BASICS OF STERILIZATION FOR STUDENTS. INSTRUMENT STERILIZATION PPE autoclave methods of sterilization handwashing gloving

1. Principles of Sterilization and Disinfection
DR LEKSHMI S NAIR
1ST MDS

2. CONTENT
INTRODUCTION
TERMINOLOGIES
HISTORY
METHOD OF STERILIZATION
STERILIZING AGENTS
RECENT ADVANCES IN STERLIZATION
STERLIZATION IN DENTISTRY
INFECTION CONTROL
INFECTION CONTROL AS PER COVID PROTOCOL
WASTE MANAGEMENT
CONCLUSION
REFRENCES

3. INTRODUCTION

4. STERILIZATION- Validated process used to render a product free of all forms of
viable microorganism. In a sterilization process, the presence of microorganism
on any individual item can be expressed in terms of probability. Although this
probability can be reduced to a very low number it can never be reduced to
zero.(CDC glossary 2008)
TERMINOLOGIES

5. DISINFECTION-Thermal or chemical destruction of pathogenic
and other types of microorganisms. Disinfection is less lethal
than sterilization because it destroys most recognized
pathogenic microorganisms but not necessarily all microbial
forms (e.g., bacterial spores).(CDC glossary 2008)
High-level disinfectant
Intermediate-level disinfectant
Low-level disinfectant

6.  Decontamination-According to OSHA, “the use of physical or chemical means to remove,
inactivate, or destroy blood borne pathogens on a surface or item to the point where they
are no longer capable of transmitting infectious particles and the surface or item is
rendered safe for handling, use, or disposal”. In health-care facilities, the term generally
refers to all pathogenic organisms.
 Cleaning-removal, usually with detergent and water or enzyme cleaner and water, of
adherent visible soil, blood, protein substances, microorganisms and other debris from the
surfaces, crevices, serrations, joints, and lumens of instruments, devices, and equipment by
a manual or mechanical process that prepares the items for safe handling and/or further
decontamination.

7.  Antiseptic-Substance that prevents or arrests the growth or action of
microorganisms by inhibiting their activity or by destroying them. The
term is used especially for preparations applied topically to living
tissue.(e.g.- chlorhexidine, povidone iodine, hydrogen peroxide)
 Germicide-Agent that destroys microorganisms, especially pathogenic
organisms.

8. HISTORY
• 3000 BC-Tar ,pitch, resins were used as antiseptics by Egyptians in embalming
bodies
• 300 BC – Hippocrates kept wounds clean by using boiled water and wine for
disinfection
• 1800s heat sterilization was introduced
• 1885- Gaston Poupinel introduced 1st dry heat sterilization device which was being
used in many hospital

9. • 1860-Louis Pasteur French chemist and
microbiologist gave germ theory and later developed
the method of pasteurization
• 1867- Jospeh Lister “Father of Antiseptic Surgery”.
Used carbolic acid solution to disinfect operating
area

10. • 1879- Robert Koch demonstrate the usefulness of steam for
sterilizing surgical instruments and dressings
• 1879- Charles Chamberland a French microbiologist developed
the Chamberland filter which led to the invention of autoclave
device

11. METHODS OF STERLIZATION AND DISINFECTION
PHYSICAL CHEMICAL
SUNLIGHT HEAT RADIATION FILTRATION
DRY HEAT MOIST HEAT NON IONIZATION
IONIZATION
EARHTENWARE
ASBESTOS
SINTERED GLASS
MEMBRANE
LIQUID
GASEEOUS
INCINERTION
FLAMING
RED HEAT
HOT AIR OVEN
BELOW100
AT 100
ABOVE 100
ALCOHOL
ALDEHYDE
HALOGEN
PHENOLS
ETHYLENE OXIDE
FORMALDEHYDE
PLASMA

12. PHYSICAL AGENTS
1.HEAT- The most reliable method of sterilization. Factors influencing heat sterilization
• Nature of heat
• Time and temperature
• Number of micro organism
• Characteristics of organism
• Type of material to be sterilized
Dry heat – Mechanism of action can be due to
• Protein denaturation
• Oxidative damage
• Toxic effect of elevated electrolyte levels
1. Flaming
2. Red heat
3. Incineration
4. Hot air oven

13. • PRINCIPLE- Works on the principle of conduction. The heat is
absorbed by the outer surface of the item and then moves to
the centre, layer by layer. The item will eventually reach the
temperature required for sterilization. Most damage is done
by oxidizing molecules. Essential cell constituents are
destroyed and organisms die.
• Most common temperatures used- 170 for 30mins
160 for 60mins
150 fro 110mins
PARTS OF HOT AIR OVEN
HOT AIR OVEN

