Sterilization & Cross Infection control in dental clinicsOmar Karadsheh

Guidelines for Infection Control in Dental Health-Care Settings—2003. MMWR 2003; Vol. 52, No. RR-17

Why Is Infection Control Important in Dentistry?

Both patients and dental health care personnel (DHCP) can be exposed to pathogens.

Contact with blood, oral and respiratory secretions, and contaminated equipment occurs.

Proper procedures can prevent transmission of infections among patients and DHCP.

During the provision of dental treatment, both patients and dental health care personnel (DHCP) can be exposed to pathogens through contact with blood, oral and respiratory secretions, and contaminated equipment.

Following recommended infection control procedures can prevent transmission of infectious organisms among patients and dental health care personnel.

Modes of transmission

Direct contact with blood or body fluids

Indirect contact with a contaminated instrument or surface

Contact of mucosa of the eyes, nose, or mouth with droplets or spatter

Inhalation of airborne microorganisms

Dental patients and DHCP may be exposed to a variety of disease-causing microorganisms that are present in the mouth and respiratory tract. These organisms may be transmitted in dental settings through several routes, including:

Intact or non-intact skin in direct contact with blood, oral fluids, or other potentially infectious patient materials.

Indirect contact with a contaminated object (e.g., instruments, operatory equipment, or environmental surfaces).

Contact of mucous membranes of the eyes, nose, or mouth with droplets (e.g., spatter) containing microorganisms generated (e.g., coughing, sneezing, talking) from an infected person and propelled a short distance.Inhalation of airborne microorganisms that can remain suspended in the air for long periods of time.

Chain of Infection

Pathogen

Source

ModeEntry

Susceptible host

Break the chain

Infection through any of these routes requires that all of the following conditions be present:

•An adequate number of pathogens, or disease-causing organisms, to cause disease.

•A reservoir or source that allows the pathogen to survive and multiply (e.g., blood).

•A mode of transmission from the source to the host.

•An entrance through which the pathogen may enter the host.

•A susceptible host (i.e., one who is not immune).

The occurrence of all these events is considered the “chain” of

infection. Effective infection control strategies prevent disease

transmission by interrupting one or more links in the chain of

infection.

Standard Vs. Universal Precautions

Universal precautions:

Include protection from all human blood and human blood components

Aims at protection of infection with blood-borne pathogens

Standard Precautions

Apply to all patients

Integrate and expand Universal Precautions to include organisms spread by blood and also

Body fluids, secretions, and excretions except sweat,

whether or not they contain bloodNon-intact (broken) skinMucous membranes

Previous CDC recommendations on infection control for dentistry (1986,

1993) focused on the use of Universal Precautions to prevent transmission

of bloodborne pathogens. Universal Precautions were based on the

concept that all blood and certain body fluids should be treated as infectious

because it is impossible to know who may be carrying a bloodborne virus.

Thus, Universal Precautions should apply to all patients.

The relevance of Universal Precautions applied to other potentially infectious

materials was recognized, and in 1996, CDC replaced Universal

Precautions with Standard Precautions. Standard Precautions integrate and

expand Universal Precautions to include organisms spread by:• Blood.• All body fluids, secretions, and excretions except sweat, regardless of whether

they contain blood.• Non-intact skin.• Mucous membranes.

Saliva has always been considered a potentially infectious material in dental

infection control; thus, no operational difference exists in clinical dental

practice between Universal Precautions and Standard Precautions.

Elements of standard precautions

Vaccination

Hand-washing

Use of gloves, masks, eye protection, and gowns

Environmental surfaces

Sterilization & Patient care equipment

Injury prevention

Vaccination against Blood-borne Pathogens

Preventing Transmission of Bloodborne Pathogens

Are transmissible in health care settings Can produce chronic infection Are often carried by persons unaware of their infection

Bloodborne viruses such as hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV)

Bloodborne viruses such as hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) are of concern to dental health care personnel (DHCP). These viruses:

• Can be transmitted to patients and health care personnel (HCP) in health care settings.

• Can produce chronic infection.

• Are often carried by persons unaware of their infection.

Potential Routes of Transmission of Bloodborne Pathogens

Patient DHCP

DHCP Patient

Patient Patient

Average Risk of Bloodborne Virus Transmission after Needlestick

Source Risk

HBVHBsAg+ and HBeAg+ 22.0%-31.0% clinical hepatitis;

37%-62% serological evidence of HBV infection

HBsAg+ and HBeAg- 1.0%-6.0% clinical hepatitis; 23%-37% serological evidence of HBV infection

HCV 1.8% (0%-7% range)

HIV 0.3% (0.2%-0.5% range)

This slide shows the average risk of transmission after a single needlestick

from an infected patient by type of bloodborne virus. As shown here, risk

varies greatly by type of virus.

