Dr Maria K Siddiqui

DR MARIA K SIDDIQUI

Infection Control  Aim: To provide highest level of infection control possible

and practical that will ensure a safe environment for both patient and clinician.  Objectives:  Elimination of cross contamination by breaking the chain of infection.  Reduction of available pathogenic microorganism to a level at which normal resistance mechanisms of the body may prevent infection.

 Application of universal precautions by treating each

patient as if all human blood and body fluids are known to be infectious for HIV,HBV and other blood born pathogens.

Guideline for Infection Control  ADA and Center for disease control and prevention have

 





developed guidelines for infection control. All guidelines are based on concept of standard precautions, previously called universal precautions. A parallel approach presented in 1987 called body substance isolation which focuses on reducing transmission of infection from any most body substance of the patent to the health care work. The universal precautions emphasize on barrier procedures, routine autoclaving of instruments and means of handling potentially infectious material. In 2003 CDC guidelines combined body substance isolation and universal precautions called Standard infection control procedures.

OSHA and Dental Practice  In USA OSHA(occupational safety and health

administration) is responsible for establishing standard for safe and healthy working in almost all industries  Blood-born pathogen standard came into effect in 1992.  BP standard covers instrument sterilization and storage handling of contaminated equipment, disposal of medical waste. HBV vaccination to staff reporting needle stick injuries, level of washing and storing laundry.  The BP standard is a formidable document.

Barriers for Patient and Clinician Protection  Immunization  Management programs:

a) Recommended tests Serologic test for herpes simplex virus I (HSV I) antibodies to determine susceptibility to primary HSV. Annual tuberculin test b) Written records: keep written records of immunization, reimmunization and booster plan for regular follow up.

 Clinical Attire:  The wearing apparel of clinicians and their assistants is

 

  

vulnerable to contamination from splash, aerosol and patient contact. Gown, scrub suit with solid closed fronts with out pockets. Hair or head cover Face mask Face shields Proper syringe capping Techniques

HIV / AIDS  Acquired immunodeficiency syndrome is the end point of HIV

    

infection. Aids virus is a retrovirus. Aids is the final progressive process of immunological deficit mediated by the virus. Pnuemocystis carinii pnuemonia is the most common opportunistic infection. In severe HIV infection the CD 4+ T- cell count of 200/uL or less. Modes of Transmission: Sexual transmission Infected mother to infant Transfusion of infected blood Intravenous drug use

Investigations in adults  Detection of HIV antibody: enzyme-linked       

immunosorbent assay (ELISA), Western blot. Assessment of viral load: detection of virus or viral antigen: HIV RNA or branched DNA (bDNA) assay. FBC: anaemia, thrombocytopenia, lymphocytopenia with reduced CD4 cell count. Raised ESR. Assessment of other infections: eg tuberculosis, hepatitis B, cytomegalovirus (CMV), toxoplasma, syphilis, varicella. Screening for co-existing sexually transmitted diseases (STDs). Baseline CXR and cervical smear. It may be appropriate to screen for glucose-6-phosphate dehydrogenase (G6PD) deficiency in appropriate racial groups.

Diagnosis  Is based on detecting anti-HIV antibodies in serum.  Acute infection may be detected by the presence of P24

antigen or HIV RNA by polymerase chain reaction (PCR) and precedes the appearance of IgM and IgG.  A combination test checking for the presence of HIV antibody and p24 antigen (the so-called 'fourth generation test') is provided by hospital and is very accurate. It takes about four weeks to get the result back.

Investigation in children  Standard anti-HIV IgG antibody tests cannot be used

before 18 months of age, as maternal antibodies may be detected.  PCR and virus culture are the best investigations in children born to infected mothers.  38% of infected infants can be detected within the first 48 hours after birth, rising to 96% at four weeks .

Oral manifestations of HIV  Principal signs of HIV  Oral candidiasis  Hairy leukoplakia

 Kaposi sarcoma  Chronic Herpes Simplex

Oral Candidiasis  Fungal infection.  Usually present as a white plaque on the palate.  Plaque can be sore and very common among HIV

infected individuals.