14. • Precautions to be taken-Not be overloaded
Not be crowded
Glassware should be wrapped and dry
Cooled slowly before opening
• Materials sterilised-glassware, swabs, liquid paraffin, dusting powder, fat and grease, scissors,
scalpels, glass syringes
• Quality Controls- Chemical- Browne’s tube
Physical-Thermocouple
Biological-paper strips containing 106 spores of Clostridium tetani

15. 1. Temperature below 1000C
• Pasteurisation- Usually used for food like milk.
Non sporing bacteria like mycobacterium, salmonella destroyed
• Vaccine Bath- 600C for 1 hour
Water bath used to sterilize vaccines
2. At 1000C
• Boiling- Means of disinfection.
Not used for surgical instruments
• Tyndallisation/intermittent sterilization – Steam at atmospheric pressure
used to sterilize culture media
3. Above 1000C
• Autoclave
Moist Heat

16. Autoclave
Steam under pressure used.
Principle-
• Water boils when vapour pressure equals atmospheric pressure.
• When pressure inside closed vessel increases the temperature at
which water boils increases.
• The steam produced condenses to water on cool surfaces giving out
latent heat.
• Steam has high penetrative power.
• Process continues till temperature of surfaces rises to that of steam.

17. Common operating parameters-
TEMPERATURE TIME PRESSURE
121 15mins 15psi
126 10mins 20psi
130 3min 25psi
Several steps involved in sterilization process
• Instrument reception
• Pre cleaning disinfection
• Pre sterilization cleaning
• Packing
• Autoclaving
• Drying
• Storage

18. Mechanism of action

19. Types of autoclaves useful for dental surgeries
1. Displacement autoclave-Utilize superheated steam to displace air downwards and out of
the chamber
Used for sterilization of unwrapped instruments.
Typically small bench units
2. Vacuum autoclaves - Pump air from the chamber before entry of super heated steam
Preferred for porous load.
Larger and more costly units

20. Advantage
• Absolute sterility
• Short cycle time
• Loose or bagged instruments are
acceptable
• Good penetration of steam
• Ability to process a variety of
material
• Readily monitored
Disadvantage
• Corrosion of materials
• Cutting edges may dull
• Damage heat sensitive
materials
• Wrapped items remain wet
without drying cycle
• Wrapped items need longer
cycle

21. Errors in effective use of autoclave
• Human error- Inadequate cleaning, improper packaging, over loading, incorrect
choice of cycle, items not dried after, improper storage, manual alteration of cycle
• Equipment factors-Clogged filters, leaking door gaskets, faulty timer, out of
calibration of sensors, low water level, controller malfunction
Quality control
Physical- Monitoring gauges and Thermocouples
Chemical- Browne’s tube
Biological- Strips or tapes of Bacillius stearothermophillus

22. Filtration
Help remove bacteria from heat labile liquids
ASBESTOS FILTER
SINTERED GLASS FILTER
CANDLE FILTER
MEMBRANE FILTER

23. Radiation
2 types radiation
• Ionising
• Non ionising
• Ionising radiation- Gamma, X ray
o Short wavelength
o Cold sterilization ,as no temperature increase
o High penetrating power damages DNA and other cell
components
o Sterilization of implants ,sutures ,swabs, plastics

24. • Nonionizing- UV radiation ,Infrared
• UV has bactericidal action at 240-280nm
o Long wavelength
o Low penetrating power
o Germicidal radiation
o Breaks down chemical bond and disrupts
DNA,RNA and proteins
o Used for surface sterilization, syringes,
catheters, operating rooms

25. Ultrasonic and sonic cleaning
• Vibrations used fro cleaning instruments
• More effective than manual cleaning
• Used before autoclaving
• Removes plaque, calculus and other dental materials from the
surfaces
of instruments
• Minimises handling of contaminated instrument
• Instruments are submerged in ultrasonic solution

26. Chemical agents
Ideal requisites
• Wide spectrum of action
• Active in the presence of organic material
• Speedy action
• Effective in acid and alkaline environment
• High penetrating power
• Stable

27. • Compatible
• Non irritating and non allergic
• Non toxic
• Inexpensive
Methods of action
• Protein coagulation
• Disruption of cell membrane
• Remove free sulfhydryl groups
• Substrate competition

28. ALCOHOL
• Commonly used ethyl alcohol and isopropyl alcohol
• Acts by denaturing proteins
Used as
• Skin antiseptic
• Surface disinfectant
• Hand sanitizer
Disadvantages
• Inflammable
• Irritant
• Promotes rusting

29. ALDEHYDE
FORMALDEHYDE
• Aqueous and gaseous form
• Bactericidal and sporecidal
Liquid-
• 37% formaldehyde solution, water based- FORMALIN
Mode of action-
• Inactivates microorganism by alkylating the amino and
sulfhydryl groups of proteins and ring nitrogen atoms of
purine bases , alter RNA ,DNA ,protein synthesis

