INFECTION CONTROL IN PROSTHODONTICS

1. INFECTION CONTROL IN
PROSTHODONTICS
PRESENTED BY:
DR.ROHIT B.PATIL
MDS I

2. CONTENTS
• Introduction
• Definitions
• Transmission of infection
• Objectives of cross-infection control
• Infections of concern in dentistry
• Methods of sterilization and disinfection
• Personal protection
• Instrument sterilization
• Infection control in prosthodontics & dental laboratory
• Disposal of waste & sharps
• Summary and conclusion
• References

3. INTRODUCTION
• Infection control in dentistry continues to be the
subject of intensive research and debate.
Implementing safe and realistic infection control
procedures requires the full compliance of the whole
dental team.
• Health professionals themselves are at greatest risk
from cross infection as the oral cavity harbors many
potentially pathogenic microorganisms.

4. • Thus, it is the responsibility of the individual
practitioner to ensure that all members of the dental
team understand and practice these procedures
routinely.
• Every practice must have an infection control policy
which is tailored to the routines of the individual
practice and regularly updated.

5. DEFINITIONS

6.  STERILIZATION (GPT 8)- The process of completely
eliminating microbial viability.
The process by which a surface or medium is freed of all
micro-organisms either in vegetative or spore state.
 DISINFECTION- The destruction or removal of all pathogenic
organisms, or organisms capable of giving rise to infection.
 ANTISEPSIS- The prevention of infection, usually by inhibiting
the growth of bacteria in wounds or tissues.

7.  ANTISEPTICS- Chemical disinfectants which can be safely
applied to skin or mucous membrane and are used to prevent
infection by inhibiting the growth of bacteria.
 INFECTION CONTROL – (Exposure control plan)It is required
office program that is designed to protect personnel against
risk of exposure to infection.
 DECONTAMINATION- The process of rendering an article or
area free of danger from contaminants, including microbial,
chemical, radioactive and other hazards.

8. 1.From lesions on
Operator’s
ungloved hands.
2. Contaminated
operator's
ungloved hands.
3.Contaminated
instruments or other
equipments.
TRANSMISSION OF INFECTION
Source of
Infection
Risk to
Patient
Risk to
Dental staff
1. Injuries by
contaminated
instruments.
2.Existing lesions on
the operator’s hands.
3.Dental aerosol
Splashes of
contaminated material.
1.Patients suffering
from acute infection.
2.Patients in
prodormal stage of
infection.
3.Carriers( Known
and unknown).

9. OBJECTIVES OF CROSS
INFECTION CONTROL

10. 1) To protect patient and members of dental staff team from
contracting infections during dental procedures.
2) To reduce the numbers of pathogenic micro-organisms in
the dental environment to the lowest possible level.
3) To implement a high standard of cross infection control
when treating every patient to prevent transmission of
infection (UNIVERSAL PRECAUTIONS).
4) To simplify cross infection control allowing dental team to
complete dental procedures with minimal inconvenience.

11. INFECTIONS OF CONCERN
IN DENTISTRY

12. MICRO-ORGANISMS TRANSMITTED BY
INOCULATION
• Hepatitis B HBV
• Non-A, Non-B Hepatitis HCV
• Delta Hepatitis HDV
• Oral Herpes, Herpetic whitlow HSV-1
• Genital Herpes HSV-2
• AIDS, ARC HIV
• Syphilis Treponema pallidum
• Wound infections, Abscesses P. aeruginosa,
• Wound infections, Abscesses S. aureus, S. albus
• Tetanus C. tetani

13. MICRO-ORGANISMS TRANSMITTED BY
INHALATION
• Chicken pox V.zoster
• Measles/ Mumps Rubeola/ mumps virus
• Influenza, Common cold Influenza/rhinovirus
• Tuberculosis M. tuberculosis
• Oral abscess, endocarditis Strep. pyogens
• Rheumatic fever Strep. Pyogens
• Candidosis (Opportunistic) C. albicans

14. METHODS OF STERILIZATION AND
DISINFECTION
Physical methods Chemical methods

15. PHYSICAL METHODS
I. Sunlight
II. Drying
III. Dry heat
IV. Moist heat
V. Filtration
VI. Radiation
VII. Ultrasonic and sonic vibrations

16. 1.HEAT
• Most reliable method of sterilization and method of choice
unless contraindicated.
Factors influencing sterilization by heat :
a. Nature of heat – dry or moist.
b. Temperature and time.
c. Number of micro-organisms present.
d. Characteristics of organism eg. species, strain, sporing capacity.
e. Type of material from which organism has to be eradicated.

