This document discusses infection control procedures in operative dentistry. It begins by outlining the risks of transmission of infectious diseases in dental settings due to contact with blood, saliva, and aerosols produced during procedures. It then describes various methods of microbial contamination including airborne, direct contact, indirect contact, cross-infections, and vulnerabilities of both patients and dental personnel. The document provides details on controlling different forms of contamination and outlines sterilization and disinfection procedures for dental instruments and the operatory environment. It emphasizes the importance of personal protective equipment, sterilization monitoring, and maintaining asepsis.

1. S. MANEESH AHAMED
FINAL YEAR PART 1
ROLL .NO: 12

2. • Pervasive increase in serious transmissible diseases over the last few
decades have created global concern and affected the treatment
approach of health care practitioners all over the globe.
• Every health care speciality that involves contact with mucosa, blood,
or blood contaminated body fluids should be regulated for the
prevention of transmission of certain infective diseases.

3. • Operative dentistry in its prime objective to provide the highest
standard of care, emphasis on ensuring maximum protection
against infectious diseases.
• In Operative dentistry, we generally deal with ambulatory,
relatively healthy patients who may carry many infectious
diseases unknowingly. Also, the dentist or any member or staff
may be suffering from some infection.
• It is therefore essential that all members of the dental team have
a clear understanding of infection transmission and various
methods of controlling the same.

4. Microbial exposures in the dental operatory include :
1. Air-borne contamination
2. Direct contamination of surfaces
3. Indirect contamination of surfaces.
4. Cross-infections
5. Patient vulnerability
6. Personal vulnerability.
 To comprehend the problem of microbial contamination that
confronts dentistry, it is necessary to examine the dental
treatment environment.

5. AIR-BORNE CONTAMINATION
• A high speed handpiece is capable of producing air-brone
contaminants from bacterial residents in the dental unit water
spray system and from microbial contaminants from saliva, tissues,
blood, plaque, and fine debris cut from carious teeth.
• Air borne contaminants exist in 3 forms; with
respect to the particle size :
1. AEROSOLS :
• Particle size ranges from 50 mm to 5 mm.
• Remain suspended in the air and breathed for
hours.
• They may carry agents of respiratory infection
borne by the patient.
• Aerosols produced by the cough of a patient with
unrecognized active pulmonary or pharyngeal
tuberculosis are likely to transmit the infection.

6. 2. MIST :
• Consist of particles that approach or exceeds 50mm in
size
• They usually become visible in a beam of light .
• Heavy mists tend to settle gradually from the air after 5
to 15 minutes.
• Combined with Aerosol, mists can also transmit
respiratory infections like tuberculosis.
3. SPLATTER :
• Consist of particles generally larger than 50 mm and even
visible splashes.
• They have a distinct trajectory, usually falling within 3ft of
the patient’s mouth,
• have the potential for clotting the face and outer garments
of the attending personnel.
• Splatter or splashing of mucosa is considered a potential
route of infection for dental personnel by blood – borne
pathogens.

7. CONTROL MEASURES :
• Use masks, protection eyewear, gloves, and gowns.
• Pre-treatment mouth rinse
• Rubber dam, high velocity air evacuation.
• Adequate air circulation
• Masks should be kept in place until air exchange in
the room has occurred or until personnel leave the
operatory.
DIRECT CONTAMINATION
• Direct contamination occurs when there is
direct contact with body fluids.
• This is a major exposure concern for dental
personnel.

8. INDIRECT CONTAMINATION
• With saliva-contaminated hands, the hygienist, dentist, and
assistant could repeatedly contact or handle unprotected operatory
surfaces during treatments.
• The invisible trail of saliva left on such contaminated surfaces
often defies either awareness or effective clean up.
• Moreover, it may act as a source of cross-contamination of patients.
• Items or areas which usually get contaminated include handpieces,
unprotected lamp handles, air-water syringe handle, control
switches on the patient’s chair etc.
CONTROL MEASURES
• Barrier protection of personal and equipment,
proper instrument sterilization.
• Methods of avoiding direct contact with
various surfaces are required.

9. CROSS-INFECTIONS
• Infected patients who are usually unaware of their infection go
elsewhere for diagnosis and treatment of oral and non-oral
conditions.
• Infection outbreaks are recognized in epidemiological studies where
they usually occur in clusters.
PATIENT VULNERABILITY
• Although infection risks for dental patients have not been as well
investigated as risks of hospital patients, they seem to be low.
• Nine cluster cases of dentist to patient transmission of HBV and one
cluster case of HIV have been documented since 1971.
• Since 1986, after the widespread implementation of infection control
practices no new cluster cases of HBV is reported.