30. Gaseous-Fumigation
• 150gms of KMNO4 in 280 ml of formalin for 1000cu. feet
room volume
• Operation theatres labs and wards
• Doors should be left sealed for 48hrs.
Disadvantage
• Can be fatal to health
• Skin irritation and respiratory disorders on long term use.
GLUTARALDEHYDE
• 2.4% Cidex
• Less toxic
• High level disinfectant and chemical sterilant

31. HALOGEN
Chlorine Compounds
• Hypochlorite, sodium hypochlorite(0.5%-1%)
• Most commonly used for canal irrigation and antiseptic
• Antimicrobial activity by reacting with fatty acid and amino acids
• Unaffected by water hardness and do not leave toxic residue
• Should be prepare daily because of its instability

32. Iodine
• Povidone iodine
• Antimicrobial action
• Used as mouth rinse (2%,5%),surgical scrub(7.5%,10%),
antiseptic for wound dressing
• Iodine penetrates cell membranes and interact with
proteins, nucleotides and fatty acids

33. PHENOL
• Used as germicide
• Penetrating and disrupting cell wall and precipitating cell
protein
• Used as surface disinfectants and for non critical item
• LISTERINE Mouth was contains phenolic compounds

34. HYDROGEN PEROXIDE
• Germicidal effect
• Active against wide range of organisms
• Destructive hydroxyl free radicals released that attacks DNA and other cell components
• 3% used as canal irrigant, flushing debris,antiseptic
ETHYLENE OXIDE GAS
• Reacts with DNA and RNA and has alkylating effect
• Highly inflammable and explosive long cycle time, cost, potential occupational hazard
• Used to sterilize critical and semi critical items that are heat sensitive and cannot he sterilized by heat

35. RECENT ADVANCES
Hydrogen Peroxide Gas Plasma
• Generated in a closed chamber under deep vacuum using radiofrequency or microwave to
excite gas molecules and produce large molecules which are in the form for free radicles
• Free radicals interact with essential cell components and disrupt them
• Used for materials that are not heat stable, plastics, electrical devices corrosion susceptible
metal alloys
OZONE
• Low temperature sterilization method
• Stainless steel instruments compatible
• Cycle time 4.5 hours

36. Factors Affecting the Efficacy of Disinfection and Sterilization
• Number and location of microorganisms
• Innate resistance
• Concentration and potency of disinfectant
• Physical and chemical factors
• Organic and inorganic matters
• Duration of exposure
• Biofilms

37. Sterilization And Disinfection In Dental Clinics
• To determine the type of method used for disinfection or sterilization Spaulding classified the instruments into
CRITICAL
• Those that entre tissue and vascular
system
• Infection transmission maximum
• Heat sterilization followed
• Surgical instruments, scalpels, scaler,
implants
SEMI-CRITICAL
• Come in contact with mucous membrane and
non intact skin
• If heat stable sterilized by heat and if heat
sensitive high level disinfectant used
• Dental mouth mirror, amalgam condenser,
impression trays, dental hand pieces
NON CRITICAL
• Contact intact skin
• Chances of transmitting infection least
• Disposable barrier protection can be used
• Radiograph head, blood pressure cuff, pulse
oximeter, other environmental surfaces

38. STERILIZATION OF DENTAL OPRATORY
1. DENTAL CHAIR
• Control unit should be covered by disposable plastic covers and disinfected using
formaldehyde or alcohol based disinfectant
• Tubes connecting water pipes , air and water syringes and scaler units also serve as
reservoir for microorganisms
• Water units should be maintained and monitored
• Discharge water and air syringe for a minimum for 20-30 seconds after each patients
• Use anti retraction valve or one way flow check valve to prevent backflow
• Use bacterial filters and chemical disinfection

39. 2. DENTAL RADIOGRAPH
• Gloves should be worn
• Heat tolerant accessories available should be heat
sterilized
• Films should be dried and disposable towels should be
used
• Digital sensors can be disinfected and plastic barriers can
be used
• Plastic attachments disinfected using chlorhexidine
solution
• X ray tube and head buttons cleaned with detergent

40. 3.ULTRASONIC SCALERS
• Hand piece is disinfected
• The inserts are removed and cleaned of all debris with water and then
disinfected and places in cassettes or pouched and autoclaves
5.ROTARY INSTRUMENT
• Diamond carbide bur-0.2% Gluteraldehyde and sodium
phenate for 10mins
• Autoclave or dry heat
• Steel burs- Glass bead sterilizer 230 degree for 20-30 mins

41. 4.DENTAL HANDPIECE CONTAMINATION CONTROL
• Run under water
• Scrub
• Clean fibre optic surface with alcohol
• Lubricate and run hand piece
• Place in sterilization pouch
• Autoclave

