INFECTION CONTROL AND OFFICE SAFETY
INTRODUCTION:
Pervasive increase in serious transmissible disease over the last few
de...
3) Susceptible host
4) Portal of entry
VIRULENCE:
Virulence of an organism refers to the degree of pathogenecity or
streng...
conditions (Such as fever) cause the virus to leave the nerve cell and attack
the surface again. E.g. Herpes zoster.
Oppor...
A high speed hand piece is capable of creating air borne contaminants
from bacterial residents in dental unit water spray ...
it is frequently contaminated with blood. Although blood is not visible in
saliva but it may be present. All blood borne d...
III. To ensure each patient that the level of general office cleanliness
and sanitation will be maintained within the prof...
A patient may be a carrier of disease. A carrier is one individual who
harbors the specific organisms of a disease in the ...
Professional organizations are a valuable resource for infection
control and other professional information.
1) American d...
The purpose of FDS is to assure the safety and effectiveness of
medical devices by requiring “good manufacturing practices...
• Housekeeping – term that relates to clean
up of treatment soiled respiratory equipment, instruments. Counters and
floors...
walled leak proof containers labeled that are closable from which
needle cannot be easily spilled.
8) Contaminated reusabl...
16)Contaminated sharps are regulated waste, discarded in hard walled
containers. Containers contaminated outside must be p...
• Information about the selection, placement,
use, removal, disinfection, sterilization and disposal of PPE.
• Information...
AIDS is a severe condition caused by infection with the human
immunodeficiency virus (HIV-1).
AIDS was reported as a new c...
c) Recipients of blood transfusions or blood products.
d) Male and female prostitutes who do not practice safe sex.
e) Rec...
Virus that can infect and destroy more lymphocytes leading to depletion in
T4 cells which leads to variety of infections a...
CLASSIFICATION OF HIV INFECTION AND AIDS :
CDC gave the classification for HIV infection in 1993
CD4 count
A
Asymptomatic
...
I. Incubation period :
Ranges from the tissue of infection until the time when symptoms of
AIDS are evident which may by 1...
Constitutional disease : HIV-1 wasting syndrome, long term fever,
sever weight loss, anemia, chronic diarrhoea, chronic we...
Of all American health care workers injured by needles and sharp
instruments used to treat HIV infected persons only 0.3% ...
4) HIV is killed by all methods of sterilization. When used properly, all
disinfectants except some quaternary ammonium co...
In the 8 years after AIDS was recognized 38,000 persons developed
the disease. During the same period an estimated 38,400 ...
2) Non percutaneous : transfer of infections body secretions,
saliva, blood and crevicular fluid.
3) Perinatal exposure
4)...
Because principle means of transmission is by feces, prevention an that
level is indicated.
a) Public health control of fo...
Active immunity : occurs by stimulation of an individuals own immune
response. Protection is provided only after a latent ...
Herpes virus produce disease with latent, recurrent and sometimes
malignant tendencies.
Abbreviation Name of the virus Inf...
3) Infection of sensory and autonomic nerve endings.
4) Virus travel along the nerve to ganglion.
5) After primary disease...
though infected with blood borne disease agents and this has been
incorporated as a rule into the blood borne pathogens st...
3) To assist in managing and caring for infected patient.
4) To reinforce use of adequate infection control procedures bea...
1) Fit hand well, no interference with motion, glove cuff extends to
provide coverage over cuff of long sleeve.
2) Tactile...
Pinholes are present under all types of gloves and latex gloves are no
exception. The danger in pinholes is that microorga...
FACTORS AFFECTING GLOVE INTEGRITY
A) Length of time :
1) New pair for each patient
2) Total time should be no longer than ...
Symptoms Conditions
1) Hands become dry, red itchy
and sometimes cracked
Irritant contact dermatitis
2) Redness, initial i...
• If a protective garment becomes visibly soiled or saturated with
chemicals or body fluids, it should be changed immediat...
Any area that can be covered where contamination is possible during
dental treatment should be covered. Barriers have been...
Use of mask:
1) Adjust the mask and position eye wear before a scrub or hand wash.
2) Use face mask for each patient more ...
• Eye wear should provide front, top and side protection.
• Eye wear is also used to protect eyes from high intensity ligh...
A) Finger nails :
Maintain clean, smoothly trimmed short finger nails with week cared
for cuticle to prevent breaks where ...
1) Use a liquid surgical scrub containing an antimicrobial agent
poridone iodine has a broad spectrum of action chlarhexid...
2) Begin with the thumb, use small circular strokes on each side of
thumb and each finger, then plan and back of hand. Ext...
1) Wear mask and eye wear.
2) Wash hands and arms using surgical liquid antimicrobial soap to
remove gross surface dirt.
3...
3) Use the following to control contamination
a) Clean and sterilize instruments
b) Protect surfaces and equipments that a...
but will not touch bone or
penetrate soft tissue eg
Mouth mirror, amalgam
condensers, handpiece,
impression trays.
or high...
contaminated and side arms as dental chair, contaminated drawer
handles, radiographic view box switch.
9) Use a second tow...
b) Wash with running water, do not scrub. Allow the hand to
bleed freely for 5 months under tap water.
c) If necessary ind...
Infection control needs in dental treatment facilities require the use of
disinfectants in several forms.
1) Surface disin...
2) Concentration of chemical.
3) Length of exposure time.
4) Amount of accumulated debris.
CLASSIFICATION OR DISINFECTANTS...
4) Non toxic
5) Surface compatibility.
Should not carrode instruments and other metallic surfaces.
6) Residual effect on t...
- Isopropyl alcohol have high bactericidal activity at a concentration of
99%.
- Water solution work best.
1) Alcohols wor...
Three types of gluteuraldehyde preparation are there alkaline, acidic
and neutral preparations.
Action :
They are high lev...
Action :
- They are cytoplasmic parsons by penetrating and disrupting all wall
thereby backing to dematuration of intracel...
2) Chlorine compounds
Action : Microorganisms are destroyed primarily by oxidation of
microsomal enzymes and all membrane ...
Chlorhexidene gluconate 20% w/v.
3) Sterillium
Hand disinfectant. Alcohol preparation.
4) Bacillo-x 25 :
- Surface disinfe...
PREPARATION FOR STERILIZATION :
Instruments and equipments intended for sterilization / disinfection
procedure must be car...
1) Ultrasonic cleaning.
2) Manual cleaning.
MANUAL CLEANING :
Ultrasonic processing is a method of choice but when manual
...
5) Penetration into areas of instruments where the bristles of brush may
be unable to contact.
6) Removal of tarnish.
PRIN...
3) Clear packages with self seal permit instrument identification without
special labeling.
III) PREPARATION :
Each method...
2) FILTERATION
A) Candle filths :
a) Chamber land and doulton filter – made of unglazed ceramic
which after use can be cle...
Heat :
Moist heat is mast reliable method of sterilization and should be the
method of choice unless contraindicated. Mate...
2) Incineration :
Excellent method for safely destroying materials such as
contaminated cloth, and pathological materials....
1900
C – 1.5 min
Advantages :
- Carbon steel instruments and burs do not rust.
- When maintained at correct temperature. I...
GLASS BEAD :
- Bead less than 1 mm in diameter. Larger beads are not effective in
transferring heat.
- Large air space bet...
- In case where boiling is considered, adequate material should be
immersed in water and boiled for 10-30 min.
- The steri...
Disadvantages :
- Unsuitable for oils or powders that are impreviors to heal.
- Items sensitive to the elevated temperatur...
2) Liquids : Reduce chamber slowly at an even rate over 10 to 12
minutes to prevent boiling as escape of fluids into the c...
Cooling at the completion of cycle :
Instruments are dry instruments need a short period for cooling.
Care of sterilizer :...
Plastic and rubber products need to be aerated for atleast 24 hours.
Metal instruments are ready for immediate use.
Advant...
- If bacteria are rapidly subjected to temperature below – 350
C, ice
crystals that form within the cell produce a lethal ...
4) Glass slab ++ ++ ++ ++ +
5) Hand instruments
- Carbon steel - ++ ++ ++ +
- Stainless steel ++ ++ ++ ++ -
6) Morrars - +...
1) Alginate – chlorine compounds.
2) Polysulfide rubber base – Glutaraldehyde, iodophar, chlorine
compound.
3) Silicone – ...
from handpieces, syringes etc. may contain elevated concentration of
pseudomonas, mycobacterial, legionella.
ADA recommend...
scalpel blades, orthodontic
wires, endodontic
instruments (reamers and
files)
puncture resistant
containers. Containers
sh...
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Infection control and office safety

  1. 1. INFECTION CONTROL AND OFFICE SAFETY INTRODUCTION: Pervasive increase in serious transmissible disease over the last few decades has created global concern and has made health care personnel to comply with rigid infection control procedures to prevent cross infection. The emphasis of infection control in dentistry that occurred in 1980s has now resulted in impressive approaches to prevention of disease spread in the office. These approaches are directed towards patient protection and protection of all numbers of dental team, so that dentistry has never been safe than it is today for patient and staff alike. Although there is a common goal of infection control i.e. to eliminate or reduce the number of microbes shared between people there are several approaches that may be used to achieve its desired end result. These approaches vary from one office to the next depending on the type of dental procedures performed, the number and training of employees, office design, the pattern of patient flow through the office, and the type of dental equipment used. Most infection, control procedures have been validated for effectiveness when used currently, when they are misused, increased chances for disease spread can occur. This is one of the reasons why infection control procedures frequently have safety factors built in to help ensure success under a variety of unpredictable conditions. Thus one must be careful while using these infection control procedures. OVERVIEW: THE CHAIN OF INFECTION: The life and growth of pathogens (disease causing organisms) is a cycle as a chain. Break the chain and you break the infections process. The chain of infection consists of four parts. 1) Virulence 2) Number of microorganisms
  2. 2. 3) Susceptible host 4) Portal of entry VIRULENCE: Virulence of an organism refers to the degree of pathogenecity or strength of that organism in its ability to produce disease. Number of microorganisms: In addition of being virulent, pathogenic microorganisms must be present in large enough members to overwhelm the body’s defense. The number of pathogens is directly related to the amount of bioburde present, the organic materials such as blood and saliva. Use of dental dam and high volume evacuation helps to minimize bioburden on surfaces and reduce the number of microorganisms in the aerosol. Susceptible host: A susceptible host is a person who is unable to resist infection by the pathogen. Portal or entry: To cause infection microorganisms must have a portal of entry as means of entering the body. The portals of entry for air-born pathogens are through mouth and nose. Blood born pathogens must have access to the blood supply as means of entry into the body. This can occur through a break in the skin caused by needle stick, a cut as even a human bite. TYPES OF INFECTION: Acute Infection: It is of short duration. In acute infection symptoms are often severe and usually open soon after the initial infection occurs. Chronic infection: Chronic infections are those in which microorganisms is present for a long duration. Latent infection: A latent infection is a persistent infection in which the symptoms come and go. The virus enters the body cause the infection. It then lies dormant, away from the surface, in a nerve cell until certain
  3. 3. conditions (Such as fever) cause the virus to leave the nerve cell and attack the surface again. E.g. Herpes zoster. Opportunistic infection: They occur in individuals where resistance is decreased or compromised. E.g. individual recovering from influenza may develop pneumonia. METHODS OF DISEASE TRANSMISSION: 1) DIRECT TRANSMISSION: Pathogens can be transferred by coming into direct contact with infectious lesion as infected body fluids, including blood, saliva, semen and vaginal secretions. Many viruses and pathogenic bacteria are transmitted directly and cause hepatitis, herpes infection, HIV and tuberculosis. 2) INDIRECT TRANSMISSION: The indirect transfer of organisms to a susceptible person can occur by handling contaminated instruments as touching contaminated surfaces and then touching the face, eyes as mouth. It important to wash the hands frequently to avoid indirect transmission of microorganisms. Splash or splatter : Blood, saliva or nasopharyngeal secretions can be sprayed as spattered during many dental procedures. Disease can be transmitted during a dental procedure by splashing the mucosa as non intact skin with blood or blood contaminated saliva. Non intact skin in which there is a cut, scrape or needle stick injury provides an entrance for pathogens into the body. AIR BORNE TRANSMISSION: Also known as droplet infection as a spread of disease through droplets of moisture containing bacteria or viruses. Most of the contagious respiratory diseases are caused by pathogens carried in droplets of moisture. Some of these pathogens are carried long distances through the air and ventilation systems.
