This document discusses infection control procedures in dentistry. It covers various elements of an infection control protocol including patient evaluation, personal protection, instrument cleaning and sterilization, use of disposables, disinfection, waste disposal, and staff training. Specific topics covered in detail include personal hygiene, clinic clothing, barrier protection, immunizations, sterilization methods, disinfection techniques, and various disinfecting agents commonly used in dentistry such as alcohols and aldehydes.

1. INFECTION
CONTROL
Prepared by Dr. Iyad Sunna

2. INFECTION CONTROL
PROCEDURES IN DENTISTRY

3. There are a number of elements in a comprehensive infection
control protocol:
• Patient evaluation
• Personal protection
• Instrument-cleaning and sterilization
• Use of disposables
• Disinfection
• Disposal of waste
• Staff training, including continuing education.
Infection control: specific practical features

4. A thorough medical history should be taken from each patient and updated at each
recall visit. It is not only good clinical practice but may also reveal disease that is
important in relation to cross infection and relevant to the dental procedure to be
undertaken.
Patient Evaluation

5. This subject is dealt with under the following headings:
• Personal hygiene
• Clinic clothing
• Carrier protection (gloves, eye shield, face masks, rubber dam isolation)
• Immunization procedures.
Personal Protection

6. The personal hygiene of all members of staff who are either directly or indirectly in
contact with patients should be scrupulous.
Staff should keep their hands away from their eyes, nose, mouth and hair, and avoid
touching sores or abrasions.
Cover cuts and bruises on fingers with dressings because they serve as easy portals for
pathogens.
Hair should be kept short or tied up, or a hair net should be worn.
Personal Protection: Personal Hygiene

7.  Hand Care:
Fingers are the most common vehicles of infection transmission. The whole dental team should
pay attention to meticulous hand care:
• Keep fingernails short and clean. Jewelry such as rings should be removed as rings tend to
entrap organisms and damage gloves.
• Thoroughly wash the hands before and after treating each patient using a proprietary
antimicrobial handwash (e.g. chlorhexidine gluconate) before putting on gloves. Hands should
also be washed before leaving the surgery for any purpose and upon return.
• A good hand-washing technique, should be developed by all staff so that all areas of the hands
are washed.
• Any obvious cuts or abrasions must be covered with adhesive waterproof dressings.
• Hands should be dried thoroughly using disposable paper towels, and gloves should be worn as
the last step before treatment
Personal Protection: Personal Hygiene

8. Hand Care:

9. A freshly laundered uniform or overgarment should be worn by all clinical personnel.
Garments should be changed at least daily.
Renewable overgarments should be washed at an appropriate temperature in a well-
maintained washing machine. Grossly contaminated clothing should be dealt with
separately.
Wear overgarments only in the clinic premises, not in corridors, canteens or lifts.
Personal Protection: Clinic Clothing

10. In order to minimize further the spread of organisms from staff to patients (and vice
versa), the following protective barriers should be used:
• Gloves
• Eye shields
• Face masks
• Rubber dam.
Personal Protection: Barrier Protection

11.  Gloves:
All dentists and close support personnel should routinely wear disposable latex or vinyl gloves.
The efficacy of gloves greatly diminishes if they are perforated. As gloves may perforate during
surgical procedures, it is advisable to change gloves at least hourly during long operative
procedures on the same patient.
Rarely, allergic reactions to gloves may develop in staff or patients. Skin creams, a spray-on
microfilm on the skin or a cotton glove liner may help these individuals.
Personal Protection: Barrier Protection

12.  Gloves:
There are three main types of gloves used in dentistry: their different uses should be clear:
1. Clean, high quality, protective latex gloves should be used whenever examining a patient’s
mouth or providing routine dental treatment when no bloodletting procedures are undertaken
2. Sterile gloves should be used for surgical procedures or procedures that may lead to blood-
letting. The wearing of two pairs of gloves during oral surgical procedures leads to a lower
frequency of inner glove perforation.
3. Heavy duty utility gloves should be used for cleaning instruments or surfaces or handling
chemicals.
Personal Protection: Barrier Protection

13.  Eye Shield:
Eye shields should be worn by dentists and close support personnel during all
procedures to protect the conjunctivae from spatter and debris generated by high-
speed handpieces, scaling (manual or ultrasonic), and polishing and cleaning of
instruments:
• Eyewear and face shields should be cleaned regularly.
• It is preferable to use eyewear with side protection.
• A supine patient’s eyes should always be protected.
Personal Protection: Barrier Protection