For instance, the risk of HBV transmission after a percutaneous exposure

(e.g., needlestick) to HBV-infected blood varies from 1%– 62%, depending

on the hepatitis B e-antigen (HBeAg) status of the source patient. If the

source patient’s blood is positive for HBeAg (a marker of increased

infectivity), the risk of transmission can be as high as 62%. If the patient’s

blood is hepatitis B surface antigen (HBsAg) positive but HBeAg negative,

the risk varies from 1%– 37%.

The average risk of HCV transmission after a percutaneous exposure to

HCV-infected blood is 1.8%.

The average risk of HIV infection after a percutaneous exposure to HIV-

infected blood is 0.3%. To put this in perspective, 1 in 3 needlesticks from

an HBeAg+ source patient would result in infection compared to only 1 in

300 needlesticks from an HIV-infected patient.

Concentration of HBV in Body Fluids

High Moderate Low/NotDetectable

Blood Semen Urine Serum Vaginal Fluid Feces Wound exudates Saliva Sweat

Tears Breast

Milk

As mentioned earlier, one factor to consider in assessing the risk of infection is the type of body substances to which DHCP are exposed. This slide shows the concentration of HBV in various body fluids. On the left, in red, are the fluids with the highest concentration of virus.

Moving from the left to the right side, the concentration decreases. Blood, for instance, has a higher virus concentration than urine or sweat. Saliva alone, without blood, has a moderate concentration of virus.

Estimated Incidence of HBV Infections Among HCP and General Population, United States, 1985-1999

0

50

100

150

200

250

300

350

1985 1987 1989 1991 1993 1995 1997 1999

Year

Inci

denc

e pe

r 10

0,00

0

Health Care Personnel

General U.S. Population

In the early to mid-1980s, health care personnel (HCP) had a much higher incidence (i.e., the number of new infections each year) of HBV infection than the general population. By the early 1990s, however, the incidence among health care personnel had dropped below that found in the general population. This decrease likely is the result of increased use of Universal Precautions and the hepatitis vaccine.

Hepatitis B Vaccine

Vaccinate all DHCP who are at risk of exposure to blood

3-dose vaccine (0,1, and 6 months) Provide access to qualified health care

professionals for administration and follow-up testing

Test for anti-HBs 1 to 2 months after 3rd dose

Booster if if anti-HBs levels decrease below 10 mIU/mL

Both Occupational Safety & Health Administration (OSHA) regulations and CDC recommendations state that hepatitis B vaccine should be made available to all DHCP who are exposed to blood or other potentially infectious materials.

Employers should provide easy access to a qualified health care professional who can administer the vaccine and provide appropriate follow-up testing.

Post-vaccination testing for antibody to hepatitis B surface antigen (anti-HBs) response is indicated for DHCP who have blood or patient contact and are at ongoing risk for injuries with sharp instruments or needlesticks. Post-vaccination testing should be completed one to two months after the 3rd vaccine dose. Knowledge of antibody response should guide appropriate postexposure prophylaxis.

Characteristics of Percutaneous Injuries Among DHCP

Reported frequency among general dentists has declined

Caused by burs, syringe needles, other sharps

Occur outside the patient’s mouth

Involve small amounts of blood

Among oral surgeons, occur more frequently during fracture reductions and procedures involving wire

Available information indicates that percutaneous injuries among dentists declined from an average rate of 11 injuries per year in 1987 to <3 injuries per year in 1993.

In general, most injuries among general dentists were caused by burs, followed by syringe needles and other sharp instruments. Injuries most often occur while the dentist’s hands are outside the patient’s mouth. Most injuries involve small, rather than large, amounts of blood.

The frequency of percutaneous injuries among oral surgeons is similar to that reported among U.S. dentists. Injuries among oral surgeons may occur more frequently during procedures using surgical wire, such as during fracture reductions.

Exposure Prevention Strategies

Engineering controls Work practice controls Administrative controls

Primary methods used to prevent occupational exposures to blood in health care settings include Standard Precautions, engineering controls, work practice controls, and administrative controls. Engineering controls that eliminate or isolate the hazard are the primary strategies for protecting DHCP and patients.

Where engineering controls are not available or appropriate, work practice controls that result in safer behavior and personal protective equipment (PPE) can prevent exposure.

Administrative controls are policies and procedures that reduce the risk of exposure to certain diseases, such as TB.

Engineering Controls

Isolate or remove the hazard Examples:Sharps containerMedical devices with injury protection features (e.g., self-sheathing needles)

Engineering controls reduce exposure either by removing, eliminating, or isolating the hazard from the worker. These controls are frequently technology based and often incorporate safer designs of instruments and devices.

Examples include the following:

•Sharps containers.

•Medical devices with injury protection features, such as self-sheathing needles and scalpels.

Work Practice Controls

Change the manner of performing tasks

Examples include:• Using instruments instead of fingers

to retract or palpate tissue

• One-handed needle recapping

Work practice controls are behavior based and are intended to reduce the risk of blood exposure by changing the manner in which a task is performed.

Examples include the following:

•Using instruments instead of fingers to retract or palpate tissue during suturing and administration of anesthesia.

•One-handed needle recapping.

•Not passing an unsheathed needle to another DHCP.