17. A.DRY HEAT
MECHANISM OF ACTION: By protein denaturation, oxidative
damage & toxic effect of elevated electrolyte levels.
1) Flaming
2) Incineration
3) Hot air oven

18. B.MOIST HEAT
Mechanism of action - Denaturation and coagulation of proteins.
a. Temperature below 100oC
• Pasteurization –Hold Method and Flash Method.
• Vaccine bath – for vaccines
b. Temperature at 100oC
• Tyndallization
• Boiling
• Steam Baths
c. Temperature above 100oC - Autoclave

19. Autoclave :
Pressure (psi) Temperature Time (mins)
15 121 15
20 126 10
20 134 3

20. Wrapping instruments for autoclaving
• Instruments must be clean, but not necessarily
dry.
• Packaging used for autoclaving must be porous,
to permit steam to penetrate through and
reach the instruments.
• Cassettes, drums, trays with opening on all
sides may be used.
• The materials used for packaging could be
fabric or sealed biofilm/paper pouches,
sterilization wrap, and paper wrapped
cassettes. The bag or wrap is heat sealed or
sealed with tape.

21. • Removes bacteria from heat labile liquids like sera & solution of
sugar or antibiotics used for preparation of culture media.
• Types of filters:
 Candle filters: Used for the purification of water for industrial &
drinking purposes. They are of 2 types, unglazed & diatomaceous
earth filters.
 Asbestos filters: Disposable. ( Disadvantage: Carcinogenic potential)
 Sintered glass filters: Brittle & expensive.
2.FILTERATION

22. 3.RADIATION
1) Non-ionising radiation: Infrared radiation is used for rapid mass
sterilization of prepacked items eg. Syringes, catheters.
UV radiation is used for disinfecting enclosed areas like operation
theaters, laboratories.
2) Ionising radiation: Very high penetrative power. Since there is
no appreciable increase in the temperature, it is also known as
COLD STERILIZATION. Used for sterilizing plastics, swabs, metal
foils etc.

23. 4.ULTRASONIC CLEANING
• Ultrasonic cleaning will remove dried serum,
whole blood, plaque, cement from
instruments, metal surfaces and dentures. It
has been found to be more effective than
manual cleaning.
• Ultrasonic cleaning minimizes the handling of
contaminated instruments by the nurse and
reduces the chance of injuries from sharp,
contaminated instruments.

24. CHEMICAL METHODS
I. Alcohols
II. Aldehydes
III. Dyes
IV. Halogens
V. Phenols
VI. Surface-active agents
VII. Metallic salts
VIII. Gases

25. 1.ALCOHOLS
• Ethyl & isopropyl alcohol: Skin
disinfectant. They denature bacterial
proteins, but with no action on
spores. Effective at concentrations of
60-70% in water.
• Methyl alcohol: Effective against
fungal spores. Used to treat cabinets
and incubators.

26. 2.ALDEHYDES
1.Formaldehyde:
• Used at concentration of 10%formalin containing 0.5% tetraborate to
sterilize clean metal instruments.
• Have pungent odor & irritating effect on skin & mucous membrane.
Not recommended for routine use in dentistry.
2. Gluteraldehyde:
• Specially effective against tubercle bacilli, fungi & viruses. It is less
toxic & irritant than formaldehyde. Can be safely used to treat
corrugated rubber anaesthetic tubes, face masks, metal instruments.

