores,viruses

Destruction due to double action by heat and formaldehyde

• lack of corrosion of instruments.• shorter duration of sterilization cycle.• the sterilization is achieved at a low

temperature(73°C),

INSTRUMENT STERILIZATION IN ORTHODONTIC OFFICES, ROBERT.E.MATLACK DDS,MS

ETHYLENE OXIDE GAS STERILIZATION

• highly penetrative• non corrosive agent.

destroys micro organisms by alkylation and causes

denaturation of nucleic acids of microorganisms

• excellent sterilizer of heat sensitive items. • does not require heat above room

temperature.

• toxic• allergenic• requiring a long exposure time of 2 to 6 hours • explosive if mixed with air.

CARBONDIOXIDE

RADIATION USED FOR STERILIZATION

IONIZING RADIATION

X-rays,

gamma rays

high-speed electrons

NON-IONIZING RADIATION

Ultraviolet

Infrared rays

It is commonly used to sterilize disposable materials such as needles syringes ,swabs , culture plates etc.

• effective for heat labile items.

• has great penetrating properties

IONIZING RADIATION

Advances in Applied Microbiology Volume 1 1959, Pages 49–73

NONIONIZING RADIATION

ULTRAVIOLET INFRARED

MONITORING STERILIZATION

PHYSICAL

CHEMICAL

BIOLOGICAL

• PHYSICAL MONITORING :-

Refers to periodical observation of displays or gauges on

the sterilizer during a cycle to ensure the sterilization

process.

CHEMICAL MONITORING Process indicators :- consist of colour changing material

(liquid /paper) which changes color upon exposure to appropriate sterilization cycle.

TST strips (TIME ,STEAM,TEMPERATURE) change color when all parameters have been adequately achieved in the sterilization cycle.

BIOLOGICAL INDICATORS• Indicator used are heat resistant bacterial spores.

• If the spores are killed ,then less resistant microbes are killed more readily and sterility is achieved.

DISINFECTANTS USED IN ORTHODONTICS

• Glutaraldehydes.• Quaternary ammonium

compound• Chlorine compounds.• Iodophors.• Synthetic phenolics.

GLUTERALDEHYDE

• 20 min immersion in a 2% alkaline

gluteraldehyde solution - disinfection.

• 6 -10 hours immersion – sterilization.

-Noncorrosive.-Penetrates blood, pus & organic debris.

-Induces severe tissue irritation upon prolonged contact.-Discolors nickel coated impression trays & carbon steel burs.

QUARTENARY AMMONIUM COMPOUND

-Bactericidal against gram positive bacteria.-Non –irritating.-Economical.-Pleasant odor.

-inactivated by organic matter.-Can sometimes support gram negative bacteria.-Easily inactivated by presence of anionic detergents, soaps &hard water.

CHLORINE COMPOUNDS

• Rapid antimicrobial action.

• Effective in dilute solution.

• Economical

• Prepared solution has only limited shelf life.•Activity diminished by presence of organic matter & altered Ph.• Unpleasant odor• Irritates skin &eyes.• Can degrade plastic & rubber coated

instruments.

IODOPHORS

-Broad spectrum disinfectant, especially effective against heavy viral contamination.-Biocidal activity occurs within 3-30 min.-Effective in dilute solution

-Unstable at high temperature.-Must prepare daily.-Inactivated by hard water.-May discolor some light colored surfaces.

AD

VAN

TAG

ES

DISA

DVA

NTA

GES

SYNTHETIC PHENOLSThey act as a protoplasmic poison which precipitate the protein and destroy the cell wall synergistic effect instead of additive.• Broad antimicrobial spectrum.• Can be used on metal, glass, rubber &plastic.• Less toxic & corrosive.• Economical.

• Not a sterilant• No re-use life.• Irritates skin & eyes.

Omidkhoda et al

Autoclaving, Gluteraldehyde and Deconex spray

Autoclaving and glutaraldehyde solution are the best methods for disinfecting orthodontic markers.

Omidkhoda, et al.: Disinfection methods on orthodontic markers

Mayhew et al

Effects of sterilization on the mechanical properties and the surface topography of nickel titaniumarch wires, AM J ORTHOD DENTOFAC ORTHOP t 988;93:232-6.)