  4. 4. A high speed hand piece is capable of creating air borne contaminants from bacterial residents in dental unit water spray system and from microbial contaminants from saliva, tissues, blood, plaque and fine debris cut from carious teeth. With suspect to size, these air born contaminates exist in the form of splatter, mist and aerosol. Aerosol: Invisible particles ranging from 50µm to approximately 5µm that can remain suspended in air and breath from hours. No scientific evidence indicates that fine aerosols have transmitted the blood borne infection caused by hepatitis B virus. Mists: Consist of droplets estimated to approach 50 µm visible in a beam of light. They tend to settle down from air after 5-15 minutes. e.g. Tuberculosis, hepatitis and other viral disease. Spatter: Particles larger than 50µm and even visible splashes. The have distinct trajectory frilling with in 3 feet as patients mouth thus can result in coating of face and outer garments of attending personnel, in potential route of spread. Consists of large droplet particles contaminated with blood, saliva, and other debris. Spatter is created during all restorative and hygiene procedures involving rotary and ultrasonic dental instruments use by air water syringe may also produce spatter. PARENTERAL TRANSMISSION: Through the skin, as with cuts or punctures parenteral transmission of blood born pathogens can occur through needle stick injuries, human bites, cuts, abrasions or break in the skin. BLOOD BORNE TRANSMISSION: Certain pathogens known as blood borne are carried in the blood and body fluids of infected individuals and can be transmitted to others. Blood borne transmission occurs through direct or indirect contact with blood and other body fluids. Saliva is of great concern during dental treatment because
  5. 5. it is frequently contaminated with blood. Although blood is not visible in saliva but it may be present. All blood borne diseases are transmitted by improperly sterilized instruments and equipments. Individuals sharing needle while using illegal drugs easily transmitted these diseases to each other. Unprotected sex is another common method of transmission of blood borne disease. Common blood borne disease includes hepatitis C ,HCV, HBV and HIV. FOOD AND WATER TRANSMISSION: Many diseases are transmitted by contaminated food that has not been cooked as refrigerated properly and water has been contaminated with human or animal fecal material. E.g. Tuberculosis, botulism and staphylococcal and streptococcal infections. FECAL – ORAL TRANSMISSION: Occurs most often among health care and day care workers (who frequently change diapers) and by careless food handlers. GOALS FOR DENTAL OFFICE INFECTION CONTROL: The most important step is to depine and set general goals for infection control in the office. ADA recommended 4 general goals that form the bases of the “golden rules” for infection control. I. To ensure each patient that he / she will not receive any residual blood, saliva, or microorganisms from other patients treated in the office (No patient to patient contamination). II. To ensure each patient that all office personnel will use appropriate universal precautions to minimize possible body fluid transfer between office personnel and the patient. (No health care workers to patient body fluid transfer).
  6. 6. III. To ensure each patient that the level of general office cleanliness and sanitation will be maintained within the professional standards of care in dentistry and community public health expectations in general. IV. To ensure each patient that office will use only the mast effective infection control materials and methods available without compromising their use for reasons of office convenience, efficiency or cost (use the best even if last a little more and follow the directions). OBJECTIVES: 1) Decrease the number of pathogenic microorganisms to level where normal body can prevent infection. 2) Break cycle of infection between dentist to patient. 3) Treat all patients and instrument as though they could transmit infection. 4) Protect patient and personnel from infection DISEASE TRANSMISSION IN DENTAL OFFICE 1) Patient to dental team 2) Dental team to patient 3) Patient to patient 4) Dental office to community (including dental team’s family) 5) Community to dental office to patient. Patient to dental team: Microorganisms from the patient’s mouth can be passed to the dental team through the following three routes. a) Direct contact b) Droplet infection c) Indirect contact Infection control measures that help prevent disease transmission from the patient to the dental team member include 1) Gloves 2) hand wash 3) masks 4) rubber dams 5) patient mouth rinses.
  7. 7. A patient may be a carrier of disease. A carrier is one individual who harbors the specific organisms of a disease in the body without obvious symptoms and is capable of transmitting the disease to others. Dental team to patient: The spread as disease from a member of the dental team to a patient is very unlikely to occur. If proper procedures are not fallowed them disease transmission can occur. If the hands of the dental team member contained lesions as if the hands were cut while in the patients mouth transferring microorganisms. Droplet infection of patient occur if the dental team member had cold. Dental office to community: Microorganisms can have dental office and enter the community in a variety of ways. E.g. contaminated impressions may be sent to the dental laboratory, as contaminated equipment may be sent out for repair. Office to community transmission can also occur if members of the dental team transport microorganisms out of the office on their clothing as in their hair. RECOMMENDATIONS AND REGULATIONS FOR INFECTION CONTROL IN THE DENTAL OFFICE: Some government agencies and professional organizations have a direct influence on dentistry, infection control and other health care safety issues. Some have regulatory rules and some have advisory. Recommendations are made by individual or group that are advisors and have no authority for enforcement. Regulations are made by groups that have the authority to enforce compliance with the regulations. Enforcement may include penalty fines imprisonment or revocation of professional licenses. ASSOCIATIONS AND ORGANIZATIONS:
  8. 8. Professional organizations are a valuable resource for infection control and other professional information. 1) American dental association: The ADA is the professional organization for dentists. The ADA periodically updates its infection control recommendations as new scientific information becomes available. ADA also publishes reports or emerging issues of interest to the dental community. 2) Organization for safety and asepsis procedures: The organization is compared of dentists, hygienists, dental assistants, government representatives, dental manufacturers, university professors, researchers and dental consultants. OSAP is excellent resource for information on infection control, injury presentations and occupational health issues. OSAP publishes its official infection control recommendations actually to keep pace with new information and distributes information monthly on the form of news letter, reports, position papers and press releases. GOVERNMENT AGENCIES: 1) Centers for disease control and prevention: Most infection control procedures practiced in dentistry are based on recommendations made by CDC. CDC does not have the authority to make laws but many local, static and federal agencies use CDC recommendation to formulate laws. 2) Food and drug administration: Is a part of US department of health and human services. In addition to infection control FDA regulates the manufacturing and leveling of medical devices (such as sterilizers and biologic and cleaning solutions, gloves, masks, surgical gowns, handpieces, liquid sterilants and disinfectants and of antimicrobial hand washing agents and mouth washes).
  9. 9. The purpose of FDS is to assure the safety and effectiveness of medical devices by requiring “good manufacturing practices” and reviewing the devices with associated labeling. 3) Environmental protection agency: Is associated with infection control by attempting to ensure the safety and effectiveness of liquid sterilants and disinfectants. They also are involved in regulating medical work after it leaves the dental office. EPA registration number will be given to the product only if the product is scientifically proved to be safe. 4) Occupational safety and health administration: It is a regulatory agency that is a division of the US department of labor. OSHA’s responsibility is to protect the U.S. workers from physical, chemical or infections hazards in the workplace. OSHA accomplishes its mission by establishing protective standards, enforcing those standards and offering technical assistance and consultation programs. Certain terminologies used by OSHA: • Exposure is defined as “specific eye, month, other mucous membrane, non intact skin or parenteral contact with blood or other potentially infections material that results from performance of employees duties”. • Work practice control and engineering controls – are term describe precaution and use of device to reduce contamination risks. E.g. careful handling of sharp instruments, use of high volume suction. • Personal protective equipment – term used for batters such as gloves, gowns and masks.
  10. 10. • Housekeeping – term that relates to clean up of treatment soiled respiratory equipment, instruments. Counters and floors as well as to management of used gowns and waste. Following is the summary of current OSHA regulations specifying what employees must furnish, directions employers must proved and compliance required of employer. 1) Provide Hepatitis B immunization to employees without charge within 10 days of employment. 2) Require that universal precautions be observed to prevent contact with blood and other potentially infections materials. Saliva is considered to be a blood contaminated body fluid in relation to dental treatment. 3) Implement engineering controls to reduce production of contaminated splatter, mists and aerosols. E.g. rubber dam, high volume suction scaling instruments instead of control for respiratory infection. 4) Implement work pta practice control precautions to minimize splashing spatter as contact of base hands with contaminated surfaces. E.g. when using a brush to scrub instruments, hold instruments will down in the sink, place the bristles on upper surface of instrument and brush away from you. Never contact telephones, switches, pens, down handles with soiled gloves. 5) Provides facilities and instructions for washing hand after removing gloves and for washing other skin immediately or as soon as feasible after contact with blood or other potentially infections material. 6) Prescribe safe handling of needles and other sharp items. 7) Prescribe disposable of single use needles, wires, carpules and sharps as close to the place of use as possible, as soon as feasible is head
  11. 11. walled leak proof containers labeled that are closable from which needle cannot be easily spilled. 8) Contaminated reusable sharp instrument must not be stored / processed in a manner that requires employees to reach hand into containers to retrieve them from soaking pens. Use biohazard labeled as red pens that are leak proof and puncture resistant. 9) Prohibit eating, drinking, handling contact lenses and application of facial cosmetics in contaminated environment such as separatories or clean up areas. Base storage of food and drinks in refrigerators or other spaces where blood or infectious material are stored. 10)Place blood and contaminated specimens e.g. teeth, biopsy specimen, culture specimen in a suitable closed containers. Surface of all containers must be cleaned enclosed in another clean red or biohazard labeled container. 11)At no cast to employees, provide them with necessary personal protective equipment and clear directions for use e.g. gloves, masks etc. 12)Ensure that employees correctly use and discard personnel protective equipment (PPE) or prepare it for reuse. Provide adequate facility to discard gowns or laundry in location where they are used. 13)As soon as feasible after treatment attend to house keeping requirements (operating asepsis) that are subjected to contamination. 14)Provide a written schedule for cleaning and then decontaminating procedures. 15)Contaminated requirement that require service must first be decontaminated or a biohazard label must be used to indicate contaminated parts.