27. 3.HALOGENS
1) IODINE: Widely used as skin disinfectant. It is
bactericidal with moderate action against
spores.
IODOPHORS- surface active agents, more
active.
2) CHLORINE:Used commonly as Hypochlorites.
They are bactericidal.
Sodium hypochlorite is available as a house-
hold bleach of 1:10 dilution (1 part of 5% Na
hypochlorite to 9 parts of water).

28. 4.PHENOLS
•They cause lysis of the cell by damaging the cellmembrane and
releasing it’s contents.In low concentrations, it precipitates
proteins.
•Eg.: Lysol, cresAol.

29. 5.SURFACE ACTIVE AGENTS
• They reduce interfacial or surface tension.
• Widely used as wetting agents, detergents, emulsifiers.
• 4 types: anionic, cationic, nonionic, amphoteric
• Cationic compounds are most important and are in form of
quaternary ammonium compounds. Eg. Cetavlon, cetrimide.
(Inactivated by acids).
• Anionic compounds have moderate action eg. Common soaps.

30. 6.DYES
•2 groups, aniline & acridine dyes are used extensively as skin &
wound antiseptics.
•Both are bacteriostatic in high dilution but with low bactericidal
activity.
•Aniline dyes: Brilliant green, Crystal violet.
•Acridine dyes: Proflavine, acriflavine.

31. 7.GASES
• Ethylene oxide: Highly inflammable.Used to sterilize dental
equipments, sutures, clothing.
• Formaldehyde: Widely used to fumigate
rooms and operation theaters.
• Betapropiolactone(BPL): More effective for fumigation than
formaldehyde. (0.2% is used).

32. IDEAL ANTISEPTIC OR DISINFECTANT
• Wide spectrum of activity.
• Active in presence of organic matter.
• Effective in acid & alkaline medium.
• Speedy action.
• High penetrating property.
• Compatible with other antiseptics & disinfectants.
• No local irritation or sensitization.
• Non toxic if absorbed into circulation.
• Cheap & easily available.
• Safe & easy to use.

33. FACTORS AFFECTING EFFICACY OF
DISINFECTION
• Concentration of disinfectant
• Formulation of disinfectant
• Target organism(s)
• Contact time
• Temperature
• Water hardness
• Soil load
• Biofilm presence
• Relative humidity
• Compatibility
• Surface microtopography
• Application method
• Application time
• Storage
• Product age
• Precleaning
Disinfection of surfaces and equipment. Susan Springthorpe. J Can dent Assoc 2000; 66:558-60

34. PERSONAL PROTECTION
( BARRIERS )

35. PERSONAL PROTECTION ( BARRIERS )
• A major component of Standard Precautions.
• Protects the skin and mucous membranes from exposure to
infectious materials in spray or spatter .
• Should be removed when leaving treatment areas.

36. 1.Gloves
• Gloves must be worn when skin contact with body fluids or mucous
membrane is anticipated or when touching items or surface that may be
contaminated with these fluids.
• After contact with each patient, gloves must be removed; hands must be
washed and then regloved before treating another patient.
• Repeated use of a single pair of gloves to disinfectant or other chemicals
often cause defects in gloves, thereby diminishing their values as effective
barrier.
• Latex or vinyl gloves should be used for patient examination and
procedure. Heavy rubber gloves should preferably be used for cleaning
instruments and environmental surfaces.

37. Practical points essential for glove use:
• Wash hands before wearing gloves.
• Choose a glove that fits tightly .
• Replace gloves immediately if torn.
• Ensure chair side assistants wear gloves .
• Wash hands immediately after glove removal.
• Treat gloves as surgical waste and dispose
of them accordingly.

38. 2.Protective clothing
• Gowns, apron, lab coats, clinical jackets or
similar outer garments either reusable or
disposable must be worn when clothing or
skin is likely to be exposed to body fluid.
• Protective clothing should be changed
when visibly spoiled or penetrated by
fluids.
• ADA recommends long sleeved uniforms.

39. 3.Masks
• Effective face masks are to have a minimum filtration of 95%
of 3.5 um particles and ability to block aerosols as well as larger
particles of blood, saliva and oral debris.
• Mask should be properly disposed of after each use and not
left hanging around the neck.
• Make sure before starting work that it is
well adapt to the face.
• Do not reuse masks or pull them down
on the neck.