14.  Face Mask:
Wearing a face mask, such as a surgical mask, is a necessary hygienic measure,
particularly during high-speed instrumentation, as it prevents inhalation of
contaminated aerosols that might lead to both upper and lower respiratory tract
Infections.
Always ensure that masks are well adapted so that the nose and mouth are completely
covered.
Masks should not be touched with gloves during treatment or worn outside the
treatment zone.
Personal Protection: Barrier Protection

15.  Rubber Dam:
Rubber dam should be used in operative procedures to minimize saliva and blood-
contaminated aerosol production. Use of a rubber dam during operative procedures:
• Provides a clear visual field .
• Minimizes instrument contact with the mucosa
• Reduces aerosol formation.
Personal Protection: Barrier Protection

16. Practitioners should have a written policy on the vaccination (including administration
of boosters) of all staff and maintain an up-to-date immunization record of themselves
and their staff.
In the UK, vaccination against hepatitis B virus, tuberculosis and rubella (for women)
has been recommended for clinical dental staff, in addition to routine immunization
against tetanus, poliomyelitis and diphtheria. In the USA, immunization against all the
conditions listed, except tuberculosis and influenza, is recommended.
Personal Protection: Immunization procedures.

17. Vaccines available to dental personnel:
 Bacille Calmette–Guérin vaccine
Active against Mycobacterium tuberculosis. The vaccine contains live Mycobacterium
bovis.
Killed vaccines do not produce the cell mediated immune response essential for
protection against tuberculosis.
Indications:
All children between their 10th and 14th birthdays.
Personal Protection: Immunization procedures.

18.  Poliomyelitis vaccine
Live poliovirus types 1, 2 and 3 – Sabin vaccine (used in the UK) or killed poliovirus –
Salk vaccine.
Indications :
All infants, after 3 months.
Personal Protection: Immunization procedures.

19.  Measles–mumps–rubella vaccine
Live-attenuated strains of measles, mumps and rubella viruses.
Indications:
All children in the second year of life.
Personal Protection: Immunization procedures.

20.  Triple vaccine: diphtheria–tetanus–pertussis
Three-in-one vaccine for prevention against diphtheria caused by Corynebacterium
diphtheriae, whooping cough caused by Bordetella pertussis and tetanus caused by
Clostridium tetani. Contains killed B. pertussis and diphtheria and tetanus toxoid.
Indications:
All infants.
Personal Protection: Immunization procedures.

21.  Tetanus toxoid
The toxin of C. tetani that has been formol-treated.
Indications
Active immunization of the entire population. Although the disease is rare, tetanus can
develop after very trivial wounds.
Personal Protection: Immunization procedures.

22.  Hepatitis B vaccine
Indications
All health care workers who are at special risk, including dentists, dental hygienists,
dental surgery assistants, medical laboratory workers and those handling blood
products.
• Particular concerns for health care workers are blood-borne viral infections,
including hepatitis B and C, and human immunodeficiency virus (HIV) infection.
Hepatitis B infection used to be about 10 times more common among dental health
care workers than the public, but with the advent of the extremely effective
hepatitis B vaccine, this danger is minimal.
Personal Protection: Immunization procedures.

23.  Hepatitis B vaccine
The average risks of transmission of these diseases after percutaneous exposure to
blood are:
• HIV: 0.3%
• Hepatitis C: 1.8%
• Hepatitis B (HBsAg-positive): 6.0%
• Hepatitis B (hepatitis B e antigen (HBeAg)-positive): 30.0%
Thus, hepatitis B is most infectious and the least infectiousin this context is HIV.
Personal Protection: Immunization procedures.