  12. 12. 16)Contaminated sharps are regulated waste, discarded in hard walled containers. Containers contaminated outside must be placed in a secondary container. 17)Place reusable contaminated sharp instrument into a basket in a hard walled container for transportation to the clean up area. Personnel must not reach hands into containers of contaminated sharps. 18)Provide laundering of protective garments used for universal precautions at no cast to employees. OSHA MANDATED TRAINING FOR DENTAL EMPLOYEES: The following must be available to all dental employees. • A copy of blood borne pathogens standard and specific information regarding the meaning of standard. • Information about blood borne pathogens, both the epidemiology and symptoms of the diseases. • Information about the cross contamination pathways of blood borne pathogens. • A written copy as means for employees to obtain the employer’s written exposure control plan. • Information on the tasks, category placement of employee classification and how each is identified in relation to blood borne pathogens and other potentially infectious materials. • Information regarding the hepatitis B vaccine. • Information about exposure reductions, including PPE, work practices, standard precautions, including universal precautions and engineering practices.
  13. 13. • Information about the selection, placement, use, removal, disinfection, sterilization and disposal of PPE. • Information about what to do and whom to contact if an emergency involving blood as potentially infectious material arises. • Information about the past exposure evaluation and follow up the employer provides. • A copy of the OSHA hacast communication standard. • Material safety data sheets (MSDs) and information about labeling and hazardous waste. • Opportunity to the employees to ask questions of the individual giving the information. CATEGORIES OF EMPLOYEES: 1) Category I: Routinely exposed to blood, saliva or both. E.g. Dentist, dental hygienist, dental assistant, sterilization assistant, dental laboratory technician. 2) Category II : May on occasion exposed to blood, saliva or both. E.g. receptionist or office manager who may occasionally clean a treatment room or handle instruments or impressions. 3) Category III: Never exposed to blood, saliva or both. E.g. Financial manager, insurance clerk, or computer operator. IMPORTANT INFECTIOUS DISEASE TRANSMISSIBLE BY THE ORAL CAVITY: 1) AIDS:
  14. 14. AIDS is a severe condition caused by infection with the human immunodeficiency virus (HIV-1). AIDS was reported as a new clinical disease in the summer f year 1981 and CDC now estimates that approximately 40 million people have been infected with HIV world wide. Causative organism - HIV is a member of a group of RNA viruses called retrovirus. Type I – Most common world wide cause of HIV Type II – in Western Africa ROUTES OF TRANSMISSION: A) Sexual contact (heterosexual or homosexual) The virus from an infected person’s blood, seminar vaginal secretions enter the blood circulation through tiny breaks in the rectum, vagina or penis. B) Blood and blood products: 1) Injection drug users: contaminated, shared needles carry the infection. 2) Transfusion and use of blood products by patients with blood disorders. 3) Occupational accidental injuries: low risk of infection. C) Perinatal: 1) Placenta: virus can be transmitted across placenta. 2) During delivery: exposure during passage through infected genital tract. 3) Postnatal : through breast feeding. INDIVIDUALS AT HIGH RISK OF INFECTION: a) Sexually active homosexual or bisexual man having multiple partners without practicing safe sex. b) Users of intravenous drugs particularly when sharing contaminated needles.
  15. 15. c) Recipients of blood transfusions or blood products. d) Male and female prostitutes who do not practice safe sex. e) Recipients of HIV-1 infected organ transplants. f) Females artificially inseminated with HIV-1 infected semen. g) Infants born to HIV-1 infected mothers. h) Infants fed breast milk from HIV-1 infected mothers. LIFE CYCLE OF THE HIV-1: HIV-1 is a retrovirus having RNA as care genetic material. Enzyme reverse transcriptase is essential for replication. II. Establishment of infection: A. Binding to a target / host cell: 1) HIV-1 enters the body and passes by way of the blood to a target cell surface where it binds to a specific cellular receptor CD4+. 2) Target cells that have CD4+ receptors include T-helper lymphocytes, monocytes, macrophages and certain neurons and gilial cells of the brain tissue. B. Entry through wall of the target / host cell : Fusion occurs between virion and the target cell membrane and the virus becomes uncoated. Only the viral RNA and enzymes enter the cell. C. Reverse transcription : 1) Viral RNA is changed into single-stranded DNA by the enzyme reverse transcriptase. Single stranded DNA is these translated to double stranded DNA which is called the provirus. 2) The provirus migrates to the nucleus of host cell, enter the nucleus and becomes permanently integrated with the host DNA. D. Infection is established E. Latency period The integrated proviral DNA remains latent for long period, but they induce the production of new viruses pentacle within the lymphocytes.
  16. 16. Virus that can infect and destroy more lymphocytes leading to depletion in T4 cells which leads to variety of infections and neoplasm due to immunocompromised state (below 200mm3 ). This end stage of HIV infection is called AIDS. In patients with advanced HIV disease, as many as 109 new virions are produces each day and as many as 2x109 CD4 cells turn over per day. Occupational exposure to HIV many occur, percutaneous exposure involves needles carrying HIV infected blood. Risk of acquiring HIV via a percutaneous exposure is 0.3% whereas after a mucocutaneous exposure, risk is about 0.09%. Epidemiology : AIDS appears to have originated in Africa, where serologic evidence suggests that it has been present for atleast 2 decades. An estimated 42 million people world wide have been infected with HIV since the onset of the pandemic. No end is in sight for the HIV pandemic because here is no presently available drug that will inactivate the virus in vivo. Because there is no effective vaccine, we must depend upon education and behavioural change to control the disease, uniqueness of this infection is based upon the fact that HIV attacks cells of the immune system. Thus event eventually leads to a progressive and irreversible immunosuppression by production of more virus and further killing of T4 helper lymphocytes, the cells that moderate immune system. The subsequent immunodeficiency leads to a opportunistic infections, malignancies and autoimmune disease which then lead to death. Progression of HIV-AIDS : Acquiring HIV infection Acute illness (fever, rash, joint and muscle pain, sore throat) Pre-AIDS AIDS Death Window period Asymptomatic Symptomatic
  17. 17. CLASSIFICATION OF HIV INFECTION AND AIDS : CDC gave the classification for HIV infection in 1993 CD4 count A Asymptomatic disease B Minimally symptomatic (not A or C category) C AIDS indicator condition > 500/mm3 A1 B1 C1 200-499mm3 A2 B2 C2 < 200/mm3 A3 B3 C3 Co-relation between CD4 count and HIV associated disease : > 500 cells/mm3 200-500 cells/mm3 < 200 cell/mm3 - Acute primary infection - Persistent generalized lymphadenopathy - Recurrent vaginal candidiasis - Herpes zoster - Pulmonary TB - Oral hairy leukoplakia - Idiopathic thrombocytopenic perpura - Ropharyngeal candidiasis - Pneumocystitis carinii pneumonia - Mucocutaneous herpes simplex - Oesophageal candidiasis - HIV associated wasting disease - Peripheral neuropathy < 100 cells / mm3 - Non hodgkins lymphoma - Cerebral toxoplasmosis - HIV associated dementia <50 cell /mm3 - CMV retinitis - Burkitt’s lymphoma Clinical course of HIV-1 infection : A detectable antibody level usually can be detected within 1 to 3 months after exposure to HIV-1 virus. Antibody presence indicates infection.
  18. 18. I. Incubation period : Ranges from the tissue of infection until the time when symptoms of AIDS are evident which may by 15 years or longer. A. Initial infection : After exposure, one half of these infected will have flue like symptoms within 2 to 6 weeks. They are often unsuspected as associated with HIV-1 infection. 1) Symptoms – fever, lymphadenopathy, pharyngitis, fatigue, muscle pain and a skin rash. 2) Viremia – within 2 to 4 weeks after the initial infection high levels of virus occur related to dissemination and development of antibody. B. Early HIV-1 infection : 1) CD4 > 500 cell/mm3 2) Symptoms : no symptoms usually but if any lymphadenopathy and dermatologic lesions. 3) Oral lesion : More common in later stage herpes simplex labialis, apthous ulcers. Hairy leukoplakia – indicator of HIV-1 infection. C. Intermediate stage : 1) CD4 count : 200-500 cells / mm3 2) Symptoms : skin and oral lesions become more common. Recurrent herpes simplex, varicella zoster, fever, weight loss, candidiasis, myalgia, headache, fatigue. 3) Oral lesions : More common candidiasis is considered to be indicator of pneumocystis carinii pneumonia. D. Late stage disease : AIDS 1) CD4 count - 200-500 cells / mm3 2) Symptoms : AIDS indicator condition Opportunistic infections
  19. 19. Constitutional disease : HIV-1 wasting syndrome, long term fever, sever weight loss, anemia, chronic diarrhoea, chronic weakness are all effects of loss of immune response. 3) Encephalopathy : organic mental disorders Disabling cognitive or motor dysfunction may develop with symptoms of apathy, inability to concentrate, poor memory and depression. 4) Neoplasms : Kapsoi sarcoma, non-hodgkin’s lymphoma. Oral manifestations : • Persistent oral candidiasis white curd like patches over tongue. • Chelitis at angles of the lips. • Painful herpes stomatitis • Kaposis sarcoma – sarcoma of capillaries – often seen over palate as red brownish to purple blotches. • Gingivitis and periodontitis which is recurrent • Atypical periodontitis associated with HIV Serology for HIV infection : HIV infection is detected by blood tests 1) ELISA 2) Western blot test 3) Floroscent antibody tests These tests detect the Abs formed against the virus. Test for anti HIV antibody are often positive within 3 months after infection, most are positive by 6 months. A second positive test is necessary to confirm the serologies. Other methods : Direct PCR – polymerase chain reaction HIV risks for clinical personnel :
  20. 20. Of all American health care workers injured by needles and sharp instruments used to treat HIV infected persons only 0.3% as less have been infected with HIV. HIV infection has been developed in a nurse and technician spattered with HIV infected blood. Therefore personnel are required to protect eyes, mucosa, skin and hands from spatter and direct contact with blood and blood contaminated body fluids during dental treatment of all patients. Precautions also must be made to minimize risk of injuries with sharp instrumentation. Patients with AIDS may harbor transmissible respiratory infection such as TB and CMV which are generally atypical in these patients. HIV risks for dental patients : With proper use of infection control measures in dental practice, the risk of dental patients of contracting HIV from office personnel is low. Only one unique circumstance has come to light, where a group of 6 patients was found to be infected with the same strain of HIV that infected the florida dentist who treated them. HIV data related to infection control : 1) Unlike HB virus, HIV usually has been found in very low levels is blood of infected persons. This is especially there of asymptomatic persons who are the most difficult to recognize and would be most likely to be treated in private office. 2) HIV was detected in only 28 of 50 samples of blood from infected persons. In saliva from infected persons, HIV was detectable in only 1 of 83 samples. 3) In dried infected blood, 99% of HIV has been found by CDC investigators to be inactive in approximately 90 minutes. However when wet virus may survive for 2 or more days.