40. 4.Protective eyewear
• Protective eyewear in combination with a
mask must be worn to protect the eye when
spatter and splash of body fluids is
anticipated.
• Eyewear should be washed with soap first,
and then rinsed with water and an
appropriate surface disinfectant can be
used.

41. 5.Hand wash
• Hands must always be washed at the start of each day before
gloving, after removal of gloves and after touching intimate
objects likely to be contaminated by body fluids from patient.
• For many routine dental procedures, such as examination and
non-surgical procedures hand washing with plain soap
appears to be adequate.
• For surgical procedures antimicrobial surgical hand scrub
should be used.

42. 6.Head covers
• Head covers provide an effective barrier.
• They are recommended during invasive dental
procedures, which are likely to involve extensive
blood splatter.

43. 7.Draping the patient
• The purpose of draping a patient is to isolate
the field of surgery from other parts of body
that have not been prepared for surgery, and
also from non-sterile equipments.

44. DISINFECTION PROCEDURES IN
DENTAL CLINIC

45. 1.PROTECTIVE MEASURES AGAINST BACTERIAL AEROSOLS :
• Bacterial aerosols can be reduced by using air filter and ultraviolet
(UV) light.
• High volume evacuation may reduce bacterial aerosols and splatter
during dental procedures.
• Use of an antiseptic mouthwash by the patient prior to ultrasonic
scaling has also been shown to be effective.
• The use of a rubber dam may also assist in reducing the bacterial
contamination generated during the operative treatment.
• Additional measures may include flushing water lines daily before use.
• H2O2 , ozone ,CHX &12% ethanol can uses as waterline disinfectants.

46. 2.SURFACE DISINFECTION
• The operating surfaces
get contaminated with
saliva, blood or exudates,
so surface disinfection
should be done that is
achieved in 2 steps:
1. Pre-cleaning stage:
Surface is cleaned
thoroughly before
disinfection.
2. Disinfection stage.
Dilution Contact
time
Sodium
hypo.
(5.25%)
1:10 10
minutes
Iodophors 1:213 10
minutes
Synthetic
phenols
1:32 10
minutes

47. 3.USE OF DISPOSABLE ITEMS
• Disposable items should be chosen if an instrument or item cannot
be sterilized or disinfected satisfactorily.
• These are items for single use example:
Needles, saliva ejectors, surgical masks, operating gloves.
• Non- sterile disposable items eg. Rubber dams, saliva ejectors should
be stored in dust free containers and dispensed with clean transfer
forceps.
• Sterile or disinfected items should be stored dry in suitable
containers not submerged in alcohol or other disinfectants.

48. STERILIZATION OF
INSTRUMENTS

49. Layout of sterilization area:

50. STAGES IN INSTRUMENT STERILIZATION
1. Pre-sterilization disinfection using Holding solution.
2. Pre-sterilization cleaning.
3. Sterilization.
4. Aseptic storage.

51. CLASSIFICATION OF INSTRUMENTS
Critical
instruments
Semi-critical
Instruments
Non-critical
Instruments
Based on potential risk transmission of infection CDC (centre of
disease control) has classified instruments as :

52. 1.CRITICAL INSTRUMENTS
• If an instrument will penetrate tissue or touch
bone.
• They should be thoroughly cleaned and heat
sterilized if they are to be reused.
• Example: Scalpel, scissors, forceps, burs and
files.

53. 2.SEMI-CRITICAL INSTRUMENTS
• If an instrument will touch the mucous
membrane but not penetrate the tissue nor
touch the bone.
• It should be sterilized if possible, or high
level disinfection should be done if it may
get damaged during sterilization.
• Example: mouth mirror, probe, tweezers

54. 3.NON-CRITICAL INSTRUMENTS
• They are equipment and surfaces that contact
only intact skin.
• They are cleaned and disinfected.
• Example: Spatula, mixing slab, protective eye
wear,Articulators and face bow,Mixing bowls
and spatulas.
• Shade and mould guides: if disinfected with
iodophor, wipe immediately with alcohol or
water to prevent discoloration.