Candidiasis

Oral Hairy Leukoplakia  Lesion commonly appear on lateral surface of tongue.  Wide variation in size, severity and characteristics of

lesion.  Condition is highly predictive of future development of aids.  It is caused by Epstein-Barr virus (EBV)

Kaposi Sarcoma  Diagnostic for aids.  Found in 28%-34% of aids patients.  Palate is the most common intraoral site.  Most common finding in case of pediatric aids.  Oral candidiasis

 Parotid gland enlargement  Herpetic infection

Kaposi Sarcoma

Oral Hairy Leukoplakia

Oral Hairy Leukoplakia

Hepatitis B and C  Hepatitis is more prevalent than HIV.  In poor countries 8%-10% of the total population

is chronically infected.  In poor countries liver cancer is a result of chronic HBV infection and among top 3 causes of death in men.  1% population is chronically infected in high income countries.  HBV is primarily the disease of adults in united states. New infections are common in the age 2029.  On the other hand in poor countries HBV is more common in children.

Transmission of HBV and HCV  HBV and HCV are transmitted by contact with

infected blood.  Primary transmission routes: Sexual contact both homosexual and heterosexual and unprotected sex. Sharing of infected needles/ Needle stick injury Perinatal transmission to an infant born to an infected mother.

Needle Stick Injury

Single Hand Needle Capping Technique

 Fatality rate from HBV is low (0.5%-1%) infected

person recover completely in due course.  HBV carriers are at risk of long term sequelae such as chronic liver disease, liver cirrhosis and liver cancer.  Infected young children (30%-90%) can develop chronic infection. In case of infected adults 2%-10% can develop chronic infections.  Chronic infection can be asymptomatic but 15%-25% of this group can die prematurely from cirrhosis or liver cancer.

 Signs and symptoms of hepatitis B and C are:  Fatigue  Abdominal pain

 Loss of appetite  Intermittent nausea  Vomiting  Jaundice  Health care workers are at higher risk of than general

population because they are likely contact with carriers.

 Blood and serous fluids have highest conc of HBV in 

  

infected person; concentration in saliva in little lower. Carriers of HBV can easily transmit the diseases to any one to whom they come in contact in day to day life. HBV virus can also be transmitted by percutaneous and non percutanoeous routes. Risk of contracting HBV is 3-10 times greater for dentist than for general population. Types of hepatitis identified are A,B,C,D and E.

 HCV infection has an insidious onset and can easily be 

  

missed at early stages like HBV. Majority of HCV infected person show no symptoms however some patients do show symptoms similar to HBV. No vaccine has yet been develop for HCV. The barrier precautions and sterilization procedures for preventing HCV are same as HBV. For HBV immunization through a series of 3 injection over 6 months will be required.

 Vaccination specific for HBV does not protect against

HCV.  Hepatitis C Testing  Also known as: Hepatitis C Antibody; Anti-HCV; HCV-PCR; HCV-RNA; Hepatitis C Viral Load  Formal name: Viral Hepatitis C Antibody Screen; Viral Hepatitis C RNA by PCR; Hepatitis C Virus Genotype

Table 1. Serological tests that constitute the diagnostic panel for HBV

HBsAg

Hepatitis B surface antigen

Active infection (acute or chronic)

Anti-HBs

Hepatitis B surface antibody

Immunity (vaccination or infection)

Anti-HBc

Hepatitis B core antibody

Infection (past or current)

HIV issues in Dental Practice and Dental education  The rights of infected Dentist to practice.  On the other hand,  Willingness to treat HIV infected patient is an issue , which

should deal with vigorously.  According to ADA code of ethics refusal to treat HIV patient is unethical.  However it is also illegal, 1.The risk of cross infection despite standard precaution, 2. Many Dentist already have treated HIV infected without knowing it.  Same issue in Dental education 1. HIV+ student admitted to Dental school or not 2. What if becomes HIV+ during course.

Dental Unit Water lines  An issue related to water line infection is back flow.  Cross connection(contaminated materials entering

public water supply) is possible through the high speed hand piece, air and water syringe, however risk is extremely low.  Back flow relates to the chance of HIV, HCV, HBV infections but possibility is close to zero  The use of self contained water systems in the dental office not connected to public water supply is a recommended measure to reduce any possible risk

Instruments      

   

Critical instruments: Instruments used to penetrated soft tissue or bone. Such as forceps, blade, scalpel, chisel, Scalers. Should be sterilized after each use. Semi critical instruments: Instruments that do not penetrate soft tissue or bone but contact oral tissues. Such as mouth mirror, condenser etc. Should be sterilized after each use or high level disinfection. Non critical instruments: Instruments or devices such as external components of ray heads that come in contact with intact skin. These instruments have low risk of transmitting infection.