  21. 21. 4) HIV is killed by all methods of sterilization. When used properly, all disinfectants except some quaternary ammonium compounds are said to inactivate HIV in less than 2 min. 5) HIV has been transmitted by blood contaminated fluids that have been heavily splattered or splashed. However aerosols produced during dental treatments, have not been found to transmit HIV infection. 6) Barriers have proven successful protecting dental personnel to hospital dentistry. VIRAL HEPATITIS : Infective inflammation of the liver termed as hepatitis viruses cause a variety of types of hepatitis. - Hepatitis A - Hepatitis B - Hepatitis C - Hepatitis D (δ) - Hepatitis E New viruses have been found • Non ABCDE • HGV Features of hepatitis virus : Virus group Hep V entero B hepanete C Flavivirus D incomplitic RNA Nucleic acid Incubation week SPREAD Facies Blood Saliva Sexual Epidemiology : In post transfusing patients or injection during users
  22. 22. In the 8 years after AIDS was recognized 38,000 persons developed the disease. During the same period an estimated 38,400 died from Hepatitis B, related cirrhoses or liver carcinoma. Hepatitis B : Described in 1965, caused by hepatitis B virus. It is a DNA virus. The virus is composed of an outer compartment of HBsAg and an inner compartment of HBcAg – inside the core particle is a single molecule of circular, partially double stranded DNA endogenous DNA polymerase and HBeAg. Spherial and tubular particles of HBsAg circulates in infected blood in great numbers. • Anti HBs antibody to HbsAg is responsible for long term immunity. • Anti HBs antibody to care antigen develops in all patients with HBV infection to persists indefinitely. • The HBeAg correlates with HBV replication and high infectivity. Symptoms and clinical findings : Nausea, vomiting, chronic fatigue, mental depression, fever, joint aches, jaundice, possible rash or diarrhoea. Only 2 to 10 patients infected with hepatitis B show symptoms, the remaining 8 persons are usually unaware of their infection. For this reason, it is impossible to detect most hepatitis B infected person from medical history. Whether infected prson are asymptomatic or not they can transmit hepatitis B virus. Chronic carrier state is seen. Modes of transmission : 1) Percutaneous : dental treatment involves use of small sharp instruments. Accidents with sharp needles.
  23. 23. 2) Non percutaneous : transfer of infections body secretions, saliva, blood and crevicular fluid. 3) Perinatal exposure 4) Sexual exposure 5) Infection from blood transfusion and blood products. Other types : 2) Hepatitis A : Highly infections includes preicterus phase and icteric phase. Mode of transmission : Farco-oral route seen generally in overcrowding and poor sanitation. Chronic carrier state analogus to hepatitis B is not there. 3) Hepatitis C : (Non A / Non B) Occurs without jaundice Mode of transmission : Blood, saliva, direct percutaneous exposure, perinatal transmission possible, intravenous drug abuse. 4) Hepatitis D : It is a RNA defective virus which has no independent existence. It can infect individual simultaneous with HBV or it can super infect those who are already chronic carrier of HBV. Mode of transmission : Parental, IV drug abuse, similar to hepatitis B. 5) Hepatitis E : Epidemic non A, non B Fecal oralmode of transmission Clinical course and distribution are like those of hepatitis A. PREVENTION AND CONTROL : Hepatitis A : 1) Sanitation and personal hygiene
  24. 24. Because principle means of transmission is by feces, prevention an that level is indicated. a) Public health control of food handlers and of water contamination. b) Personal hygiene control through proper hand washer by patient as well as health care personnel involved in patient care. 2) Application in dental setting Instrument sterilization, use of disposable materials, and all related precautions for persons and objects contacted by the patient. Hepatitis B : Hepatitis is a critical occupational hazard for dental personnel because of their close association with the potentially infected body fluids of patients. Every health care personnel should be immunized so that the possibilities of disease acquisition and transmission can be minimized. I. COMPREHENSIVE PREVENTIVE PROGRAM : A. Eliminate transmission during infancy and childhood. 1) Prenatal testing of all pregnant women for HBsAg. 2) Universal immunization of infants and childrens to be accomplished during routine health care visits when vaccinations are usually administered. 3) Immunization of uninfected children. 4) Immunization of adolescents and adults, particularly those at high risk. B. Enforce blood bank control measures : 1) Screening of donors, rejection of individuals who have a history of viral hepatitis. 2) Strict testing for all donated blood. C. Enforce sterilization or use of disposable syringes and needles. II. ACTIVE IMMUNIZATION : the vaccines
  25. 25. Active immunity : occurs by stimulation of an individuals own immune response. Protection is provided only after a latent period. However long term immunity is provided. Eg. of active immunization are actual acquisition of the disease and vaccination. Passive immunity : Occurs by transferring performed antibodies from an actively immunized host. Protection provided is transitory and onset is immediate. Eg. infection of immunoglobulin Ig or HBIG. Hepatitis B vaccine are administered in three doses, the first at the onset these at 1 and 6 months. The vaccine is given in deltoid muscle for adults and childrens and in the anterolateral thigh muscle for infants and neonates. A) Plasma – derived HB vaccine Eg. Heptavax-B. prepared by using purified HBsAg from plasma of chronic HBsAg carriers B) Recombinant : DNA HB vaccine Recombinant DNA technology has been used to synthesize HBsAg in culture of saccharomyes arevisiae a yeast. POST EXPOSURE PROPHYLAXIS : A) Indication for prophylaxis : 1) Newborn of HBsAg – positive mother 2) Significant hepatitis B exposure to HBsAg positive blood. B) Hepatitis B immune globulin : C) Procedure for newborn of HBsAg – positive mother. HBIG and HBV vaccine intramuscularly within 12 hours of birth subsequently as recommended for a specific vaccine. 3) HERPES VIRUS DISEASE
  26. 26. Herpes virus produce disease with latent, recurrent and sometimes malignant tendencies. Abbreviation Name of the virus Infection VZV Varicella-zoster Varicella (chickenpox) Herpes zoster (shingles) EBV Epastin-Barr EBV mononucleosis HCMV Human cytomegalovirus Cytomegalovirus disease Fetal infection HSV-1 Herpes simplex virus Herpes labialis HSV-2 Types 1 and 2 Herpetic gingivostomatitis Herpetic keratoconjunctivitis Herpetic whitlow Encephalitis Neonatal herpes HHV-6 Human herpes virus 6 Mononucleosis like rash HHV-7 Human herpes virus 7 Febrile illness HHV-8 Kaposis Kaposis sarcoma KSHV Sarcoma herpes virus VIRAL LATENCY : The herpes virus have the ability to travel along sensory nerve pathways to specific ganglia. The specific ganglia are usually the following A) Herpes simplex type 1 (HSV-1) travels to the trigeminal nerve ganglion. B) Herpes simplex type 2 (HSV-2) travels to the thoracic, lumbar and sacral dorsal root ganglia. C) Varcella-zoster virus (VZV) goes to the sensory ganglia of the vagal, spinal and cranial nerves. SEQUENCE OF EVENTS : PRIMARY INFECTION 1) Exposure of person to the virus at the mucosal surface or abraded skin. 2) Replication begins in the cells of dermis and epidermis
  27. 27. 3) Infection of sensory and autonomic nerve endings. 4) Virus travel along the nerve to ganglion. 5) After primary disease resolves, the virus becomes latent in the ganglion. 6) Reactivation at later date is precipitated by a stimulus, such as sunlight, immunosuppression, infection or stress. 7) Virus transfers along the nerve to the body surface where replication takesplace and a lesion forms. RESPIRATORY VIRUSES : Transmission is by way of small particle, aerosols, droplets and large particles and by direct contact or famites. Common cold caused by variety of viruses is primary a nuisance but can result in loss of work time. Common cold most readily transmitted by fomites or autoinnoculation. These viruses may cause pharyngitis. Adenovirus : common cause of respiratory illness. Conjunctivitis may accompany the respiratory symptoms or occur as primary symptoms. Enterovirus : characterized by rashes and upper respiratory tract infection. Mycobacterium tuberculosis : Transmission is by way of inhalational of tubercle bacilli ladese aerosoliced droplets with lungs becoming the initial site of infection. A recent concern of the immunocompromised patients as well as for dental personnel is transmission of multidrug resistant mycobacterium tuberculosis. INFECTION CONTROL : Universal precautions : Since not all the patients with infectious diseases can be identified by medical history, physical examination or readily available laboratory tests routinely in dental practice. The CDC has introduced the concept of universal precautions i.e, treating of all body fluid from all patients as
  28. 28. though infected with blood borne disease agents and this has been incorporated as a rule into the blood borne pathogens standard by the occupational safety and health administration (OSHA). The basis for this approach to infection control lies in the fact that many infectious diseases, including the blood borne diseases like HIV, hepatitis B, C, and D are commonly asymptomatic. Thus because it is impossible to identify all those who may be carrying such infectious disease agents, the same infection control procedures must be used for everyone to maintain protection for both the patients and the dental team. Universal precautions are as follows : 1) Medical history 2) Barrier technique 3) Limiting contamination 4) Washing and care of hands 5) Handling of sharp instruments and needles 6) Sterilization and disinfection / instrument processing 7) Surface asepsis 8) Aseptic technique 9) Disposal of waste materials Medical history : In dentistry it has been recommended routinely that a comprehensive medical history be taken for each patient and to be reviewed and updated at subsequent appointments. It serve several purposes 1) To detect any unrecognized illness that require medical diagnosis and care. 2) To identify any infection or high risk that may be important to a clinical person exposed during examination treatment, or clean up procedures.
  29. 29. 3) To assist in managing and caring for infected patient. 4) To reinforce use of adequate infection control procedures bearing in mind that general history taking is not capable of detecting all infections persons. II. PROTECTING BARRIER TECHNIQUE : Dental assistant has constant exposure to saliva and blood during intraoral / invasive dental procedures. Barriers such as protective eyewear, face masks, disposable gloves and appropriate uniforms should be used routinely to minimize exposure. Gloves : Gloves are used as a barrier to microorganisms. Gloves must be worn by dentist, dentist, dental assistant and dental hygienist during all treatments that may involve contact with the patients blood, saliva or mucous membranes or with contaminated items or surfaces. After contact with each patient, gloves must be removed, hands must be washed and these regloved before treating another patient. Repeated use of single gloves by disinfecting them is not acceptable. Exposure to disinfectants or other chemical often causes defects in gloves thereby diminishing their values as effective barriers. CRITERIA FOR SELECTION OF TREATMENT / EXAMINATION GLOVES : A. Safety factor : 1) Effective barriers 2) Impermeable to patients saliva, blood and bacteria 3) Strength and durability to resist tears and punctures 4) Impervious to materials routinely used during clinical procedures. 5) Nonirritating or harmful to skin, use nonlatex gloves when patient or clinician is allergic. B. Comfort factors :
  30. 30. 1) Fit hand well, no interference with motion, glove cuff extends to provide coverage over cuff of long sleeve. 2) Tactile sense minimally decreased. 3) Taste and odour not unpleasant for patient. TYPES OF GLOVES : A. Material : 1) Latex 2) Non latex : neoprene, block copolymer, vinyl, N-nitrile. B. For patient care : 1) Nonsterile single – use examination / treatment latex, nonlatex 2) Presterilized single – use surgical, latex, nonlatex 3) Hypoallergic gloves 4) Powderless gloves 5) Flavoured gloves C) Utility gloves : 1) Heavy duty, latex, nonlatex – heavy nitrile gloves (puncture resistant) 2) Plastic – food handler’s glove to wear as overglove D) Dermal underglove : to reduce irritation from latex or nonlatex. E) Heat resistant gloves 1) Sterile surgical gloves : The best fitting and generally the most expensive disposable gloves. Used when maximum protection is indicated. 2) Latex gloves : These are most commonly used in dentistry. An occasional hypersensitivity to the latex has been reported. Inadequate changing of hand prior to gloving has proven to be another cause of dermatitis. If the hypersensitivity exists the practiouer can opt for a glove without cornstarch, use a vinyl or neoprene gloves or use cotton glove liners under the latex gloves.