Administrative Controls

Policies, procedures, and enforcement measures

Placement in the hierarchy varies by the problem being addressedPlaced before engineering controls for airborne precautions (e.g., TB)

Administrative controls include policies, procedures, and enforcement measures to prevent exposure to disease-causing organisms.

The placement of administrative controls in the hierarchy of control measures varies by the problem or disease being addressed.

For example, for airborne organisms such as Mycobacterium tuberculosis, these controls rank before engineering controls. In this example, the early identification and referral of dental patients suspected of having TB is the most important prevention strategy.

Post-exposure Management Program

Clear policies and procedures Education of dental health care personnel (DHCP) Rapid access to

Clinical carePost-exposure prophylaxis (PEP)Testing of source patients/HCP

Despite our best efforts, blood exposures will likely continue to occur.

Post-exposure management remains an important component of a

complete program to prevent infection following exposure to blood.

Elements of an effective post-exposure management program include:

• Policies and procedures that clearly state how to manage exposures.

• Education of dental health care personnel in prevention strategies (including evaluation of safety devices), principles of post-exposure management, the importance of prompt reporting, and PEP efficacy and toxicity.

• Resources for rapid access to clinical care, post-exposure prophylaxis, as well as testing of both source patients and exposed health care personnel (preferably with a rapid HIV test).

[Comments: Except for institutional settings, coordination with off-site infection control or occupational health services likely will be necessary. A health care professional who is qualified to manage, counsel, and provide medical follow-up should be selected before staff are placed at risk. Ensure that this person is familiar with the dental application of risk assessment and management.]

Wound managementExposure reportingAssessment of infection riskType and severity of exposureBloodborne status of source personSusceptibility of exposed person

Post-exposure Management

The key elements of post-exposure management include wound management and exposure reporting.

The evaluating health care professional should assess the risk of infection by examining the type and severity of exposure, the bloodborne status of the source person, and the susceptibility (immune status) of the exposed person. All of these factors should be considered in assessing the risk of infection and the need for further follow-up (e.g., PEP).

Hand Hygiene

Why Is Hand Hygiene Important?

Hands are the most common mode of

pathogen transmission

Reduce spread of antimicrobial resistance

Prevent health care-associated infections

Next we turn to the subject of Hand Hygiene. So, is hand hygiene the single most important factor in preventing the spread of pathogens in health care settings?

First, hands are the most common mode of pathogen transmission.

Hand washing can reduce the spread of antibiotic resistance in health care settings and the likelihood of health care-associated infections.

[Additional comments: CDC estimates that each year nearly 2 million patients in the United States acquire infections in hospitals, and about 90,000 of these patients die as a result.]

Hands Need to be Cleaned When

Visibly dirty

After touching contaminated objects with bare hands

Before and after patient treatment (before glove placement and after glove removal)

CDC recommends that hands be cleaned:

•When they are visibly dirty.

•After touching contaminated objects with bare hands.

•Before and after patient treatment, that is, before glove placement and immediately after glove removal.

Photo credit: Centers for Disease Control and Prevention, Atlanta, GA.

Hand Hygiene DefinitionsHandwashing

Washing hands with plain soap and water

Antiseptic handwashWashing hands with water and soap or other detergents

containing an antiseptic agent

Alcohol-based handrubRubbing hands with an alcohol-containing preparation

Surgical antisepsis

Handwashing with an antiseptic soap or an alcohol-based handrub before operations by surgical personnel

Hand hygiene is a general term that applies to either handwashing, antiseptic handwash, alcohol-based handrub, or surgical hand hygiene/antisepsis.

•Handwashing refers to washing hands with plain soap and water.

• Antiseptic handwash refers to washing hands with water and soap or other detergents containing an antiseptic agent, such as triclosan or chlorhexidine.

• Using a waterless agent containing 60%–95% ethanol or isopropanol alcohol-containing preparation is referred to as an alcohol handrub. These agents are a new addition to the dental guidelines and have become more frequently used in the United States to improve compliance with handwashing in hospitals. In dental practices, however, sinks are readily available and the need for alcohol preparations is not as great.

•Surgical antisepsis refers to an antiseptic handwash or alcohol-based handrub* performed preoperatively by surgical personnel to eliminate microorganisms on hands. Antiseptic preparations for surgical hand hygiene should have persistent (long-lasting) antimicrobial activity.

* If using an alcohol-based handrub the hands should first be washed with soap and water.

Efficacy of Hand Hygiene Preparations in Reduction of Bacteria

Good Better Best

Plain Soap Antimicrobial soap

Alcohol-based handrub

Source: http://www.cdc.gov/handhygiene/materials.htm

Plain soap is good for reducing bacterial counts, but antimicrobial soap is better and alcohol-based handrubs are the best, providing activity that prevents or inhibits survival of microorganisms after the product is applied.

Alcohol-based Preparations

Rapid and effective antimicrobial action

Improved skin condition

More accessible than sinks

Cannot be used if hands are visibly soiled

Store away from high temperatures or flames

Hand softeners and glove powders may “build-up”

Benefits Limitations

This slide lists the benefits and limitations of alcohol-based

preparations.