10. PERSONNEL VULNERABILITY
• Dental personnel who is exposed to saliva, blood, and possible injury
from sharp instrumentation while treating patients are more
vulnerable to infections.
• Vulnerability of dental personnel before the institution of infection
control standards provide the best barometer of this.
• Proper immunisation and protective barriers are thus essential for
reducing the vulnerability to infections.

11. • HBV was the first infection disease to gain attention as a risk for
health care personnel
• HBV vaccine has curtailed HBV infection dramatically among dental
personnel who have been infectively immunised.
• Infection control procedures remain a major concern, however, to
prevent cross-infection among patients.
• In history, several cluster cases of HIV infection transmitted by
dental personnel have been reported. (Eg: Florida dentist, USA )
• Evidences indicates that the HIV infections from infected clinicians
took to patients could have been prevented by use of infection
control procedures.

12. • OSHA is a Federal regulatory agency under the US Department of
Labor.
• OSHA Blood borne pathogens program addresses control of
occupational exposure to blood and other potentially infectious
materials.
• It describes infection control as ‘Exposure control plan’.
‘Housekeeping’ is the term used to describe the clean up and
sterilization procedures.
• Several other terminologies introduced in OSHA regulations are
‘work practice controls’ and ‘engineering controls’. The term
‘personal protective equipment’ (PPE) is used for barriers such as
gloves, gowns, or masks.
• Only in dentistry is saliva considered a potentially infectious
material because oral manipulations and dental treatments
routinely cause saliva to become contaminated with the patients
blood.

13. ASEPSIS :
 The prevention of contact with pathogens. In dentistry this includes the
technique of barrier protection, sterilization and disinfection.
STERILIZATION :
 The destruction of all forms of life including the most heat resistant
bacterial spores. Practically, sterilization denotes the use of physical and
chemical agents to eliminate all viable microorganisms, including bacteria,
fungi, virus and spores.
DISINFECTION :
 The destruction of pathogenic agents by directly applied physical or
chemical means. Here spores are not destructed.
ANTISEPTICS :
 Agents that prevent the growth or action of microorganisms on living
tissues.
DISINFECTANTS :
 Chemicals capable of killing pathogenic organisms when applied to
inanimate objects.

14. • Spread of infection in a dental clinic occur either by direct inoculation
or inhalation.
• Infection control measures can be broadly categorized as follows:
1. PERSONAL BARRIER PROTECTION.
2. DISPOSAL OF CLINICAL WASTES.
3. STERILIZATION AND DISINFECTION.

15. GLOVES
• OSHA regulations specify that all clinical personnel must wear
treatment gloves during treatment procedures.
• Fresh gloves must be used for every patient.
• Torn or punctured gloves must be discarded immediately.
• Instead of acting as a barrier gloves worn for a longer periods can
harbor blood-borne and saliva-borne pathogens.
• Gloves must not be washed with hand soaps. Washing reduces glove
integrity, leaving personnel more vulnerable.
HANDWASHING
• Meticulous hand care can prevent the transmission of infections
to a major extend.
• At the beginning of the routine treatment period, the clinician
should remove watches, jewellery, and rings and wash the hands
with a suitable cleanser.
• Hands should be lathered for at least 10 seconds, rubbing all
surfaces, and rinsed.

16. • Hand cleansers having containing a mild antiseptic, such as 3%
parachlorometaxylenol (PCMX) or 4% chlorhexidine, are preferred
to control transient pathogens and to suppress overgrowth of skin
bacteria.

17. PROTECTIVE EYEWEAR, MASKS, AND HAIR PROTECTION
• Protective eye wear may consist of goggles or glasses with solid side
shields.
• A mask should be worn to protect against aerosols.
• Face shields are appropriate for heavy splatter, but masks are still
required to protect against aerosols that drift behind the shield.
• Eyewear is worn with a lean hand before gloving and removed after
the removal of gloves and hand washing.
• Masks should be grasped only by the strings or bands on its side or
back of the head to remove it.
• The mask should be changed between every patient or whenever it
becomes moist or visibly soiled.
• Masks with the highest filtration are rectangular, folded types used for
surgeries.
• Dome-shaped masks are adequate barriers against splatter and are
considered to prevent HBV and HIV infection.

18. PROTECTIVE OVERGARMENTS
• An overgarment must be protective of clothing and skin.
• Overgarments must be changed whenever becoming moist or visibly
soiled.
• Used overgarments require a minimum handling and must be
laundered easily.
• Wearing contaminated garments home or out of the clinical area
should not occur.

19. • Infected blood and other liquid clinical waste generally can be poured
down a sanitary sewer or drain designated for that purpose.
• Mercury, silver or other heavy metals are however should be disposed
separately.
• Contaminated material such as used masks , gloves, blood-soaked or
saliva-soaked cotton rolls, must be discarded safely.
• Pathologic waste, excised tissues require separate disposal and may not
be discarded into the trash.
• Needle disposal is done in a hard walled, leak proof, and sealed
container, which has biohazard label
• Judgement is essential in bagging medical waste so that injury or direct
contact with liquids does not occur because HIV and HBV can survive
beyond a few days while wet.