  31. 31. Pinholes are present under all types of gloves and latex gloves are no exception. The danger in pinholes is that microorganisms can penetrate through minute openings in the latex and multiply. 3) OVERCILOVES : Gloves are placed over the latex as vinyl gloves during a procedure to prevent cross contamination. They are big loose gloves that do not have the tactile touch that the latex and vinyl gloves have but they quickly fit over the gloves to obtain something in sterile area. They are not used as a examination gloves. They should be discarded after every use. NON DISPOSABLE GLOVES : Heavy utility gloves used during handling contaminated instruments or supplies when using chemical sealant and during cleaning of treatment area. Utility gloves can be purchased that can be washed, sterilized, disinfected and used and that are puncture resistant. PROCEDURE FOR USE OF GLOVES : A) Mask and eyewear placement prior to hand washing and glaring to prevent the need for manipulating the mask around the face and hair after washing the hands. B) Pregloving hand wash : Hands must be dried throughly to control moisture inside gloves and thus discourage growth of bacteria. C) Glove placement : Always glove and deglove in front of the patient. A patient may need assurance that gloves are new and used only for that appointment. D) Avoiding contamination. Keep gloved hands away from face, hair, clothing, telephone, patient records. Clinical stool and all other equipments that have not been pre disinfected. E) Torn, cut or punctured gloves – Remove immediately wash hands thoroughly and wear new gloves. F) Removal of gloves.
  32. 32. FACTORS AFFECTING GLOVE INTEGRITY A) Length of time : 1) New pair for each patient 2) Total time should be no longer than 1 hour. 3) When glove develops sticky surface – reglove. B) Complexity of procedure Certain procedures more likely to promote perforations, especially when sharp instruments are used. C) Size of glove When too long, extra material at the finger tips can get turn or in the way picking up of small object is difficult especially sharp instruments. D) Storage of gloves - Keep in cool, dark place - Exposure to heat, sun increases the potential for deterioration and perforations. E) Hazards from hands – like rings F) Pressure of tissue Sires, was ring too fast increases the risk of grove damage. G) Agents used : Certain chemicals react with the grove material, eg petroleum fully, alcohol and products made with alcohol tend to break down the from integrity. Later hypersensitivity : Latex sensitivity is to protein allergens and additives used when commercial latex is prepared. Equipment that may contain latex. - Groves - Lead apron cover - Masks - Rubber polishing cup - Rubber dun - Bike blocks. Harmful reaction to latex groves and other later products :
  33. 33. Symptoms Conditions 1) Hands become dry, red itchy and sometimes cracked Irritant contact dermatitis 2) Redness, initial itching, vesicles appear in areas of contact within 24 to 48 hours followed by dry skin with fissures and sores Type IV hypersensitivity (delayed hypersensitivity) 3) Runny nose, sneezing, itchy eyes, scratchy throat, asthma and in rare case anaphylaxis Type I hypersensitivity (Immediate type hypersensitivity) LIMITATION OF GLOVES : • Offers with protection against injuries with sharp objects instruments needles and scalpel blades. • Do not reuse utility gloves of they are peeling, cracking, discolored, tarn, punctured. OVERGARMENTS: B) PROTECTIVE CLOTHING: The purpose of protective clothing is to protect the skin and under clothing from exposure to saliva, blood, aerosol and other contaminated materials. Protective clothing includes uniforms, laboratory coats, gowns and clinic jackets. Guidelines for use of protective clothing: • Because protective clothing can spread contamination, it is not warn out of the office for any reason. • Protective clothing should be changed at least daily and more often is visibly soiled.
  34. 34. • If a protective garment becomes visibly soiled or saturated with chemicals or body fluids, it should be changed immediately • Protective clothing must be warn the staff lounge areas as when workers are eating or consuming beverages. Protective clothing requirements: • Protective clothing should be made of fluid resistant material. Cotton or disposable jackets or gluons are satisfactory for routine dental procedures. • To minimize the amount of uncovered skin, clothing should have long sleeves and high neck line. • The design of sleeve should allow the cuff to be tucked inside the band of glove. • During high – risk procedures, clothing must cover dental personnel at hest to the knees when seated. • Buttons, trim, zippers should be kept to minimum as they can harbor pathogens. • No pockets. Pockets are too readily available for placing contaminated objects. Gloved hands should not be used for touching contaminated objects placed in pockets. Handling contaminated laundry: Contaminated laundry must be labeled with the universal biohazard label. Must be laundered in the office or sent to laundry service. II) Hand and Hair Covering: A) Hair must be warn off the shoulder and fastened back away from the face. When longer it should be held within the head cover. B) Facial hair must be covered with face mask as a face shield. BARRIERS:
  35. 35. Any area that can be covered where contamination is possible during dental treatment should be covered. Barriers have been made specially for areas that have been hard to disinfect or sterilize in past. In the operatory, the patient dental chair, the light handless and operating switdes, hand piece, air wakes syringe, high volume evaluator, saliva ejector and tubing are covered with barriers. Plastic dry cleaning bags are non-expensive and can be used to cover the dental chair. FACE MASK: A mask is warn over the nose and mouth to protect the person from inhaling infectious organisms spread by aerosol spray of the hand piece or air water syringe and by accidental splashes. Mask efficiency : 1) Filtration standard mask blocks filtration of particles as small as 3 µm with a filter efficiency greater them 95%. 2) Proper fit over the face is a must to protect against inhaling aerosols. Characteristics by ideal mask: • No contact with the wearers nostril or lips • Has high bacterial filtration efficiency rate. • Fits smugly around the entire edges of the mask, convenient to put and remove. • Does not collapse during wear as when wit • No fogging of eyewear. • Made of materials that does not irritate skin or induce reaction. Materials used for mask: Material Effectiveness 1) Paper, Cloth, Foam Less effective 2) Glass, synthetic fibers Better 3) Plastic face shield + face mask For total effectiveness
  36. 36. Use of mask: 1) Adjust the mask and position eye wear before a scrub or hand wash. 2) Use face mask for each patient more frequently when it becomes wit. 3) Keep the mask on after completing a procedure while still in the presence of aerosols. Particles smaller than 5 µm remain suspended longer than do larger particles and can be inhaled directly. 4) Mask removal – grasp sick elastic or tic strings to remove. - Never handle the outside of a contaminated mask with gloved as bane hands. 5) Mask should be disposed off after each use and not left hanging around the neck. PROTECTIVE EYE WEAR: Important to prevent physical injuries and infection to the eye contamination can be induced from saliva, plaque, carious material, aerosol, spatter etc. • Advisable to use protective eye wear by all involved dental team member and patient. General fractures of acceptable eye wear: - Wide coverage with side shields - Shatter proof, made of strong sturdy plastic - Easily disinfected - Surface area smooth - Frames and less should not be distasted by disinfectants used. Types of eye wear: 1) Goggles: Especially necessary for protecting during laboratory work. 2) Eye wear with side shields. 3) Eye wear with covered frames / Face shields.
  37. 37. • Eye wear should provide front, top and side protection. • Eye wear is also used to protect eyes from high intensity lights used for curing dental materials. These glasses are colored arrange for protection. RUBBER DAM: Rubber dam isolation has shown to significantly reduce infectious particles in aerosols. Used in combination with a pre-operative rinse of chlorhexidine gluconate. The contamination can be further reduced. Additionally rubber dam use reduces the extent of contact of the operator hands with the patient’s mucosa. Thus when used be conjugation with other barriers dam usage minimized transmission of blood barn pathogens from patients mouth. LIMITING CONTAMINATION: Three principles of limiting contamination by droplet and spatter are the use of high volume evacuation, proper patient positioning and rubber dam. Autiseptic mouth rinse (0.12% chlarhexidine gluconate) helps in reducing the total number of microorganisms. High volume evacuation : It is an effective way to minimize the spray coming from the high speed rotary hand piece and the air water syringe. Evacuation system use tips that are sterilizable or dispasable. Running water and specialized detergent deodarizers through high volume evacuation at the end of each day aids in reducing the microorganism in hoses and the trap. WASHING AND CARE OF HANDS: The hands may as a means of transmission of blood saliva and bacterial plaque from patient. By caring properly for the hands, using effective washing procedures and following basic rules for glaring, primary crass contamination can be controlled.
  38. 38. A) Finger nails : Maintain clean, smoothly trimmed short finger nails with week cared for cuticle to prevent breaks where microorganisms can enter. - Effect of short nail makes hand washing more effective because microorganisms that harbor under nail are removed. - Prevents cuts from nails in disposable gloves. B) Wrist watch and jewelry : Watch and jewelry at the beginning of the day. Hand washing principles: Rationale: Effective and frequent hand washing can reduce the overall bacterial flora of the skin and prevent the organism acquired from a patient from becoming skin resident. Purpose: - Remove surface dirt and transient bacteria - Dissolve normal greasy film on the skin - Provide disinfection with long acting antiseptic Facilities: A) Sink : 1) Use sink with a foot pedal or electronic control for water flow to avoid contamination from faucet handles. 2) For regular sink, turn on water of the beginning and leave and through the entire scrub procedure. Turn faucets off with the towel after drying hands. 3) Prevent contamination of clothing by not leaning against the sink. B) Soap :
  39. 39. 1) Use a liquid surgical scrub containing an antimicrobial agent poridone iodine has a broad spectrum of action chlarhexidine preparation can also be used. 2) Apply from a foot activated or electronic controlled dispensce to avoid contamination. Towels: 1) Obtain disposable towel dispenses that requires no contact except with the towel itself. 2) Cloth towels are not recommended. Methods of hand washing: 3 methods 1) Short scrub 2) Short standard hand wash 3) Surgical scrub. 1) Short scrub : Hand washing is recommended for the beginning of the day prior to the first gloving, and just prior to the first gloving of any series of appointment. A sterile soft brush as nail brush may be used, but hard brushing is avoided as breaks in skin could result. A) Preliminary step : - Wear protective eye wear and mask. - Wash hands and wrist briefly using liquid antimicrobial surgical scrub soap. Leave water running at moderate speed. - Clean under finger nails with arrange wood stick rinse from finger tips towards wrists. Keep hands higher than elbow during entire procedure. B) Lather hands : C) First hand : 1) Brush back and forth across nails and finger tips five times.