• Alcohol handrubs have a rapid and effective antimicrobial action when applied to the skin but must contain other ingredients, such as chlorhexidine or triclosan, to achieve persistent (long-lasting) activity.

• When combined with emollients, or skin softeners, they can improve skin condition.

• In hospital settings, they are often more accessible than sinks.

However,

• Alcohol is not a good cleaning agent, so these products cannot be used if hands are visibly soiled.

• Because of their flammable nature, they must be stored away from high temperatures or flames.

• In addition, there is some concern that hand softeners and glove powders might build up on the hands after repeated use. Hands should be washed occasionally with soap and water.

Special Hand Hygiene Considerations

Use hand lotions to prevent skin dryness

Consider compatibility of hand care products with

gloves (e.g., mineral oils and petroleum bases may cause early glove failure)

Keep fingernails short

Avoid artificial nails

Avoid hand jewelry that may tear gloves

Hand lotions can prevent skin dryness associated with hand washing. However, it’s important to consider the compatibility of lotion and antiseptic products and the effect of petroleum or other oil emollients on the integrity of gloves when selecting and using them.

Short nails allow thorough cleaning of nails and may reduce premature glove tearing. Artificial nails can harbor pathogens—thus, their use should be avoided.

During surgical procedures, hand or arm jewelry can harbor microorganisms or increase risk of glove failure. If worn during non-surgical procedures, hand or arm jewelry can affect glove placement, fit, or durability.

Personal Protective Equipment

Personal Protective Equipment

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

Personal protective equipment (PPE), or barrier precautions, are a major component of Standard Precautions. Use of rotary dental and surgical instruments (e.g., handpieces, ultrasonic scalers) and air-water syringes creates a visible spray that contains primarily large-particle droplets of water, saliva, blood, microorganisms, and other debris. This spatter travels only a short distance and settles out quickly, landing either on the floor, operatory surfaces, dental health care personnel (DHCP), or the patient.

PPE is essential to protect the skin and the mucous membranes of DHCP from exposure to infectious or potentially infectious materials. PPE should be worn whenever there is potential for contact with spray or spatter and should be removed when leaving treatment areas.

Photo credit: Lt. Col. Jennifer Harte, U.S.A.F. Dental Investigation Service, Great Lakes, IL.

Masks, Protective Eyewear, Face Shields

Wear a surgical mask and either eye protection with solid side shields or a face shield to protect mucous membranes of the eyes, nose, and mouth

Change masks between patients

Clean reusable face protection between patients; if visibly soiled, clean and disinfect

A standard surgical mask that covers the nose and mouth is worn to protect the mucous membranes from spatter generated during dental procedures. Eye protection with solid side shields or a face shield should also be worn.

A mask should be changed between patients or if it becomes wet during patient treatment.

Clean reusable face protection with soap and water between patients; if visibly soiled, clean and disinfect.

Protective Clothing

Wear gowns, lab coats, or uniforms that cover skin and personal clothing likely to become soiled with blood, saliva, or infectious material

Change if visibly soiled

Remove all barriers before leaving the work area

DHCP should wear long-sleeved disposable or reusable gowns, lab coats, or uniforms that cover skin and personal clothing likely to become soiled with blood, saliva, or infectious material (e.g., when spatter and spray of blood, saliva, or other potentially infectious material to the forearms might occur).

DHCP should change protective clothing when it becomes visibly soiled or as soon as possible if penetrated by blood or other potentially infectious fluids.

All protective clothing should be removed before leaving patient care or laboratory areas.

Photo credit: Lt. Col. Jennifer Harte, U.S.A.F. Dental Investigation Service, Great Lakes, IL.

Gloves

Minimize the risk of health care personnel acquiring infections from patients

Prevent microbial flora from being transmitted from health care personnel to patients

Reduce contamination of the hands of health care personnel by microbial flora that can be transmitted from one patient to another

Are not a substitute for handwashing!

Wearing gloves does not eliminate or replace the need for hand washing. Hand hygiene should be performed immediately prior to putting on and after removal of gloves. Gloves might have small holes or tears that are not noticeable, or hands can become contaminated as gloves are removed. Such circumstances increase the risk of wound contamination and exposure of the DHCP’s hands to microorganisms from patients.

Recommendations for Gloving

Wear gloves when contact with blood,

saliva, and mucous membranes is

possible

Remove gloves after patient care

Wear a new pair of gloves for each

patient

A standard surgical mask that covers the nose and mouth is worn to protect the mucous membranes from spatter generated during dental procedures. Eye protection with solid side shields or a face shield should also be worn.

A mask should be changed between patients or if it becomes wet during patient treatment.

Clean reusable face protection with soap and water between patients; if visibly soiled, clean and disinfect.

Recommendations for Gloving

Remove gloves that are torn, cut or punctured

Do not wash, disinfect or sterilize gloves for reuse

If the integrity of a glove is compromised by tears, cuts, or punctures, it should be changed as soon as possible.