55. • They are classified as critical instruments.
• Diamond and carbide burs:
0.2% gluteraldehyde and sodium phenate (Eg. Sporicidin) for at
least 10 minutes, cleaned with a bur brush or in an ultrasonic
bath. Sterilize in an autoclave or dry heat sterilize after cleaning.
• Steel burs:
May get damaged by autoclaving. Can be sterilized by using a
chemical vapor sterilizer or glass bead sterilizer at 2300C for 20-
30 seconds.
INSTRUMENTS STERLIZATION :
1.BURS :

56. 2.MOUTH MIRRORS :
• Dry heat or chemical vapor sterilization.
3.POLISHING WHEELS :
• Ethylene oxide sterilization.
4.STONES (DIAMOND, POLISHING, SHARPENING) :
• Dry heat, chemical vapor pressure autoclave.

57. 5.Hand piece :
• UK (BDA): sterilized in an autoclave.
• USA (CDC): recommends routine sterilization between patients,
but as not all handpieces can be sterilized, it should be flushed,
cleaned and then disinfected with a chemical disinfectant.
6.Visible light curing units :
• Disinfected with a phenolic disinfectant after use.
• Plastic units should be disinfected with iodophor.
• Gluteraldehyde disinfectants are not recommended as they have
been found to damage glass rods in the fibre-optic light tip, with
subsequent reduction in light output.

58. 7.Bite blocks and prosthesis at try-in stage :
• Immerse in sodium hypochlorite (5.25%) diluted
to 1:10 for 10 minutes for disinfection.
• Disinfect bite blocks returned from laboratory
before fitting and after fitting before returning
to the laboratory.
8.impression trays:
• Steel trays are sterilized via autoclave,chemical
vapor or dry heat and disinfected by ethylene
oxide.

59. 8.Impressions :
• They have been found to be contaminated on arrival from
laboratories. Casts poured from non-disinfected impressions too
have been shown to contain micro-organisms.
• ADA states to rinse impressions to remove saliva, blood and debris
and then to disinfect before sending to laboratory.
• Immersion has been preferred to spraying as it is based on the
assumption that it is more likely to assure exposure of all surfaces of
impression to disinfectant.
• Spraying disinfectant reduces chance of distortion, especially for
alginate, agar and polyether materials, but may not cover areas of
undercut adequately.

60. •Various methods used to disinfect impression materials :

61. 9.Sterilization of implants
• Gamma radiation.
• A Pyrex test tube sealed with a cotton roll can serve
as a sterilization vehicle for reusable dental implant
instruments and components.
The Journal of Prosthetic Dentistry, 2000;84

62. 10.Disinfection of dentures
• Hardness, flexural strength and color
stability of denture base resins is
significantly affected by disinfection
solution such as gluteraldehyde,
chlorohexidine, alcohol based, phenolic
based and hypochlorite disinfectants.
• Microwave irradiation for 6 min at 650 W
is used for denture disinfection.

63. CROSS INFECTION CONTROL IN
DENTAL LABORATORY

64. • All items to be sent to the dental
laboratory should be disinfected.
• They should be labelled, indicating the items have been
disinfected using an acceptable disinfection routine. This will
avoid duplicating disinfection procedures that may damage
materials.
• All materials returned from the laboratory to the dentist
should also be disinfected prior to insertion.

65. RECEIVING AREA:
• All items received from dental offices are placed in this area.
• They are unpacked using protective barriers and the packaging
disposed as contaminated medical waste.
• If the item received has not been notified as disinfected, it should
be disinfected with the routine procedures.
• Receiving area is thoroughly disinfected after each case using a
surface disinfectant.

66. CASTING IMPRESSIONS:
• In cases where impressions are carefully disinfected, precautions to
prevent contamination of casts are unnecessary.
• Alternatives to disinfecting impressions are:
 Spraying of stone models with iodophor or sodium hypochlorite prior
to handling. Or the cast may be soaked in 5.25% sodium hypochlorite
saturated with dental stone for 1 hour.
 Disinfectant may be added to the gauging liquid.
• Microwaves are unacceptable for sterilizing dental casts.