  40. 40. 2) Begin with the thumb, use small circular strokes on each side of thumb and each finger, then plan and back of hand. Extend fingers to gain access to each crevice and line. 3) Scrub wrist on both sides and more to forearm. 4) When completed, rinse will from fingertips on up over the wrist. D) Second hand : 1) Repent entire procedure 2) Rinse the hand and arm generously and thoroughly to wash away all transient microorganisms. 3) Dry hands thoroughly use separate paper towel for each and. E) Wear gloves : 2) Short standard hand wash : It is a general procedure for all times eg. before each patient whenever gloves are donned, after gloves are removed and before leaving the treatment area. A) Wear protective eyewear and mask. Tie hair securely at back. Remove watch and all jewllery. B) Use cool water and liquid antimicrobial surgical scrub soap. C) Lather hands, wrists and forearm quickly, rubbing all surface rigorously. D) Rinse thoroughly from finger tips across hands and wrists. E) Repeat two more times. The lathering serves to loosen the debris and microorganisms and the rinsing wash them away. F) Use proper towels for drying. Take care not to recontaminate. 3) Surgical scrub : In each has petal or oral surgery clinic, a surgical scrub is performed as the initial scrub of a day for 10 minutes and subsequent scrubs may be for 3-5 minutes, fallowing treatment of a contagious or isolated patient. A) Preliminary step :
  41. 41. 1) Wear mask and eye wear. 2) Wash hands and arms using surgical liquid antimicrobial soap to remove gross surface dirt. 3) Rinse thoroughly from finger tips across hands and wrists. 4) Use arrange wood stick to clean nails and rinse. First hand : 1) Lather the hands and arms and leave the lather on during the scrub to increase exposure time to the antimicrobial in gradient. 2) Apply surgical liquid soap and begin bush procedure. Scrub in an orderly sequence without areas previously scrubbed. 3) Brush back and forth across nails and finger tips, passing the brush under the nails. 4) Fingers and hand use small circular strokes on all sides of the thumb and each finger. 5) Continue to wrist. Apply more soap to obtain a good lather. 6) When arm is completed leave lather on. Second hand : 1) Repeat on the other arm. 2) At one half of scrub time, rinse hands and arms thoroughly first one and then the other starting at the fingertips and letting water pass down over he arm. 3) Lather and repeat. 4) Hard hand up and collapsed together, proceeds to dressing room area for gowning and gloving. OVERVIEW OF ASEPTIC TECHNIQUE: Concept of asepses is to prevent crass contamination during each appointment. 1) Remember whatever touched is contaminated 2) Directly touch only whatever has to be touched
  42. 42. 3) Use the following to control contamination a) Clean and sterilize instruments b) Protect surfaces and equipments that are hat sterilized with disposable single use covens. Discard them after every appointment. Use covers on portable items eg curing lamp handless, amalgam mixers and plastic air water syringe. c) Use a paper towel, tongs or plastic bags over gloves to open cabinets and drawers to get things not anticipated during set up. d) Scrub and disinfect noncritical surface as will as possible operatory asepsis. Preparation of operatory surfaces : - Operatory surfaces that will be repeatedly touched as soiled are best protected with disposable covers that can be discarded after each treatment. - Changing covers eliminate cleaning and disinfecting the surface, saves time and effort and expanse and can be more protective. - After each appointment discard and replace bags and cover without cleaning and disinfecting covered equipment items. Preparation of semicrotical items and noncritical items : Category Functions and eg Intra oral use Risk of disease transmission Procedure Critical Contact cut tissues as penetrate soft tissues eg Needle, scalpel, Surgical instruments, mirrors, dental explorer, periodontal probes, scalers, burs, bone chisels. Yes Very high Sterilization Bemicritical Touch mucous membrane Yes Moderate Sterilization
  43. 43. but will not touch bone or penetrate soft tissue eg Mouth mirror, amalgam condensers, handpiece, impression trays. or high level disinfection Noncritical Contact only with intact skin eg counter tops, height handle, switch, x-ray head tubing far handpiece, instrument tray No Intermediate to low level disinfection or basic cleaning. Step by step preparation of the dental chair, dental unit and instrument between appointments : 1) With hand still groved after the last treatment, remove and invert chair back cover, discard cotton rolls and other disposable materials. Remove and discard groves aseptically. 2) Wash hands with antiseptic hand soap and drug. Put on nitrile latex utility groves 3) With the used suction tip, clean saliva and debris, discard disposable suction tip. 4) Remove from anesthetic syringe the resheated needle. Discard it with all other sharp disposable items in a sharp container. 5) Before handling disinfectant disinfecting bottles, wash utility groves with antiseptic scrub, rinse and dry. 6) Spray any used bottles containers, tube and unused burs with disinfectant and wipe with a paper towel. 7) Invert, remove and discard plastic drapes from the control unit. Remove and discard covers from lamp handles and surface covering from side table. 8) For any controls and switches not covered, wet a paper towel with disinfectant spray and wipe lamp switch and controls that were
  44. 44. contaminated and side arms as dental chair, contaminated drawer handles, radiographic view box switch. 9) Use a second towel wet with disinfectant to rewet these items and leave wet. 10) Spray any contaminated fances handles, sink counter top and trash disposal opening with disinfectant and wipe dry with paper towel. 11) Wash the utility groves with strong antiseptic hand scrub as disinfectant chances, Rinse thoroughly and dry them with paper towels. Remove utility groves and rehang them in the operatory. Wash hands. Unit for next patient is prepared as fallows : 1) Pull a large clear plastic bag cover over be dental control unit. 2) Pull another bag down over the chair back and also chair arms. 3) Install suction and air/water syringe tips. Place a slander bag over each tip. Wrap autoclave tape at the tip. 4) Install sterilized handpieces. 5) Set out materials and instrument pucks, open packs carefully not to touch the sterilized instruments with bone hands. 6) Seat the patient and put on a clean mask, eye wear and gloves. Protection of complex device against contamination like cancer as, light curing units, intra oral cameral etc. must be covered with clear plastic bags – as effective Singh use protective barrier. NEEDLE STICK INJURY : This is most common injury occurring in the dental clinic during handling sharp instruments. In the event you do puncture the skin with sharp contaminated instrument do not panic. Following steps should be followed following exposure. a) Remove the instrument gently.
  45. 45. b) Wash with running water, do not scrub. Allow the hand to bleed freely for 5 months under tap water. c) If necessary induce bleeding, suck blood as in shake bit and spit squeeze blood. d) Disinfect the wound with chlorhexidine gluconate and rinse. e) Cover with dressing before continuing treatment. POST EXPOSURE PROPHYLAXIS : DISINFECTANTS: Because many operatory surfaces routinely became coated with saliva, blood, exudate and other debris and because each surface requires cleaning and disinfection when it is not feasible to use disposable covers, chemical disinfectants serve as a very useful purpose in infection control. Exposure incident occurs Employee reports it to employer Employer directs employee to HCP (Health Care Personnel) sends to HCP. Copy of standard job description of employer. Incident report (route etc). Source patient identify and HBV/HIV status. Employer’s HBV status and other relevant medical information. HCP evaluates exposure incident. Arrange for testing as exposed employer and source patient Notifies employer of results of all testing. Provides counseling. Provides pest exposure prophylaxis of indicated. Evaluates reported illness. Sends the HCP;s written openion to employer Receives HCP’s written openion Provides copy of HCP’s written openion to employer
  46. 46. Infection control needs in dental treatment facilities require the use of disinfectants in several forms. 1) Surface disinfectants. 2) Immersion sterilants. 3) Immersion disinfectants. 4) Hand antimicrobials. Surface disinfection : It is the treatment of environmental surface such as cabinets, brackets, tables, chairs, units, heights, x-ray and similar surfaces where items are too large too sensitive to be immersed in disinfecting chemicals. Usually accomplished by spraying or wiping the solution on the surface and allowing it to remain moist and undisturbed for the manufacturer’s directed time. Immersion disinfection : Sometimes called instrument disinfection an incorrectly also called cold sterilization is the immersion of instruments, plastics and other smaller items in a liquid disinfectant contained in a disinfecting tray, historically called cold sterilizing tray. Immersion sterilization : Is the use of an EPA registered agent that has the capability of killing the liming micro-organisms and infection agents usually in 6-10 hours, immersed in solution. Hand antimicrobials : Treatment is the specific art of washing or otherwise treating hands with a chemical soap or lotion with resulting reduction in number of hand microbes. It is important to recognize that the effectiveness of both immersion and surface disinfectants is dependent on a member of factors. 1) Concentration and type of micro-organisms.
  47. 47. 2) Concentration of chemical. 3) Length of exposure time. 4) Amount of accumulated debris. CLASSIFICATION OR DISINFECTANTS: Spaulding in 1992 proposed a classification of chemical disinfectants. A) High level : High level disinfectants inactivate spands and all forms of bacteria, funci and viruses. Applied at different time schedules. High level chemical is either a disinfectant an sterilant. Eg : Ethyl oxide gas. Immersion gluteraldehyde solution. B) Intermediate level : Inactivate all forms of micro-organisms but do not destroy spares. Eg : formaldehyde, chlorine compounds, idophar, alcohol, chlorine compounds. C) Low level : Inactivate vegetative bacteria and certain lipid – type viruses but do not destroy spares, tubercle bacilli or nonlipid viruses. PROPERTIES OF IDEAL DISINFECTANT : 1) Broad spectrum : Should always have widest possible antimicrobia spectrum. 2) Fast acting : Should always have rapidly lethal action on all vegetative forms and spares of bacteria, fungi, protozoa and virus 3) Not affected by physical factors : Active in presence of organic matter, such as blood, sputum and feces. Should be compatible with soaps, detergents and other chemicals encountered in use.
  48. 48. 4) Non toxic 5) Surface compatibility. Should not carrode instruments and other metallic surfaces. 6) Residual effect on treated surfaces 7) Easy to use 8) Odorless 9) Economical Principles of action : 1) Disinfection as achieved by coagulation, precipitation or oxidation as protein of microbial alls or dematuration of enzymes of the cells. 2) Disinfection depends on contact of the solution at the known effective concentration for the optimum period of time. 3) Items must be thoroughly cleaned and dried because action of the agent is altered by foreign matter and dilution. 4) A solution has specific shelf like, use life and sense life. 1) Alcohol : Effective skin antiseptics and valuable disinfectants for medical instruments. - Ethylalcohol and isopropylalcohol are most commonly used. - Isopropylalcohol is preferred over ethylatcohol as it is a better fat solvent, more bactericidal and less volatile. - It is active against vegetative bacterial cells including the tubercle bacillus. - It denatures proteins and lipids and leads to cell membrane disintegration. - It is used to disinfect skin prior to cutaneous injections. - It is active against gram +ve, gram –ve and acid fast organism at a concentration of 50 – 70%.