24. Sterilization is a process that kills or removes all organisms (and their spores) in a
material or an object.
Disinfection is a process that kills or removes pathogenic organisms in a material or an
object. excluding bacterial spores, so that they pose no threat
of infection.
Antisepsis is the application of a chemical agent externally on a live surface (skin or
mucosa) to destroy organisms or to inhibit their growth. Thus, all antiseptics could be
used as disinfectants, but all disinfectants cannot be used as antiseptics because of
toxicity.
Instrument-cleaning and sterilization

25. In dentistry, sterilization is usually achieved by one of three methods:
1. Moist heat (steam under pressure in an autoclave)
2. Dry heat (hot-air oven)
3. Gaseous chemicals (chemiclave).
Sterilization

26.  Moist heat (steam under pressure in an autoclave)
When water is heated in a closed environment, its boiling point is raised, together with
the temperature of the generated steam; for example, at 15 psi, the steam temperature
is 121°C. This phenomenon is utilized in steam sterilization by the autoclave.
Sterilization

27.  Moist heat (steam under pressure in an autoclave)
There are two types of autoclaves:
1. Pre-vacuum autoclaves (porous load autoclaves), in which air is evacuated from a
metal chamber by vacuum suction. These, mainly used in central sterile supply units in
hospitals, are now becoming popular in dentistry due to wide availability as small,
bench-top units.
2. Gravity displacement autoclaves are small, automatic bench-top autoclaves. These
used to be very popular in dentistry, but they are not recommended now.
Sterilization

28.  Dry heat (hot-air oven)
Dry heat penetrates less well and is less effective than moist heat; consequently, higher
temperatures and longer times are required for sterilization. The total time for heating
up, holding and cooling may be several hours.
Dryheat sterilizers used in dentistry include static-air and forcedair types:
• The static-air type (oven-type). Here, the heating coils in the bottom or sides of the
unit cause hot air to rise inside the chamber through natural convection.
• The forced-air type (rapid heat-transfer sterilizer). Heated air is circulated throughout
the chamber at a high velocity, permitting more rapid transfer of energy from the air
to the instruments, thereby reducing the time needed for sterilization.
Sterilization

29.  Gaseous chemicals (chemiclave).
A combination of formaldehyde, alcohols, acetone, ketonesand steam at 17 psi serves
as an effective sterilizing agent.
Microbial destruction results from the dual action of the toxic chemicals and the heat.
In general, chemical vapor units sterilize more slowly than autoclaves (30 min versus
15–20 min, for packaged instruments) but are faster than hot-air ovens. The usual
temperature and pressure combinations are 127–132°C at 138–176 kPa for a period of
30 min, once the correct temperature has been attained.
This process cannot be used for materials or objects that can be altered by the
chemicals or are made of heat-sensitive material. Rusting is unusual if instruments are
dried before sterilization. The major advantages of the chemiclave are that it is faster
than dry-heat sterilization, it does not corrode instruments or burs.
Sterilization

30. Sterilization

31. Disinfection
Methods of disinfection consist of:
• Heat (pasteurization; boiling in water)
• Physical methods (ultrasonics)
• Chemical methods.

32. Disinfection
 Disinfection by heat
Pasteurization
Pasteurization is a process were heating prevents the spoilage of milk by selective
killing of unwanted microbes.
It should be noted that pasteurization is not a sterilization process.
Boiling water
If the boiling period is short, bacterial spores can survive; boiling water is therefore
inadequate for sterilization of dental instruments.

33. Disinfection
 Disinfection by heat
Physical methods: ultrasonics
Ultrasound is an effective way of disrupting microbial cell membranes and is used for
removing debris before autoclaving.
Chemical methods
Choosing a chemical disinfectant should be done carefully because a disinfectant used
for one purpose may not be equally effective for another. Further, the antimicrobial
activity of a chemical disinfectant falls drastically in the presence of organic debris.

34. Disinfection
 Mode of action of chemical disinfectants
The chemicals used as disinfectants generally behave as ‘protoplasmic poisons’ in three
different ways:
1. Disinfectants damage the bacterial cell membrane, examples are chlorhexidine,
quaternary ammonium compounds, alcohols and phenols.
2. Fixation of the cell membrane and blockage of egress of cellular components appears
to be the mode of action of formaldehyde and glutaraldehyde.
3. Oxidizing agents oxidize cellular constituents; examples are halide disinfectants such
as hypochlorite and bromides

35. Disinfection
 Conditions determining the effectiveness and choice of a disinfectant
Spectrum of activity
Disinfectants vary widely in their activity; e.g. some are more active against Gram-
positive than Gram-negative bacteria.
Satisfactory contact
All contaminated surfaces should come into contact with the disinfectant for the
specified period. Organic debris, air and greasy material may prevent this, hence the
importance of thorough cleaning of the material or instrument before disinfection.
Concentration
Adequate concentration of disinfectants is essential.