Definitions  Cleaning  process which physically removes contamination but

does not necessarily destroy micro-organisms  prerequisite before decontamination by disinfection or sterilisation of instruments  organic material prevents contact with microbes, inactivates disinfectants  Disinfection  using an agent that destroys germs or other harmful microbes or inactivates them, usually referred to chemicals that kill the growing forms (vegetative forms) but not the resistant spores of bacteria

 Antisepsis  destruction of pathogenic microorganisms existing in their vegetative state on living tissue  Sterilization  any process, physical or chemical, that will destroy all forms of life, including bacterial, fungi, spores, and viruses

Sterilization  Process by which an article surface or medium is freed to   



all microorganism either in vegetative or spore form. Moist Heat: steam under pressure Dry heat Chemical vapor Ethylene Oxide

 Choice of sterilization method depends on practical issues

such as ease of use or material compatibility  Cleaning of objects needed before attempt at sterilization

Autoclave (Steam under pressure)  Destruction of microorganism by heat takes place as a

 

  

result of inactivation of cellular proteins or enzymes. Moist heat causes coagulation of proteins. Temp: 121 C at 15 pounds pressure for 15 mins. Use 30 min for heavy load of to ensure penetration. Advantage: All microorganisms, spores, and viruses are destroyed quickly and efficiently. Economical

 Disadvantage:  Corrosion of carbon steel instruments  Materials to be sterilized should be wrapped in paper

and steam permeable plastic.

Dry Heat  Action of dry heat is oxidation.

 Temp 160 C (320 F).  Time: 2 hours or 1 hour for 170 C  Advantage:  No corrosion  Well suited for sharp instruments.

 Use full for material that cannot stand stem under

pressure.  Disadvantage:  High temperature is critical for plastic materials.

Autoclave

Chemical Vapor Sterilization  A combination of alcohols, formaldehyde, ketone,

water and acetone heated under pressure produces a gas that is effective as strigling agents.  Time / Temp: 20 min 127 o C -132 o C  Pressure: 20-40 pounds

 Advantage:  Rust free operation for carbon steel instruments.  Less time consuming

Sterilization for Heat sensitive Instruments  Cold sterilization (Liquid chemicals The use of chemicals classified as "sterilants)  10 hour of exposure to chemical liquid agent.  This sterilization is followed by aseptic rinsing with sterile water, drying and if the instrument is not used immediately, place in a sterile container.

Physical Methods  Filtration  Used on fluids and on air supplies  Gamma-Irradiation  Used on disposable plastics, e.g. in sealed packs  Only in specialised centres

Mercury Safety  Dental amalgam contains elemental mercury. It

releases low levels of mercury vapor that can be inhaled. High levels of mercury vapor exposure are associated with adverse effects in the brain and the kidneys.  Based on this evidence, FDA considers dental amalgam fillings safe for adults and children ages 6 and above.

 Research has not shown any health effects from

amalgam fillings in pregnant women. However, mercury can cross the placenta. Women should not get amalgam fillings during pregnancy. Dentists can suggest other materials for any pregnant woman who needs a cavity filled.  Occupational exposure is completely preventable with the implementation of proper mercury hygiene practices.  There is no evidence in the scientific literature that the minute amounts of mercury vapor that may be released from amalgam restorations pose a health threat. Allergic reactions to mercury and other constituents of amalgam have been documented, but are exceedingly rare.

 Some individuals have an allergy or sensitivity to

mercury or the other components of dental amalgam (such as silver, copper, or tin). Dental amalgam might cause these individuals to develop oral lesions or other contact reactions.

Alternative to Amalgam  Composite resin filling  Glass ionomer filling  Gold fillings

Mercury Hygiene Guidelines  The ADA classifies amalgam scrap in the following manner:  Non-contact amalgam (scrap) is excess mix leftover at the end of a dental procedure. Many recyclers will buy this clean scrap.  Contact amalgam is amalgam that has been in contact with the patient. Examples are extracted teeth with amalgam restorations, carving scrap collected at chair side, and amalgam captured by chair side traps, filters, or screens.

 Chair side traps capture amalgam waste during









amalgam placement or removal procedures (traps from dental units dedicated strictly to hygiene may be placed in the regular garbage). Vacuum pump filters or traps contain amalgam sludge and water. Some recyclers will accept whole filters, while others will require special handling of this material. Amalgam sludge is the mixture of liquid and solid material collected within vacuum pump filters or other amalgam capture devices. Empty amalgam capsules are the individually dosed containers left over after mixing pre capsulated dental amalgam. The use of disposable pre capsulated alloys eliminates many potential sources of mercury vapor and minimizes the possibility of accidental spillage.