  49. 49. - Isopropyl alcohol have high bactericidal activity at a concentration of 99%. - Water solution work best. 1) Alcohols work best at 60 to 95% solution with water. 2) Some water must e present for alcohol to disinfect because they act by coagulating proteins and water is needed for coagulation reaction. Also 70% alcohol-water mixture penetrates more deeply than pure alcohol into most materials. Disadvantages : - Relatively ineffective in presence of blood and saliva. - Lacks sparicidal activity. - Cause corrosion of metals. ALOEHYDES : FORMALDENYDE : - Active against amino group in the protein molecule. - Used to preserve anatomical specimen. - 10% formalin containing 0.5% sodium tetrabarate as used to sterilize clean metal instrument. - In aqueous solution it is markedly bactericidal and sparicidal and also has a lethal effect on nerves. Formaldehyde gas : - Used for sterilizing instrument and heat sensitive catheters. - Used for fumigating wards and laboratories. - Gas is resistant and toxic when inhaled. - Widely employed for fumigation of operation theaters. - After sealing windows and other outlets, formaldehyde gas is generated by adding 150 gm of (KMnOn) potassium magnesium oxide to 280 ml of formalin. Ciluteraldehyde :
  50. 50. Three types of gluteuraldehyde preparation are there alkaline, acidic and neutral preparations. Action : They are high level of disinfectant and act to kill microorganism by damaging their protein and nucleic acid by acting in aminogroup in protein molecules. Specially effective against tubercle bacilli, fungi and viruses. - Used to sterilize rubber anesthesia tubes, face mask, plastic, metal instruments, some impressions. LIMITATIONS : 1) Caustic to skin. 2) Irritating to eyes. 3) Corrosion to some metal instruments . 4) Items must be rinsed in sterile water after removal from immersion bath. IODOPHORS : Action : Iodine is released slowly from the iodophas and bring a disinfecting action as a broad spectrum antimicrobial with enhancement of bactericidal activity. Povidine – iodine preparation are widely used in the farms of surgical scrub, liquid soaps, mouth and surface antiseptics prior to hypodermic injection. - It was found that free iodine (I2) contributes to the bactericidal activity of iodophares and dilutions of iodophars demonstrate more rapid bactericidal action than does povidon – iodine solution. PHENOLS AND THEIR DERIVATIVES (CARBOLIC ACID) : - Following its introduction in 1865 by listes as a surgical antiseptic, phenol was widely used as a disinfectant. - Since mast phenolic compounds have low solubility in water, they are formulated with emulsifying agents duck as soap which increase their antimicrobial action.
  51. 51. Action : - They are cytoplasmic parsons by penetrating and disrupting all wall thereby backing to dematuration of intracellular proteins. - Phenol disinfectant are active against gram +ve bacteria. - Bacterial at 1% and fungicidal at 1.3%. LIMITATIONS : - Activity reduced in presence of organic matter. - Caustic to skin. - Expensive. Dyes : Two groups of dyes. A) Aniline dyes B) A cridine dyes. - Extensively sued as skin and wound antiseptic. - Both are bacteriastatic in dilution but have low bactericidal activity. AWLINE DYES : - Active against gram +ve than gram –ve. Action : Lethal effect on bacteria are believed to be due to their reaction with acid groups in the cells. ACRIDINE DYES : - Active against gram +ve than gram –ve. Advantages : It is impregnated in gauge, they are slowly released in moist environment and hence there advantages and use in clinical medicine. Action : They impair DNA complex of organisms and thus kill or destroy the reproduction capacity of cell. HALOGENS : 1) Iodine is apparent and has been used as a skin disinfectant active bactericidal agent with moderate activity against spars. Also active against tubercle bacilli and number of viruses.
  52. 52. 2) Chlorine compounds Action : Microorganisms are destroyed primarily by oxidation of microsomal enzymes and all membrane components. a) Chlorine dioxide : - Use life is only 1 day. - Preparation is economical and generally nontoxic. - Corrosive to metals. - Requires proper ventilation. - Irritating to eyes and skin. b) Sodium hydrochlorite : - Daily fresh solution is needed s sodium hypochlorite tends to be unstable. - Use distilled water for mixing to improve the stability. - Economical. Disadvantage : - Can harm eye, skin and clothing. - Can corrode instruments. - Skin odor may be offensive. Commonly used antiseptics and disinfectants : 1) Betadine : - Povidine iodine microbicidal solution. (0.5% w/v available iodine) - Degerming of skin pre and post operatively for surgical procedures. - Rapid and prolonged germicidal action against a wide spectrum of pathogenic organism. - Also active against bacterial spares. - In presence of blood, serum, purulent and nectrotic tissue. Its activity persist as long as the color remains. 2) Snrgi scrub :
  53. 53. Chlorhexidene gluconate 20% w/v. 3) Sterillium Hand disinfectant. Alcohol preparation. 4) Bacillo-x 25 : - Surface disinfectant. - Alcohol preparation. - Effective against bacteria veins and fungi. STERILIZATION : - Defined as a process by which an article surface or medium is freed from all microorganisms both in vegetative and spare forms (Ananathnaryan) - Process by which all forms of life including bacterial spars are destroyed by physical and chemical means (Wilkins). FLOWCHART SNOWING THE STEPS INVOLVED IN INSTRUMENT STERILIZATION : Instrument cleaning (thermal disinfection or ultrasonic) Rinse and dry Package Seal Sterilize Stare packages Clinical use
  54. 54. PREPARATION FOR STERILIZATION : Instruments and equipments intended for sterilization / disinfection procedure must be carefully prepared. The basic steps in recirculation of instruments from the time an appointment procedure is completed until the instruments are sterilized and ready for use in the next clinical appointments canes under following tuacheins. 1) Holding / pre soaking step. 2) Cleaning step. 3) Packing step. HOLDING / PRE SOAKING STEP : Cleaning is more difficult when saliva and blood are left on instrument for a period of time after use. If a cleaning process can not be accomplished immediately, a container with a holding solution of mild disinfectant or detergent should be available in which to place the used instruments. The instruments can be placed directly into the basket for later submergence into the ultrasonic cleanser. The basket can be placed in the soaking solution. CLEANING STEP : Ideally the instruments are contained within a cassette so that little or no handling is required when instruments are not in a cassette, transfer forcep are used for transferring contaminated instruments. For all cleaning processes heavy duty, puncture resistant gloves must be used and a face mask and protective eye wear must be warm. Two methods for cleaning instruments are :
  55. 55. 1) Ultrasonic cleaning. 2) Manual cleaning. MANUAL CLEANING : Ultrasonic processing is a method of choice but when manual cleaning is the only alternative, precautions must be taken to prevent contamination. PROCEDURE : 1) Wear heavy duty gloves and mask. 2) Dismantle instruments with detachable parts, open joint instruments. 3) Use detergents and scrub with a long handled brush under running water. Hold the instrument low in the sink. 4) Brush with strokes away from the body. Care should be taken not to splash and contaminate the surrounding area. 5) Rinse thoroughly. 6) Dry on paper towels. ULTRASONIC CLEANING : Ultrasonic cleaning prior to sterilization is safer than manual cleaning. Manual cleaning of instruments is dangerous, difficult and time- consuming procedure ultrasonic processing is not a substitute for sterilization. it is only a cleaning process. ADVANTAGES : 1) Increased efficiency in obtaining high degree of cleanliness. 2) Reduced danger to clinician from direct contact with potentially pathogenic microorganisms. 3) Improved effectiveness for disinfection. 4) Elimination of possible dissemination of microorganisms through release of aerosols and droplets which can occur during scrubbing process.
  56. 56. 5) Penetration into areas of instruments where the bristles of brush may be unable to contact. 6) Removal of tarnish. PRINCIPLE OF WORKING : The ultrasonic cleaning device works by producing sound waves beyond the range of human hearing. These sound waves which can travel through metal and glass containers cause cavitation (formation of bubbles in liquid). The bubbles which are too small to be seen, burst by implosion (bursting inward). The mechanical cleaning action of the bursting bubbles combined with the chemical action of the ultrasonic solution removes the debris from the instruments. PROCEDURE : 1) Guard against overloading. The solution must contact all surfaces. Instruments must be completely immersed. 2) Dismantle instruments. Open jointed instruments. 3) Time accurated by manufacturer’s guide. Usually 5 to 15 min. 4) Drain, rinse sense and air dry. PACKAGING STEP : I) PURPOSES : 1) To prevent contamination of newly sterilized instruments as soon as they are removed from the sterilizer. 2) To provide a means of staring instruments to keep then in sets for individual appointment use and sterilized and ready for immediate use on opening. II) INSTRUMENT ARRANGEMENT : 1) Preset cassettes, trays or packages can be preplanned to contain all the items usually needed for particular appointment. 2) Each package or tray should be dated and marked for identification of contents.
  57. 57. 3) Clear packages with self seal permit instrument identification without special labeling. III) PREPARATION : Each method of sterilization has specific requirements and manufacturer s recommendations must be reviewed. Wrapping is necessary to prevent punctures or tears that break the chain of asepsis and require the repeat of the process. The wrap must permit the steam or chemical vapour to pass through the content. METHOD OF STERILIZATION : - Physical method - Chemical method Physical method : 1) Sunlight 2) Drying 3) Heat 4) Filtration 5) Radiation 6) Ultrasonic and sonic vibration. 1) HEAT : A) Dry heat : 1) Flamming. 2) Red heat 3) Incineration 4) Hot air oven B) Moist heat : 1) Below 1000 C – pasteurization. 2) At 1000 C – boiling. 3) Above 1000 C – Autoclave.
  58. 58. 2) FILTERATION A) Candle filths : a) Chamber land and doulton filter – made of unglazed ceramic which after use can be cleaned with sodium hypochlorite. b) Diatomous earth filter eg – berkefold and mandler filters. c) Asbestos filters – disposable, single use eg : Seitz and sterimat filters. B) Sintered glass filters : C) Membrane filters – Made of cellulose ester. Average pare diameter is 0.22 µm. Most widely used for sterilization. Used in water purification. 3) RADIATION : 1) Ionising. 2) Nonionising 1) SUNLIGHT : - Processes appreciable bactericidal activity. - Action is mainly due to content of ultraviolet rays most of which are screened out by glass and the presence of ozone in the outer regions of atmosphere. - Natural method of sterilization. - Semple and Cirieg showed that typhoid bacilli exposed to sun were killed in two hours whereas controls kept to dark were still alive for six days. Drying : Moisture is essential for growth of bacteria. 4/5th of the weight of bacterial cells is water. Drying in air has therefore deleterious effect on many bacteria.