• Neither the heat sterilization nor multiple cycling procedures had a deleterious effect on the elastic moduli,surface topography, or tensile properties of Nitinol or Titanal arch wires.

SURFACE COVER

• Materials impervious to moisture.• On surfaces difficult to clean.• To be changed between patients. (impervious- backed paper, aluminium foil /plastic covers )

Spray – wipe spray technique.

Disinfecting dental equipments.

Most are autoclavable.Depends on manufacturers guidelines.After sterilization ,lubrication is mandatory.Hand piece is placed in autoclavable pouch with TST strips.

HAND PIECES

Decontamination inside and outside

RinseFlush lines

Dry Sterilize

LubricateBag wrap

Steps for proper sterilization of hand pieces.

Suck –back devices / check valves on hand pieces

• 3 –way syringe should be treated in the same manner as hand piece.

• HVE tips –metal tips are autoclavable. Plastic tips must be disposed off after single use.

• Aspirators –disinfectant flushes for the aspirators should be done after each patient.

Sterilization & disinfection of individual articles.

ALGINATE:- iodophores / glutaraldehyde – 15min

Burs• ethylene oxide 4-12 hours• autoclave.

Carbon steel instruments• chemical vapour---20 min at 270 °f• ethylene oxide ----4-12hours• dry heat oven---60-120 min at 320°f

Tungsten carbide instruments • chemical vapour-20 min at

270 °f• dry heat oven-60-120 min at

320°f

Drake et al,

• Plastic items & heat sterilizable cheek retractors – immersed in procide (sterlization solution whish turns milky after autoclaving)

• Hand pieces & photographic mirrors – sterilized in a kavo-klave

• Plier racks & instruments are placed in a wire basket & run through an ultrasonic cleaner containing rust inhibiting non-ionic multipurpose ultrasonic cleaner .

• Ultra-sonic solution should be changed daily & covered during cleaning to reduce aerosols.

• Dried blood must be scrubbed off & repeat ultrasonic cleaning .

• Heavy duty nitrile gloves are required for handling contaminated instruments.

• After cleaning, instruments are dipped in a sodium nitrite rust inhibitor

• Autoclave for 20 min &20 min for cooling.

Sterilization in orthodontics,David Drake(1997)JCO

Hohlt et al

Cleaning and sterilizing orthodontic instruments presents special problems.

• Instruments have large hinge areas that are difficult to clean and sterilize.

• Cutting edges, sharp angles, and pointed ends can be damaged easily.

• Inadvertent damage during cleaning and processing is an important economic problem

• Cassettes designed specifically for the management of orthodontic instruments and bands are available.

• These cassettes are designed to contain the instruments or bands during ultrasonic cleaning, subsequent sterilization, and actual use at chairside.

CAUSES OF STERILIZATION FAILURE

• CYCLE TIME TOO SHORT• TEMPERATURE TOO LOW• FAILURE TO PREHEAT• FAULTY STERILIZER• INTERRUPTING OF CYCLE• OVERLOADING OF CHAMBER• INADEQUATE STAFF TRAINING• IMPROPER PRECLEANING, PACKAGING• FAILURE TO USE BIOLOGICAL INDICATOR TESTING.

Vendrell et al,

There was no significant difference in the mean wear at the tip of the pliers between the 2 groups. It appears that there is no need to maintain both sterilization systems, dry heat and steam autoclave,in the orthodontic office. Steam autoclave sterilization can be used with no deleterious effects on the pliers if they are manufactured with stainless steel inserts.

Effect of steam versus dry-heat sterilization on the wear of orthodontic ligature-cutting pliers Ricardo J. Vendrell,

Effect of steam versus dry-heat sterilization on the wear of orthodontic ligature-cutting pliers

Smith et al,

No clinically significant differences were found between new and used arch wires.