 The following items should be considered when

establishing an effective mercury control program:  Use only precapsulated alloy. If, for some reason, elemental mercury must be stored, store it in unbreakable, tightly sealed containers on stable surfaces.  Perform all operations involving mercury over an area that has an impervious and suitable lipped surface so as to confine and facilitate recovery of spilled mercury or amalgam. Whenever possible, perform these operations over a tray.

 Clean up any spilled mercury immediately.  Use a no-touch technique for handling amalgam. If

contact is made with mercury, the area affected should be washed with soap and water to reduce the time that the microscopic particles cling to the skin.  Use tightly closed disposable capsules during amalgamation. Loss of mercury during trituration can be detected by wrapping adhesive tape around test capsules prior to the mechanical mixing. If the capsules are tight and no mercury is thrown out, the adhesive tape will be clean after trituration.

 Place non-contact, scrap amalgam in wide-mouthed,

airtight container that is marked “Non-contact Amalgam Waste for Recycling.” Make sure the container lid is well sealed.  Stock amalgam capsules in a variety of sizes. After mixing amalgam, place the empty capsules in a widemouthed, airtight container that is marked “Amalgam Capsule Waste for Recycling.” Capsules that cannot be emptied should likewise be placed in a wide-mouthed, airtight container that is marked “Amalgam Capsule Waste for Recycling.” Make sure the container lid is well sealed. When the container is full, send it to a recycler.

 Salvage contact amalgam pieces from restorations after

removal. Store and label contact amalgam waste separately from non-contact waste. Recycle the contact amalgam waste according to instructions provided by your recycler.  Recycle amalgam scraps through refiners who are properly licensed by the Environmental Protection Agency. The ADA’s Directory of Dental Waste Recyclers can be found at: http://www.ada.org/prof/resources/topics/topics_amalre cyclers.pdf

 Work in well-ventilated spaces that have rapid fresh air

exchanges. If air conditioning is present, replace filters often.  Avoid carpeting dental operatories, as decontamination is not possible. The use of a continuous, seamless sheet of flooring that extends up the walls at least 10 centimeters is recommended. If the operatory is already carpeted, do all mercury transfers in another area. Carpeting and floor cracks serve as collectors for spilled mercury.

 Eliminate the use of mercury-containing solutions.  Avoid heating mercury or amalgam. Keep it away from

direct sunlight and other heat sources.  Water spray and high-volume evacuation should be used when removing old amalgam restorations or finishing new ones. A fiber-type mask should also be worn when cutting out old amalgams. Evacuation systems should have traps or filters, which should be checked and cleaned or replaced periodically.

 Use conventional dental amalgam compacting



   

procedures, manual and mechanical, but avoid the use of ultrasonic amalgam condensers. Expressing excess mercury from amalgam must be avoided. Disposable pre-capsulated alloys should be used. Amalgamator arms and capsules should be covered during trituration. Contaminated instruments should be thoroughly cleaned before sterilization. Disposable items contaminated with mercury should be discarded in properly sealed containers. Have periodic mercury vapor level determinations made in operatories.

 Office Monitoring  Periodic monitoring can be a valuable adjunct for

assessing the effectiveness of mercury hygiene procedures in the dental office. The dental office should be monitored for mercury vapor once every two years, or more frequently if contamination is suspected.  In the event of serious contamination, such as a spill, the office should be monitored until a safe threshold is reached. Arrangements for monitoring can usually be accomplished by contacting the local Office of Environmental Health.

 Medical Surveillance  Biologic monitoring through periodic urine analysis

for mercury is a recommended method for assessing the exposure of dental office personnel. These periodic checkups are excellent as an indirect evaluation of the effectiveness of mercury hygiene in an office.  The maximum allowable mercury level is 0.15 milligrams/liter (150 micrograms/liter) according to OSHA, and the normal level generally is approximately 0.015 milligrams/liter (15 micrograms/liter).

 Cleanup of Spilled Mercury  Any spilled mercury should be cleaned up immediately.

Effective techniques for cleanup of any spilled mercury include using a wash-bottle trap connected to a lowvolume aspirator of the dental unit for removing visible droplets of mercury. The trap bottle connection should keep the mercury in the bottle and not let it be sucked into the dental unit. Other devices for recovering mercury include handheld pumps, aspirator bulbs, or plastic syringes. Sponges are generally not effective for mercury cleanup. Adhesive tape, tin foil, or a fresh mix of dental amalgam can remove droplets of mercury if undisturbed. Reagents that combine with mercury may facilitate cleanup. Commercially available spill cleanup kits that contain a combination of these devices and materials have proved useful. A household vacuum cleaner should not be used on spilled mercury or on contaminated floors.