Surgical or examination gloves should not be washed before use, nor should they be washed, disinfected, or sterilized for reuse. Washing of gloves can cause a condition known as “wicking,” or penetration of liquids through undetected holes in the gloves. These circumstances may increase the risk of wound contamination and exposure of the DHCP’s hands to microorganisms from patients. Disinfecting agents, oils, certain oil-based lotions, and heat treatments such as autoclaving may result in deterioration of gloves.

Photo credit: Lt. Col. Jennifer Harte, U.S.A.F. Dental Investigation Service, Great Lakes, IL.

Latex Hypersensitivity and Contact Dermatitis

Occupationally-related contact dermatitis can develop from frequent and repeated use of hand hygiene products, exposure to chemicals, and glove use.

Latex Allergy

Type I hypersensitivity to natural rubber latex proteins

Reactions may include nose, eye, and skin reactions

More serious reactions may include respiratory distress–rarely shock or death

Latex allergy is a Type I or an immediate hypersensitivity reaction to the proteins found in natural rubber latex. These proteins can attach to the powder in gloves which, in turn, causes more latex protein to reach the skin.

•This reaction is generally a more severe and immediate systemic reaction than contact dermatitis. Common reactions include runny nose, itchy eyes, hives, and burning skin sensations.

•More severe reactions are characterized by breathing difficulty and, rarely, anaphylaxis (shock) or death.

Photo credit: Arto Lahti, MD, Department of Dermatology, University of Oulu, Finland.

Contact Dermatitis

Irritant contact dermatitisNot an allergyDry, itchy, irritated areas

Allergic contact dermatitis Type IV delayed hypersensitivityMay result from allergy to chemicals used in glove manufacturing

Not all skin reactions are due to an allergic reaction to latex rubber. Most skin reactions are attributed to an irritant or allergic contact dermatitis.

• Irritant contact dermatitis develops as dry, itchy, irritated areas on the skin around the contact area. It is commonly associated with frequent handwashing and is not an allergic reaction.

•The second type of contact dermatitis is a type IV or delayed hypersensitivity or allergic reaction due to contact with a chemical allergen (e.g., accelerators and other chemicals used in the manufacture of patient-care gloves). Reactions are generally localized to the contact area and occur slowly, over a period of 12–48 hours.

General RecommendationsContact Dermatitis and Latex Allergy

Educate DHCP about reactions associated with frequent hand hygiene and glove use

Get a medical diagnosis

Screen patients for latex allergy

Ensure a latex-safe environment

Have latex-free kits available (dental and emergency)

Other recommendations can minimize the risk of contact dermatitis and latex hypersensitivity:

•Educate DHCP workers about reactions associated with frequent hand hygiene and glove use.

•Staff that have dermatologic problems should get a diagnosis from a qualified medical provider before making changes in gloves or hand hygiene agents.

•Screen patients and DHCP for latex allergy in your medical histories.

•DHCP and dental patients with latex allergy should not have direct contact with latex-containing materials and should be in a latex-safe environment with all latex-containing products removed from their vicinity.

•Have both dental and medical emergency latex-free products available at all times.

Environmental Infection Control

Environmental surfaces

May become contaminated

Not directly involved in infectious disease transmission

Do not require as stringent decontamination procedures

Clinical contact surfaces High potential for direct contamination

from spray or spatter or by contact with DHCP’s gloved hand

Housekeeping surfaces Do not come into contact with patients or

devices Limited risk of disease transmission

Categories of Environmental Surfaces

Clinical Contact Surfaces

Housekeeping Surfaces

General Cleaning Recommendations

Use barrier precautions (e.g., heavy-duty utility gloves, masks, protective eyewear) when cleaning and disinfecting environmental surfaces

Physical removal of microorganisms by cleaning is as important as the disinfection process

Follow manufacturer’s instructions for proper use of EPA-registered hospital disinfectants

Do not use sterilant/high-level disinfectants on environmental surfaces

Cleaning Clinical Contact Surfaces

Risk of transmitting infections greater than for housekeeping surfaces

Surface barriers can be used and changed between patients

OR

Clean then disinfect using an EPA-registered low- (HIV/HBV claim) to intermediate-level (tuberculocidal claim) hospital disinfectant

Because clinical contact surfaces come into direct contact with contaminated gloves, instruments, spray or spatter, their risk of transmitting infection is greater than for housekeeping surfaces. These surfaces can subsequently contaminate other instruments, devices, hands, or gloves.

Surface barriers can be used to protect clinical contact surfaces and changed between patients. Surface barriers are particularly useful for surfaces that are hard to clean, such as switches on dental chairs. This practice will also reduce exposure to harmful chemical disinfectants.

If surface barriers cannot be used, clean and then disinfect the surface with an EPA-registered hospital disinfectant effective against HIV and HBV (low-level disinfectant). If the surface is visibly contaminated with blood or other patient material, clean and then disinfect the surface with an EPA-registered hospital disinfectant with a tuberculocidal claim (intermediate-level disinfectant).

