infection control iyad

INFECTION CONTROLPrepared by Dr. Iyad Sunna

INFECTION CONTROL PROCEDURES IN

DENTISTRY

There are a number of elements in a comprehensive infectioncontrol 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

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

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

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

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

Hand Care:

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

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

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.


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.


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.


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 tractInfections.

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.


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.


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 themselvesand 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.

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.


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.


Measles–mumps–rubella vaccine

Live-attenuated strains of measles, mumps and rubella viruses.

Indications:All children in the second year of life.


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.


Tetanus toxoid

The toxin of C. tetani that has been formol-treated.

IndicationsActive immunization of the entire population. Although the disease is rare, tetanus can develop after very trivial wounds.


Hepatitis B vaccine

IndicationsAll 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.


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.


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 threatof 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

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

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

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

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

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

Sterilization

Disinfection

Methods of disinfection consist of:

• Heat (pasteurization; boiling in water)• Physical methods (ultrasonics)• Chemical methods.

Disinfection Disinfection by heat

PasteurizationPasteurization 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 waterIf the boiling period is short, bacterial spores can survive; boiling water is therefore inadequate for sterilization of dental instruments.

Disinfection Disinfection by heat

Physical methods: ultrasonicsUltrasound is an effective way of disrupting microbial cell membranes and is used for removing debris before autoclaving. Chemical methodsChoosing 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.

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

Disinfection Conditions determining the effectiveness and choice of a disinfectant

Spectrum of activityDisinfectants vary widely in their activity; e.g. some are more active against Gram-positive than Gram-negative bacteria.

Satisfactory contactAll 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.

ConcentrationAdequate concentration of disinfectants is essential.


pHThe activity of a disinfectant is often pH-dependent (e.g. glutaraldehydes act only at alkaline pH, whereas phenols work best at acid pH).

NeutralizationA wide range of substances, including hard water, soaps and detergent, may neutralize the disinfectant.

StabilityNot 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.


Speed of actionIn 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 toxicityThese attributes are desirable for disinfectants used in dentistry.

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.

Disinfection Disinfectant and antiseptic agents commonly used in dentistry

AlcoholsEthyl 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.


AldehydesGlutaraldehyde 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.


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.


BisguanidesChlorhexidine 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).


Halogen compoundsHypochlorites 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.) PhenolicsPhenolic 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.

THANK

YOU Dr. Iyad Sunna

infection control iyad

Health & Medicine