36. Disinfection
 Conditions determining the effectiveness and choice of a disinfectant
pH
The activity of a disinfectant is often pH-dependent (e.g. glutaraldehydes act only at
alkaline pH, whereas phenols work best at acid pH).
Neutralization
A wide range of substances, including hard water, soaps and detergent, may neutralize
the disinfectant.
Stability
Not all disinfectants are stable, especially when diluted, and may deteriorate with age
or storage. Solutions should be freshly prepared for use and marked with an expiry
date.

37. Disinfection
 Conditions determining the effectiveness and choice of a disinfectant
Speed of action
In general, disinfectants act slowly, and their activity depends on the concentration
used. Hypochlorites have a rapid action but are corrosive at high concentrations.
Glutaraldehyde is slow-acting but is an effective poricidal agent.
Absence of odour and toxicity
These attributes are desirable for disinfectants used in dentistry.

38. Disinfection
 Potency of disinfectants and their uses
• High-level disinfectants are active against Gram positive and Gram-negative bacteria,
spores and M. tuberculosis.
• Intermediate-level disinfectants destroy M. tuberculosis, vegetative bacteria, most
viruses and fungi, but few, if any, spores.
• Low-level disinfectants kill most bacteria and most fungi, but not M. tuberculosis or
spore.

39. Disinfection
 Disinfectant and antiseptic agents commonly used in dentistry
Alcohols
Ethyl alcohol or propyl alcohol (70%) in water is useful for skin antisepsis. Alcohol
combined with aldehydes is used in dentistry for surface disinfection.
Disadvantages are its flammability, limited sporicidal activity and ready inactivation by
organic material. Yet, alcohols are still popular because they are cheap, readily available
and water-soluble.

40. Disinfection
 Disinfectant and antiseptic agents commonly used in dentistry
Aldehydes
Glutaraldehyde is perhaps the most popular disinfectant used in dentistry in some
regions, whereas it is banned in others. It is both a skin irritant and a sensitization
agent, which results in both long-term and short-term health effects. It is mainly used
for so-called ‘cold sterilization’ or the high-level disinfection of equipment (such as
fibre-optic instruments) that does not withstand autoclaving procedures. All aldehydes
are high-potency disinfectants.
The free aldehyde groups of glutaraldehyde react strongly with the free amino groups
of proteins in a pH-dependent manner. This leads to the effective microbicidal activity,
sensitization of skin and incidentally, cross-linking with proteins such as collagen when
used as a component of dentine-bonding systems.

41. Disinfection
 Disinfectant and antiseptic agents commonly used in dentistry
Aldehydes
Hence, as the pH decreases, the activity of glutaraldehyde declines while its stability
increases. Conversely, when the pH is alkaline, the activity is higher and it becomes less
stable. Hence, in practice, glutaraldehyde is commercially available as a 2% acidic
solution, to which an ‘activator’ has to be added to bring the solution to the ‘in-use’
alkaline pH of 8.0. Although the activated solution has a shelf-life of up to 14 days.

42. Disinfection
 Disinfectant and antiseptic agents commonly used in dentistry
Bisguanides
Chlorhexidine is an example of a bisguanide disinfectant; it is widely used in dentistry
as an antiseptic and a plaque controlling agent. For example, a 0.4% solution in
detergent is used as a surgical scrub; 0.2% chlorhexidine gluconate in aqueous solution
is used as an antiplaque agent (Corsodyl); and at a higher concentration (2%), it is used
as denture disinfectant. It is highly active against both Gram-positive and Gram
negative organisms. It also kills Candida (but not M. tuberculosis).

43. Disinfection
 Disinfectant and antiseptic agents commonly used in dentistry
Halogen compounds
Hypochlorites and povidone–iodine are oxidizing agents and act by releasing halide
ions. Although cheap and effective,
they readily corrode metal and are quickly inactivated by organic matter. Examples
(Chloros, Domestos and Betadine.)
Phenolics
Phenolic disinfectants are clear and soluble. They do not irritate the skin and are used
for gross decontamination because they are not easily degraded by organic material.
They are poorly virucidal and sporicidal. Most bacteria are killed by these agents.
Examples are Clearsol and Stericol.

44. THANK
YOU
Dr. Iyad Sunna