Cleaning Housekeeping Surfaces

Routinely clean with soap and water or an EPA-registered detergent/hospital disinfectant routinely

Clean mops and cloths and allow to dry thoroughly before re-using

Prepare fresh cleaning and disinfecting solutions daily and per manufacturer recommendations

Clinical surface disinfection

Least contaminated Most contaminated

Dental Unit Waterlines, Biofilm, and Water Quality

Dental Unit Waterlines, Biofilm, and Water Quality

Microbial biofilms form in small bore tubing of dental units

Biofilms serve as a microbial reservoir

Water should meet the drinking water standards (<500 CFU/ml bacteria)

Untreated dental units cannot reliably produce water that meets drinking water standards .

Legionella is ubiquitous in dental water supply units

Strategies to minimize water-line contamination

1. Flushing water lines for several minutes at the beginning of the day and 30 seconds between patients.

2. Using an independent water reservoir system separate from the municipal water source (sterile water)

3. Using water purification systems: carbon filtration, reverse osmosis and distillation

4. Flush suction aspirator (having removed tip) with non-foaming disinfectant solution.

5. Anti-retraction valves prevents aspiration of patient material back into the handpiece and water lines

Backflow to low-volume suction lines

Do not advise patients to close their lips tightly around the tip of the saliva ejector to evacuate oral fluids.

Never position the suction tubing above the patient. Always have it hang below the patient's head.

Suction lines should be disinfected between patients.

Prevent backflow or anti-retraction valves

Disposable, single-use saliva ejectors

Do not use low volume and high volume suction simultaneously.

Sterilization and Disinfection of Patient Care Items

Sterilization

A sterilization procedure is one that kills all microorganisms, including high numbers of bacterial endospores.

Any item, device, or solution is considered to be sterile when it is completely free of all living microorganisms and viruses.

Sterilization can be accomplished by heat, ethylene oxide gas, hydrogen peroxide gas, plasma, ozone, and radiation

Type of sterilant Measurements/ Calibrations/ Conditions

Pros & Cons

Autoclave (steam under pressure)

121º C or 132 C for 15+ min

Pros: most commonly used, good penetration due to latent heat released by saturated steam after it hits a cool surface.Cons: not suitable for heat sensitive, toxic or volatile chemicals.

Dry Heat 1 hr at 171º C,2h at 160º C16h at 121º C

Pros: safe for metal instruments (do not dull/corrode edges).

Cons: not reliable as autoclave.Low penetrating power.Many materials do not tolerate dry heat.Cannot sterilize liquidsNeeds higher temperature

Type of sterilant Measurements/ Calibrations/ Conditions

Pros & Cons

Chemical sterilization

Gas :Ethylene oxide gas

Liquid Glutaric aldehydee.g. Cidex (2%)

Gas in 30-60ºc for 10h

Immerse in liquid for few hours

Pros: Gas For endoscopes and anaesthetic apparatus

Liquid sterilize plastic and rubber e.g. impressions

Cons: Generally are cancerous and flammable

RadiationUV or IR Prepacked items as

syringesClean, dry, full exposure from all directions

Disinfection

Disinfection is generally a less lethal process than sterilization.

It eliminates nearly all recognized pathogenic microorganisms but not necessarily all microbial forms (e.g., bacterial spores) on inanimate objects.

Disinfectants

The effectiveness of a disinfection procedure is controlled significantly by a number of factors:

the nature and number of contaminating microorganisms

the amount of organic matter present (e.g., soil and blood);

the type and condition of instruments, devices, and materials to be disinfected;

the duration & temperature.

Categories of Disinfectants

High-level

Intermediate-level

Low-level

5.25%–6.15% sodium hypochlorite bactericidal, fungicidal, sporicidal, tuberculocidal, and

virucida A 1:10–1:100 dilution of 5.25%–6.15% sodium hypochlorite

(i.e., household bleach) Decontaminate blood spills on floors

High-level disinfectants Used for items involved in invasive procedures but NOT

withstand sterilization, e.g. Surgical instruments

Vegetative MO Viruses +- bacterial spores (if contact time 6-10 hours)

Contact time 10-30 mins

Use on medical devices, but not on environmental surfaces such as laboratory benches or floors

Used for cleaning surface or instruments without bacterial spores

vegetative microorganisms, all fungi, and inactivates most viruses, tuberculocidal

often correspond to Environmental Protection Agency (EPA)-approved “hospital disinfectants”

Lab benches and housekeeping surfaces

Alcohol, chlorine products, phenols.

Intermediate-level disinfectants

Alcohol: it denatures proteins, is flammable and have low exposure time

Cidal to Vegetative bacteria, enveloped viruses, TB, fungicidal

Hypochlorite: 5.25%-6.15%

Low-level disinfection

most vegetative bacteria except M. tuberculosis, some fungi, and inactivates some viruses

Hospital disinfectants

Used to treat noncritical instruments and devices, not penetrating into mucosa surfaces or sterile tissues

Critical instruments

Penetrate mucous membranes or contact bone, the bloodstream.