20. OPERATORY ASEPSIS
The dental operatory must be maintained spotlessly clean. The items
in the dental operatory can be categorized into three groups :
1. CRITICAL ITEMS : These include instruments that contact cut tissue
or those that penetrate the soft tissues. Eg : Needles, scalpels,
endodontic instruments.
2. SEMICRITICAL ITEMS : These include all instruments that enter the
patient’s mouth. These also include items attached to the dental
unit which are used intra-orally during treatment.
Eg: Air/water syringe tip, suction tips, hand pieces,
3. NON-CRITICAL ITEMS : These are environmental surfaces such as
chairs, benches, floors, walls and supporting equipments of the
dental unit which are not ordinarily touched during treatments.

21. PROCEDURES BEFORE STERILIZATION
1. PRESOAKING OF INSTRUMENTS : Contaminated instruments are kept
soaked in a chemical disinfectant like Gluteraldehyde or synthetic
phenol for 30 minutes. This will prevent blood and saliva from drying
on the instruments thus facilitating cleaning.
2. PRESTERILIZATION CLEANING OF INSTRUMENTS : After soaking the
contaminated instruments for some time, they must be thoroughly
cleaned before sterilization in order to remove gross organic debris,
blood and saliva.
Cleaning can be done by :
A. MANUAL METHOD : after wearing protective utility gloves the
instruments may be cleaned using a hard brush with stiff bristles
along with a detergent solution or using soap and water.
B. ULTRA SONIC METHOD : it is much more effective and safer than
hand cleaning. Presoaked instruments may be immersed in an
ultrasonic cleaner and kept in bath for 5 minutes.

22. • Pizoelectric cleaners operates at 40◦ C and 35 KHz frequency.
• The tank is usually filled with a detergent solution to increase
the effectiveness of cleaning.
• Ultrasonic cleaners employ pizoelectric oscillators situated
underneath stainless steel enclosures to create oscillations in a
fluid filled tank.
• The cavitation effect produces microscopic bubbles that
effectively clean inaccessible areas on instrument surfaces.

23. A. STEAM PRESSURE STERILIAZATION (AUTOCLAVE)
B. DRY HEAT STERILIZATION (DRYCLAVE)
C. CHEMICAL VAPOUR PRESSURE STERILIZATION (CHEMICLAVE)
D. ETHYLENE OXIDE (ETOX) STERILIZATION

24. • The steam autoclaving is the most commonly used
method of sterilization.
• Autoclaves uses super heated steam under
pressure which have high degree of penetration.
• Moist heat produced inside the autoclave kills
microorganisms by protein coagulation and
breakdown of DNA and RNA.
• The autoclave consist of a double walled chamber
to hold the instruments and the steam circulates
inside it under pressure.
• It is the most rapid and effective method of
sterilization.
STERILIZATION CYCLES
• Standard : 121◦C (250◦F), 15 lbs pressure for 15 minutes.
• Flash method : 134◦C (273◦F), 30 lbs pressure for 7-10 minutes.

25. TYPES OF AUTOCLAVES
1. DOWNWARD DISPLACEMENT AUTOCLAVES : They cause
downward displacement of air as steam enters the top of
the chamber. Their efficacy is low.
2. HIGH VACUUM AUTOCLAVES : They are also known as
rapid cycle autoclaves. In these, air is evacuated by
vacuum suction before steam enters the chamber. These
autoclaves perform rapid and effective sterilization than
conventional autoclaves and are presently popular in
dentistry.
DISADVANTAGES OF AUTOCLAVES
• Corrosion of carbon steel instruments and burs, steel neck
and shank of some diamond instruments and carbide burs.
• May damage plastic and rubber items
• Dulls unprotected cutting edges.

26. • This method effectively sterilizes instruments at high temperature above
160◦C
• The apparatus is a dry heat oven which has heated chambers to allow air
to circulate by gravity flow
• Dry heat kills microorganisms by an oxidation process
• It has less penetration capacity as compared to moist heat in autoclaves
• Burs and carbon steel instruments do not rust if they are well dried
before sterilization.
• Rapid cycles are possible at high temperatures in a dry heat oven.
STERILIZATION CYCLES
• Conventional dry heat oven : 160◦C for 90 minutes
• Mechanical convection oven : 320-375◦C for 6-12 minutes

27. • This method employs chemical vapour under pressure for
sterilization.
• The apparatus is similar to the autoclave but uses a mixture of
formaldehyde, alcohol, ketone, acetone, and water.
• When solution is heated under pressure it forms a gas that
sterilizes instruments.
• The chemical vapour kills microorganisms by destroying vital
protein systems.
• They does not corrode metals. Hand pieces however cannot be
sterilized by this method.
STERILIZATION CYCLE
• 131◦C (270◦F) under 20 lbs pressure for 20 minutes.