42. INFECTION CONTROL
• Transmission of infection within the dental clinic can occur from
• Infection control begins at taking a proper case history and making sure all protective
measures are in place
• Protective coverings, hand protection, immunisation of operator, protective shields,
instrument sterilization helps control infections
PATIENT
OPERATOR
OTHER
PERSONAL

43. HAND HYGENE PROCEDURE

44. GLOVES AND GLOVING TECHNIQUE

45. GLOVE REMOVAL TECHNIQUE

46. GOWNING TECHNIQUE

47. PERSONAL PROTECTIVE EQUIPMENT

48. Principles And Procedure For Handling And Cleaning Instruments After Treatment
• Receiving
• Cleaning
• Decontamination
• Preparation
• Packaging
• Sterilization
• Storage

49. INFECTION CONTROL AS PER COVID PROTOCOL
Zones and Dental clinics
• Containment zone- Closed
• Red zone-Emergency procedure
• Orange and green- Emergency and urgent treatment consults
Phase1- Preparatory Phase
Doctors and other health care workers
• Testing and prophylaxis should be taken before resuming work
• Proper training should be given, use of N95 masks, proper donning and doffing of PPE,
hand hygiene should be practiced

50. Dental clinics
• Ventilation and air circulation should be checked
• Fan should not be used while performing procedure
• Window ac filter should be cleaned regularly
• Strong exhaust should be used
• Visual alters and instructions should be displayed
• Sanitizer and masks should be provide to the patient

51. • Distant waiting chairs should be placed- 1m apart
• Consultation should be based on appointments spaced out properly
• Cashless or contactless payment
• Changing area for PPE donning and doffing
• Dedicated areas for sterilization

52. Equipment and instruments
• Fumigation system in place
• High volume suction
• Hand piece with anti retraction valve
• Indoor air cleaning system
• Environmental surfaces disinfected using 1%sodium hypochlorite for 10 mins
• Delicate electronics alcohol based disinfectant used

53. Phase2-Implentation phase
• Telconsult
• Protocols to handle patients in clinic area
• For consultation- 3 layered mask, face shield and gloves
• For procedure- N95 and PPE used
• Rubber dams should be used and practice non aerosol generating procedures
• Patients draped
• Patient made to rinse mouth with 10ml 0.5% povidone iodine
• Patient discharge- drape removed, patient made to wash hands
• Procedure and prescription recorded after doffing PPE
• Disinfection done
• Hand piece washed under water

54. • Forced ventilation using high efficiency particulate air filter
• 3 way syringe run for 30-40sec and flushed with disinfectant solution
• Remove water container and disinfect with 1%sodium hypochlorite, refill
• Disinfect chair and auxiliary parts within 3 feet with 1% sodium hypochlorite
• Fogging-hydrogen peroxide 11% solution stabilized with 0.01% silver nitrate 20% working
solution prepared. 1000 ml per 100 cu feet. Time 45 mins, after procedure close room for
half an hour.
Phase 3-
• Patient follow up
• Patient contacted with 24hrs and 1 week to know if he has developed and symptoms.

55. WASTE MANAGEMENT
• The collection ,transport , recovery and disposal of waste including the supervision of such operations
and after care of disposal sites
• Biomedical waste- Any waste generated during diagnosis , treatment or immunisation of human
beings or animals or research activities.
CLASSIFICATION
• Infectious waste
• Sharps
• Pharmaceutical waste
• Chemical waste
• Heavy metal waste
• Pressurized containers
• Radioactive waste

57. CONCLUSION
With the increase in number of transmissible diseases and
increasing hospital acquired diseases ,the risk of infection
increases for both the patient and health care workers.
Hence it is important to follow high standards of infection
control for the safety of the patients and the dental health
care workers

58. REFERENCES
1. Text book of microbiology, Anantanarayan 9thed.
2. CDC Recommendations from the guidelines for infection control in dental health care
settings-2003
3. CDC Guidelines of infection control in dental clinics
4. COVID19 Pandemic: What changes for dentists and oral medicine experts? A narrative
review and novel approaches to infection containment, Maria Elenora Bizzoca et al,
International Journal of Environmental Research and Public Health 2020,17,3793
5. WHO recommendation for hand hygiene procedure

59. 6. Government of India Guidelines for dental professionals in covid19
pandemic situation-2019
7. Sterilization protocols in dentistry-A review, Lakshya Rani and Dr
Pradeep, Journal of Pharmaceutical Sciences and Research.vol.8(6),
2016,558-564
8. CDC guidelines for disinfection and sterilization in healthcare facilities,
William A Rutala et al,2008
9. The use of autoclaves in dental surgery, N W Savage and L J Walsh,
Australian Dental Journal 1995;40(3):197-200
10. Google images