Heat sterilize between uses or use sterile single-use, disposable devices

There are three categories of patient-care items depending on their intended use and the potential risk of disease transmission.

Critical items penetrate soft tissue or contact bone, the bloodstream, or other normally sterile tissues of the mouth. They have the highest risk of transmitting infection and should be heat-sterilized between patient uses. Alternatively, use sterile, single-use disposable devices.

•Examples include surgical instruments, periodontal scalers, scalpel blades, and surgical dental burs.

Semi-critical

Contact mucous membranes but do not penetrate soft tissue

Heat sterilize or high-level disinfect

Semi-critical items contact only mucous membranes and do not penetrate soft tissues. As such, they have a lower risk of transmission.

Because most items in this category are heat-tolerant, they should be heat sterilized between patient uses. For heat-sensitive instruments, high-level disinfection is appropriate.

Examples of semi-critical instruments include dental mouth mirrors, amalgam condensers, and impression trays. Dental handpieces are a special case. Even though they do not penetrate soft tissue, it is difficult for chemical germicides to reach the internal parts of handpieces. For this reason, they should be heat sterilized using a steam autoclave or chemical vapor sterilizer.

Noncritical Instruments and Devices

Contact intact skin

Clean and disinfect using a low to intermediate level disinfectant

Noncritical instruments and devices only contact intact (unbroken) skin, which serves as an effective barrier to microorganisms.

These items carry such a low risk of transmitting infections that they usually require only cleaning and low-level disinfection. If using a low-level disinfectant, according to OSHA, it must have a label claim for killing HIV and HBV. However, if an item is visibly bloody, it should be cleaned and disinfected using an intermediate-level disinfectant before use on another patient.

• Examples of instruments in this category include X-ray head/cones, facebows, pulse oximeter, and blood pressure cuff.

Use of chemical agents on skin or living tissues to inhibit

or eliminate microbes Antiseptic agents are selected for their safety & efficacy

Chemical methods Alcohol: protein denaturant. 70% aqueous solution of ethyl

alcohol and isopropyl alcohol are commonly used as skin disinfectants.

Phenolics: Phenol and phenolic compounds (e.g. lysol) lyse the cell membrane and denature proteins at 1-2% (aqueous solution).

Oxidizing agents: inactivate cells by oxidizing free sulfhydryl group, e.g., peracetic acid, iodine, iodophore, H2O2 (3-6%), hypochlorite, and chlorine etc.

Plasma gas sterilization: H2O2 vapors treated with microwave or radio energy to produce reactive free radicals; no toxic byproducts. An efficient sterilization for dry surfaces.

Chemical agents

Alkylating agents

Formalin (37% aqueous solution of formaldehyde), glutaraldehyde

Ethylene oxide gas (made nonexplosive by mixing with CO2 or a fluorocarbon): a reliable disinfectant for dry surfaces.

Detergents: surface-active agents that disrupt the cell membranes.

Anionic detergents: e.g. soaps, and bile salts.

Cationic detergents: e.g., the quaternary ammonium compounds, are highly bactericidal for both the gram-positive and negative bacteria in the absence of contaminating organic matter.

Steps for sterilizing dental instruments

Steps for sterilizing dental instruments

Instruments processing area

Use a designated processing area to control quality and ensure safety

Divide processing area into work areas

Receiving, cleaning, and decontamination Preparation and packaging Sterilization Storage

Most instrument cleaning, disinfecting, and sterilization should occur in a designated central processing area to control both quality and personnel safety.

To prevent cross-contamination, the instrument processing area should be physically or spatially divided into regions for cleaning, packaging, sterilization, and storage.

• In the cleaning area, reusable contaminated instruments are received, sorted, and cleaned.

•The packaging area is for inspecting, assembling, and packaging clean instruments in preparation for final sterilization.

•The sterilization and storage area contains the sterilizers and related supplies, incubators for analyzing spore tests (if performed in office—although some states require using a testing service), and can contain enclosed storage for sterile items and disposable (single-use) items.

Receiving

Cleaning

Automated Cleaning

Manual Cleaning

Automated Cleaning

Ultrasonic cleaner Instrument washerWasher-disinfector

Cleaning is the basic first step in all decontamination processes. Cleaning involves the physical removal of debris and reduces the number of microorganisms on an instrument or device. If visible debris or organic matter is not removed, it can interfere with the disinfection or sterilization process.

Automated or mechanical cleaning equipment, such as ultrasonic cleaners, instrument washers, and washer-disinfectors, are commonly used to clean dental instruments. Automated cleaners increase the efficiency of the cleaning process and reduce the handling of sharp instruments. After cleaning, instruments should be rinsed with water to remove chemical or detergent residue.

Photo credit: Chris Miller, PhD, Indiana University School of Dentistry.

Manual Cleaning

Soak until ready to clean

Wear heavy-duty utility gloves, mask, eyewear, and protective clothing

If manual cleaning is necessary, soak instruments in a rigid container filled with detergent, disinfectant/detergent, or an enzymatic cleaner. This step prevents drying of patient material and makes cleaning easier and less time consuming.