67. SPECIAL PRECAUTIONS WHEN HANDLING USED PROSTHESIS:
• Acrylic prosthesis worn for some time are porous and grinding the
surface may expose micro-organisms that have not been subjected to
disinfection.
• Wear gloves when grinding old acrylic.
• US National Association of Dental Laboratories suggests having a
disinfectant at lathe side for immediate disinfection following
exposure by grinding of previously worn prosthesis.

68. Regulated and General Waste
• Unless waste generated in the dental laboratory (e.g.
disposable trays or impression materials) falls into the
category of regulated medical waste, these materials can be
disposed of in standard waste containers.
• All disposables that can be considered “sharps” items (e.g.
orthodontic wire, blades, burs, etc.) should be disposed of in
appropriate containers designated as “sharps” disposable
containers or in puncture resistant containers.

70. 1. Dental clinic modification
A. Reception/Waiting area :
• Display visual alerts at the entrance of the clinic and reception.
• Ask them to wash their hands using hand wash or alcohol-based
hand rub.
• Include temperature recordings as part of your routine patient
assessment before performing any dental procedure.
• Maintain social distancing.
• Avoid usage of commercial split/centralized/window air
conditioners unless.

71. B. Operatory Area :
• Installation of high vacuum extra oral suction devices
recommended.
• Maintain natural air circulation within the operatory, through
frequent opening of windows and by using an exhaust blower to
extract the room air into the atmosphere.
• A strong exhaust fan is recommended to create a unidirectional
flow of air away from the patient.
• The window air condition system/split AC should be frequently
serviced, and filters cleaned. Commercially available electrostatic
air conditioner filters can be used.

72. 2. Protocols for Dental Patient Management:
A. Dental Health Care Professional Guidelines :
• Strict adherence to hand hygiene protocols should be followed.
• The highest level of PPE, i.e., gloves, gown, goggles, face shields,
and an N95 or higher-level respirator must be used during
emergency dental care.
B. Preprocedural Modifications :
• Drape the patient preferably with single-use, disposable plastic
apron.
• Use of preprocedural mouth rinse.

73. C. Management of resolved COVID-19 patients :
• The emergency dental care for resolved COVID-19 patients is
decided using two strategies:
1.Nontest-Based-Strategy:
• At least 3 days (72 h) have passed since recovery (resolution of
fever without the use of fever-reducing medications and
improvement in respiratory symptoms such as cough or shortness
of breath) and at least 7 days have passed since symptoms first
occurred.
2.Test-Based-Strategy:
• Symptomatic COVID-19 patients: Resolution of fever without the
use of and negative results from at least two consecutive
nasopharyngeal swab specimens collected ≥24 h apart.

74. SUMMARY
• Though many suggestions and specifications and methods are
recommended for sterilization and infection control, but the
real skill lies in analysis of a method which requires minimum
of a prosthodontist’s time, it is cost effective and requires no
extra skill or staff for performing the routine procedures.
• Each dental office is different in design and equipment. The
procedures for sterilization and disinfection should be
modified to suit an individual’s requirement.

75. REFERENCES
1) BDA “Infection control in dentistry”. British Dental Association Advice Sheet A12
June(1996) pp 4-18 &23.
2) Kumar GA, Mohan R, Prasad Hiremutt DR, Vikhram KB. COVID-19 pandemic and safe
dental practice: Need of the hour. J Indian Acad Oral Med Radiol 2020;32:164-71.
3) Ananthnarayan and Jayaram Paniker: Text book of microbiology: sterilization and
disinfection; fourth edition; 1990.
4) Burke FJ, Wilson NH: The use of gloves in cross infection control. A historical note. British
dental journal.166 (11): 426-428, 1989 June
5) Charles G. Maurice: A critical survey of the methods of instrument disinfection and
sterilization. Journal of American Dentistry, 1955; 55:527-544.
6) Joseph R Cain, Donald L: Sterilization of reusable impant components: A pilot study. J
Prosth Dent, 2000.

76. Thank you…