• nickel-titanium • βtitanium • stainless steel arch wire

The sterilization/disinfection procedures included:• disinfection• steam autoclave• dry heat• cold solution sterilization

The effect of clinical use and orthodontic arch wires sterilization on selected orthodontic arch wires

The effect of clinical use and orthodontic arch wires sterilization on selected orthodontic arch Glen A. Smith,

With solution corrosion, strong solutions such as blood or saliva form the electrolyte and cause corrosion as either an acid or a strong base.With debris (interface) corrosion, debris such as cement or dried blood sets up a potential difference, resulting in electron flow and rust at the edges

Corrosion of instruments

Heat itself will not cause corrosion, but it accelerates the process by increasing the rate of molecular reaction

The corrosion resistance of orthodontic grade steel is directly proportional to its chromium content and inversely proportional to its carbon content No steel is truly "stainless", but stainless steel protects itself by forming a protective chromium oxide layer from oxidation products of the alloy.

Lip burn from band seater

• The band seater was placed in Ultrasonic cleaner for 5 minutes.

• The cleaning solution - contains sodium hydroxide. Following thorough rinsing under running water, the instrument was placed in a Glutaraldehyde solution overnight.

• The next morning it was thoroughly rinsed, dried, and returned to storage.

Robert N. MooreAmerican Journal of ORTHODONTICS and DENTOFACIAL ORTHOPEDICS Volume 93 Number 3 March 1988

• During its next use to seat a mandibular right molar band, the patient experienced a painful burning sensation of the lower lip. Within a few minutes, an intense edema occurred creating a soft, fluctuant mass near the right commissure

• The instrument had a tarnished area at the junction of the shaft and the handle. On closer inspection, it was found that a clear fluid leaking from this area and crystallization occurring at the periphery.

• This led to suspect that the chemical burn experienced by the patient was caused by a combination of sodium hydroxide and glutaraldehyde leaking from the instrument

DISPOSAL OF WASTE•Its should be disposed in tamper proof containers/ boxes.•Its should be labeled as BIOHAZARD.•Should be in tune with the existing laws of the area.•Sharp material should be stored in hard walled leak proof containers ,red in color.

•Yellow --- waste for incineration .•Yellow with --- waste for land fill

black stripes •Light blue --- for autoclaving before disposal•Red ---human anatomical wastes.•Black ---normal household wastes.

REFERENCES• Effects of sterilization on the mechanical properties and the surface topography of nickel

titaniumarch wires, Am J Orthod Dentofac Orthop t 988;93:232-6.)• Effect of steam versus dry-heat sterilization on the wear of orthodontic ligature-cutting

pliers, Ricardo J. Vendrell, (Am J Orthod Dentofacial Orthop 2002;121:467-71)• Instrument sterilization in orthodontic offices, Robert.E.Matlack DDS,MS, Am J Orthod

Dentofacial Orthop 1979;Vol3:205-209)• Comparison of three different sterilization and disinfection methods on orthodontic

markers,Maryam Omidkhoda, J Orthod Sci. 2016 Jan-Mar; 5(1): 14–17• The effect of clinical use and orthodontic arch wires ste ilization on selected Glen A. Smith,

(Am J Orthod Dentofac Orthop 1992;102:153-9.) • Journal of clinical orthodontics-FAILURES• Lip burn from band seater, Robert N. Moore, American Journal of Orthodontics And

Dentofacial Orthopedics Volume 93 Number 3 March 1988

• Kohn WG, Collins AS , Cleveland JL, Harte JA, Eklund KJ, Malvitz DM, Centers for Disease Control and Prevention (CDC). Guidelines for infection control in dental health-care settings—2003

• Glass bead sterilization of orthodontic bands Gerald E. Smith, (Am J Orthod Dentofac Orthop 90: 243- 249, 1986.)

• Disinfection, sterilization, and preservation, CA Lawrence, , Lea & Febiger, Philadelphia, (669-685) ,1968

• The use of a rapid heat transfer sterilizer when bagging instruments before sterilization, December 1994,Volume 106, Issue 6, Pages 627–634

• The effect of sterilization in tensile strength of orthodontic wires, Staggers Margeson,(AO Vol 63, No2 141-144,1993)

• Advances in Applied Microbiology Volume 1 1959, Pages 49–73• Optimizing orthodontic sterilization techniques,Drake DL Journal of Clinical Orthodontics :

JCO[1997, 31(8):491-498]