•Do not use high-level disinfectants/sterilants (e.g., glutaraldehyde) as instrument-holding solutions.

•To avoid injury from sharp instruments, personnel should wear puncture-resistant, heavy-duty, utility gloves (i.e., not patient care gloves) when handling or manually cleaning contaminated instruments and devices. To protect against splashes, a facemask, eye protection or face shield, and a gown or jacket should be worn.

Photo credit: Lt. Col. Jennifer Harte, U.S.A.F. Dental Investigation Service, Great Lakes, IL.

Preparation and Packaging Critical and semi-critical items that will be stored should be

wrapped or placed in containers before heat sterilization

Hinged instruments opened and unlocked

Place a chemical indicator inside the pack

Wear heavy-duty, puncture-resistant utility gloves

Packaging and sealing:

After thorough cleaning and drying of instruments, critical and semi-critical instruments that will be stored before use should be wrapped or placed into container systems prior to heat sterilization. This step protects items from contamination after the sterilization cycle and during storage.

Open or unlock hinged instruments so that all surfaces are exposed.

Place a chemical indicator inside each wrapped package. If the indicator cannot be seen from the outside, place another indicator (e.g., indicator tape) on the outside of the package.

Always wear heavy-duty, puncture-resistant utility gloves while inspecting and packaging instruments.

Sterilization Monitoring Types of Indicators

Mechanical Measure time, temperature,

pressure

Chemical Change in color when physical

parameter is reached

Biological (spore tests)Use biological spores to assess

the sterilization process directly

Proper monitoring of sterilization procedures should include a combination of process indicators, including the following:

•Mechanical—involves assessment of cycle time, temperature, and pressure by observing the gauges or displays on the sterilizer.

•Chemical—uses sensitive chemicals that change color when a given parameter is reached (e.g., heat-sensitive external tape, internal chemical indicator strip).

•Biological—this method is the most valid method for monitoring the sterilization process because it assesses the process directly. It does so by using the most heat-resistant microorganisms and not by using indicators that only test the physical and chemical conditions necessary for sterilization.

Mechanical and chemical indicators should be assessed with each load. If either mechanical indicators or internal or external chemical indicators indicate inadequate processing, items in the load should not be used until reprocessed.

Biological indicators should be assessed at least once a week.

Storage of Sterile and Clean Items and Supplies

Use date- or event-related shelf-life practices

Examine wrapped items carefully prior to use

When packaging of sterile items is damaged, re-clean, re-wrap, and re-sterilize

Store clean items in dry, closed, or covered containment

DHCP have a choice about how they maintain their instrument storage area — either date- or event-related shelf-life practices. In date-related packing, every sterilized package is expiration-dated and the instruments are used on a “first in, first out” basis. In event-related practice, the contents of a sterilized package should remain sterile indefinitely unless some event, for example, torn or wet packaging material, causes it to become potentially contaminated. It is still useful to place the date of sterilization and identify the sterilizer used if multiple sterilizers are utilized in the office. In case of sterilization failure, this information would facilitate retrieval of processed items.

•Examine each package. If it is damaged in any way, items should be re-cleaned, re-wrapped, and re-sterilized. Even if an event-related approach is used, all packages should be labeled with the date of sterilization and which sterilizer was used, should a sterilization failure occur.

•Store all sterile and clean items and supplies in dry, closed, or covered cabinets.

Medical Waste

Medical Waste: Not considered infectious, thus can be discarded in regular trash

Regulated Medical Waste: Poses a potential risk of infection during handling and disposal

There is no evidence that traditional medical waste management has contributed to increased levels of disease in the community or among health care personnel.

The majority of waste generated in a medical or dental office (~98%–99%) is not considered infectious and can be discarded in the regular trash. Examples include used gloves, masks, and lightly bloodied gauze.

Some waste, such as used needles, extracted teeth, and gauze soaked in blood, may pose a potential risk of infection, however, and warrants special precautions during handling and disposal. Follow federal, state, and local regulations for proper treatment and disposal.

Regulated Medical Waste Management

Properly labeled containment to prevent injuries and leakage

Medical wastes are “treated” in accordance with state and local EPA regulations

Processes for regulated waste include autoclaving and incineration

Regulated medical waste requires careful containment for treatment or disposal. A single leak-resistant biohazard bag is usually adequate to contain non-sharp, regulated medical waste. Puncture-resistant containers with a biohazard label, such as sharps containers, are used as containment for scalpel blades, needles, syringes, and unused sterile sharps.

Medical waste, both nonregulated and regulated, should be stored and disposed of in accordance with federal, state, and local EPA regulations.

Treatment of regulated waste can involve on-site or off-site autoclaving and incineration. Never include extracted teeth with amalgam in regulated waste when disposed by one of these methods.

Photo credit: NIOSH Web site.

THANK YOU

Acknowledgement:

Dr. Abdelraheem Yaseen

Dr. Rawan Hamati