28. • This method uses automatic devices filled with ethylene oxide gas at
temperatures below 100C
• They are designed to sterilize complex instruments and delicate
materials.
• Ethylene oxide is highly penetrable and kills microorganisms by
chemically reacting with nucleic acids.
• The sterilization cycles takes several hours and once over, aeration for
24 hours or more is needed before the instruments can be used.
• A major concern about using this method is the potential mutagenic /
carcinogenic property of ethylene oxide gas.

29. MONITORING STERILIZATION
1. PROCESS INDICATORS : strips, tapes, tubes or paper marked
with special ink that change colour on exposure appropriate
sterilization cycle.
2. BIOLOGICAL INDICATORS : non pathogenic stains of microbial
spores in the form of strips. It is done on a weekly basis. Eg:
Bacillus stearothermophillus ( for Autoclaves) , Clostridium
sp (Hot air oven).

30. • Several newer methods of sterilization are
employed for specific purposes.
• Gamma rays are used to sterilize suture materials,
syringes, disposable needles and other heat
sensitive items.
• Ultraviolet light is used to purify air in the dental
operatory but is not very effective.
• Hydrogen peroxide vapour, Gas plasma
sterilization and the use of Lasers are still under
investigation but are not yet practical for
dentistry.

31. 1. Prior to the removal of hand piece from the dental unit,
clean it by wiping visible debris using a suitable
disinfectant such as alcohol.
2. Following this, run it for a minimum of 30 seconds to
discharge residual water and air.
3. Next, clean the hand piece thoroughly with a soap or
detergent solution.
4. Next, reattach hand piece to the unit and dry.
5. Lubricate the hand piece. (some manufacturers
recommend lubrication after sterilization)
6. Finally, place the hand piece in a paper pack and seal it.
7. Now the hand piece can be sterilized by autoclaving.

32. • They are used mainly for semi-critical and non-critical items
• Complete removal of all biologic forms of infective organisms
does not occur.
• Some viruses and bacterial spores are resistant to disinfection
procedures.
PHYSICAL METHOD – BOILING :
Boiling water at 98C to 100C for 10 minutes.
This method can be used to kill blood borne
pathogens. But they cause extensive rusting of
instruments.
CHEMICAL METHODS
Chemical agents like Gluteraldehyde, Sodidum
hypochlorite, Iodophores, Alcohols, Phenolics
and Quaternary ammonium compounds can be
used as disinfectants.

33. • Dental unit water lines may be contaminated by biofilm.
• Since biofilm is formed by the colonization and proliferation of
microorganisms, the water emitted by these water lines may contain
high concentration of microorganisms.
• While using handpieces and air/water syringes, these microorganisms
can be introduced into patients oral cavity.
METHODS TO REDUCE BIOFILM FORMATION IN WATER LINES
1. PERIODIC FLUSHING OF DENTAL UNIT WATER LINES : This is
done with sterile water or 1:10 dilution of 5.25% sodium
hypochlorite is recommended. A minimum of 20 to 30 seconds
of flushing o waterlines between patients is recommended.
2. USING FILTERS AND ANTIETRACTION VALVES : This is attached
to the waterline which prevent the retraction of fluid back into
the tubing.
3. USE OF STERILE WATER DELEVERY SYSTEMS

34. • Thoroughly wash the impression or other prosthetic items under
running tap water to remove saliva, blood and debris.
• Disinfect the surface of moist items including elastomeric impressions
by immersion in 2% Gluteraldehyde or chlorine compounds for 10
minutes.
• For alginate impressions, spray an Iodophor as soaking may distort the
impression
• Store the items in separate sealed plastic bags before transfer to the
laboratory.

35. Adequate asepsis is a highly critical step in treatment. Proper infection
control measures are very much essential for the prevention of spread of
serious infective diseases like TB, HBV, HIV etc. Personal barrier methods,
proper disposal of waste and proper sterilization and disinfection insures
adequate infection control in dental settings. Various personal barriers
are available which has to be properly used during treatment and
examination. Sterilization procedures used in dentistry should be simple,
effective and of relatively short duration so that there is a readily
available supply of sterile instruments and other materials. Disposal of
waste and other biohazard materials should also be properly executed.

36. • STURDEVANT’S ART AND SCIENCE OF OPERATIVE DENTISTRY – 5TH EDITION
• CLINICAL OPERATIVE DENTISTRY –PRINCIPLES AND PRACTICE