  59. 59. Heat : Moist heat is mast reliable method of sterilization and should be the method of choice unless contraindicated. Materials damageable by heat can be sterilized at lower temperature for longer period by repeated cycles. Factors influencing sterilization by heat are : 1) Nature of heat whether dry heat or moist heat. 2) Temperature and time. 3) Number of microorganisms present. 4) Character of the organism such as species, strain and sparing capacity. 5) Type of material from which the microorganism have to be eradicated. DRY HEAT : Action : Action or dry heat is by oxidation. Due to oxidative damage there will be protein dematuration and toxic effect of elevated levels of electrolytes. Uses : 1) Primarily for materials that cannot be safely sterilized with steam under pressure. 2) For oils and powders when they are thermostablize at the required temperature. 3) Small metal instruments that might be corroded or rusted by moisture. METHOD USED IN DRY HEAT : 1) Flamming : Inoculating loops or wires, tip of forceps and scaring spatulas are held in bunsen till they become red hot. If the loop contains infected protainaceons materials they should be first dipped in chemical disinfectant before flamming to prevent spattering. Scalpels, needles, glass shies can be sterilized by this method.
  60. 60. 2) Incineration : Excellent method for safely destroying materials such as contaminated cloth, and pathological materials. 3) Hot air oven : Conventional dry heat oven : - Mast widely used method of sterilization by dry heat. - Holding period of 1600 C for 1 hour. - Timing must start after the desired temperature has been reached. - Used to sterilize glass ware, forceps, scissors, scalpel, all glass syringes and petridishes. Mechanism : - Oven is usually heated by electricity with heating elements in the walls of the chamber. It must be fitted with a fan to ensure distribution of air and elimination of air pockets. The material should be arranged in a manner which allows free circulation of air between the objects. After sterilization the oven must be allowed to cool slowly for about 2 hours before the door is opened. Since glassware may get baked by sudden or uneven cooling. Control : Paper strips of nonroxigenic strain of clostridium ketani are used. After sterilization they are cultured in a suitable media and checked. Bacillus subtitles strips can also be used. SHORT CYCLE – HIGH TEMPERATURE DRY HEAT OVEN : A rapid high temperature process that reduces total sterilization time to 6 minutes for unwrapped and 12 minutes for wrapped instruments. They operate at 180 – 1900 C. Time and temperature recommended by medical research council. 1600 C – 45 min 1700 C – 18 min 1800 C – 7.5 min
  61. 61. 1900 C – 1.5 min Advantages : - Carbon steel instruments and burs do not rust. - When maintained at correct temperature. It is well suited for sharp instruments. Disadvantages : - High temperature many damage heat sensitive items such as rubber, plastic. Intense dry heat : Chair side sterilization of endo files can be accomplished by using glass bead or hot salt sterilizer. HOT SALT STERILIZER : It consist essentially of a metal cup in which table salt is kept at a temperature between 4250 F and 4750 F. Root canal instruments such as broaches, files, reamers sterilized in 5 seconds. Absorbent points and cotton pellets in 10 seconds. Advantage : - Use of ordinary table salt. - Salt is readily available and contains 1% sodium aluminate, magnesium carbonate and sodium carbonate that class not fuse under heat. - Pure salt should never be used. - Salt carried to root canal can be irrigated. Hot salt sterilizer has superceded the molten metal and glass bead sterilizer becomes the metal or small glass beads can clung to a wet instrument which gets clogged in the root canal.
  62. 62. GLASS BEAD : - Bead less than 1 mm in diameter. Larger beads are not effective in transferring heat. - Large air space between the beads reduce the efficiency of sterilizer. - Hottest part in salt sterilizer is along the outer rim starting at the bottom layer. Temperature is lowest in the center of surface layer. - Immerse instrument properly quarter inch below the salt surface and in peripheral area. MOIST HEAT : - Lethal effect of moist heat is due to dematuration and coagulation of proteins. - Temperature below 1000 C. Eg: Pasteurization of milk Temperature employed – 630 C for 30 minutes – holder method 720 C for 15-20 seconds – Flash method followed by coaling quickly to 130 C or lower. Temperature at 1000 C : Boiling : Vegetative bacteria are killed almost immediately at 900 C to 1000 C. - Boiling is not recommended for sterilization of instruments used for surgical procedures and regarded only as a means of disinfection. - Nothing short of autoclaving at high pressure can destroy spores and ensures sterilization. - Hard water should not be used. Sterilization can be promoted by addition of 2% sodium bicarbonate to water.
  63. 63. - In case where boiling is considered, adequate material should be immersed in water and boiled for 10-30 min. - The sterilizer should not be open during this period. AUTOCLAVE (STEAM PRESSURE STERILIZATION) : The principle of autoclave is that water boils when its vapour pressure equals that of surrounding atmosphere. Hence when pressure inside a closed vessel increases, the temperature at which water boils also increases. Saturated steam has high penetrating power. When steam comes in contact with a cooler surface, it condenses to water and fives up its latent heat to that surface. The condensed water ensure moist conditions for killing the microbes present. Hence sterilization is achieved by action of heat and moisture serves only to attain high temperature. Time, temperature and pressure recommendation : - 1210 C for 15min at 15 lbs pressure. - 1340 C for 7 min and 30 lbs pressure for wrapped instruments. STERILIZATION OF BURS IN AUTOCLAVE : For autoclave sterilization, burs can be protected by keeping them submerged in a small amount of 2% sodium nitrate solution (20 gm of sodium nitrile in 1 litre of distilled water). Then burs are placed in glass beaker with perforated lid and fill the breaker with sufficient nitrite solution approximately 1 cm above the burs. Place container of burs and fluid into sterilize and operate a normal sterilization cycle. Advantages : - Mast rapid and effective method for sterilizing cloth surgical packs an towel packs. - Does not destroy cooton and cloth products. - Excellent penetration of packages. - Sterilization verifiable.
  64. 64. Disadvantages : - Unsuitable for oils or powders that are impreviors to heal. - Items sensitive to the elevated temperature can not be autoclave. - Autoclaving tends to rust carbon steel instruments and burs. - Steam appears to corrode the steel neck / shank portions of the diamond instruments and carbide burs. Sterilization control  species of bacillus sterother –mophilus killed in 12 minutes at 550 C – 600 C and spare at 1210 C. Care of autoclave : 1) Daily – Maintain proper level of distilled water. 2) Weekly – flush the chamber with appropriate cleaning solution such as hot trisodium phosphate. PRINCIPLES OF ACTION : A. Sterilization is achieved by action of heat and moisture, pressure serves only to obtain high temperature. B. Sterilization depends on penetrating ability of steam. 1) Air must be excluded, otherwise steam penetration and heat transfer are prevented. 2) Space between the object is essential to ensure access for the steam. 3) Materials must be thoroughly cleaned and air dried, Adherent material can provide a barriers to the steam. OPERATION : A) Packing autoclave : Pack loosely to permit steam to reach all instruments in all packages. B) Temperature must remain at 1210 C at 15 pounds for 15 minutes. Use 30 minutes for heavy leads to ensure penetration. C) Cooling : 1) Dry materials : Release steam pressure, turn operating valve, and open the door. Required time for drying is about 15 minutes.
  65. 65. 2) Liquids : Reduce chamber slowly at an even rate over 10 to 12 minutes to prevent boiling as escape of fluids into the chamber. It is preferable to turn off the autoclave and let the pressure fall before opening door. CHEMICLAVE (CHEMICAL VAPOUR STERILIZER) : Hallen Back and Harvey in 1940 culminated in development of an unsaturated chemical vapour sterilization system called “HARVEY CHEMICLAVE”. PRINCIPLE : Chemical vapour sterilization kill micro-organism by destroying vital protein systems. Microbial and viral destruction results from the permeation of the heated formaldehyde and alcohol. Heavy tightly wrapped, or scaled packages would not permit the penetration of the vapours. A combination of alcohols, formaldehyde, ketone water and acetone heated under pressure produces a gas that is effective as a sterilizing agent. USE : Chemical vapour sterilization can not be used for materials or objects that can be altered by the chemicals that make the vapour as that cannot withstand the high temperature. Eg: low melting plastics, liquids, heat sensitive handpiece. TEMPERATURE : From 1270 C to 1320 C with 20 to 40 pounds pressure in accord with manufacturer’s direction. Time : Minimum of 20 minutes after correct temperature and pressure have been attained.
  66. 66. Cooling at the completion of cycle : Instruments are dry instruments need a short period for cooling. Care of sterilizer : Depending on the amount of use, refilling is needed by at least every 30 cycles. Advantages : - Corrosion and rust free instruments for carbon steel instruments. - Ability to sterilize in a relatively short total cycle. - Ease of operation and care of equipment. Disadvantages : - Adequate ventilation is needed, cannot use in small room. - Slight odor which is rarely objectionable. Control : Bacillus sterothermophilus strips. ETHYLENE OXIDE : Gaseous sterilization using ethyl oxide is not commonly found in private dental office or clinic. USE : All materials, whether metal, plastic, rubber or cloth can be sterilized on ethylene oxide with little on no damage to the material. Principles of action : Ethylene oxide vapour is affective against all types and farms of microorganisms provided sufficient – time is allowed. Operation : - Operation is well ventilated room is necessary. - Overnight processing is usually mast practical. Time and temperature : Vary from 10 to 16 hours, depending on both the temperature and the concentration of ethylene oxide used. Aeration after completion of the cycle :
  67. 67. Plastic and rubber products need to be aerated for atleast 24 hours. Metal instruments are ready for immediate use. Advantages : - Many types of materials can be sterilized with minimum or no damage to the material itself. (including plastic and rubber items) - Low temperature for operation. Disadvantages : - High cast of the equipment. - Problems of dispersement of gaseous exhaust. - Increased time of operation. - Gas absorption requires airing of plastic, rubber, and cloth goods for several hours. Sterilization control : Bacillus subtitles strips. MICROWAVE : - Microwave have wavelength longer than U.V light. - In microwave oven, waves are absorbed by water molecules. - The molecules are set into high speed motion and the heat of friction is transmitted to food which become hot rapidly. LASER : - Adam stop Hotz in 1993 showed the bactericidal effect due to laser radiation in 4-8 seconds. - Hooks et al found that infected instruments for 3 seconds to laser beam is sufficient to destroy micro-organism including spares. FREEZING : - Freezing can both kill and pressure depending on various factors. - Repeated freezing and thawing are much more destructive to bacteria there prolonged storage at freezing temperature.
  68. 68. - If bacteria are rapidly subjected to temperature below – 350 C, ice crystals that form within the cell produce a lethal effect during freezing. RADIATION : Two types of radiations used Non ionizing – infra red and ultraviolet rays. Ionizing – gamma rays and high energy systems. Non-ionizing radiation : 1) Infra red radiations is used for rapid mass sterilization of syringes. 2) Ultraviolet radiation – used for disinfecting enclosed areas such as hospital wards, operation theaters, small virus inoculation rooms and virus laboratory. Ionizing radiations : X-ray, gamma rays and cosmic rays are highly lethal to DNA and other vital all instrument as they have very high penetration power. Gamma radiation is used for sterilization of mast plastic, syringes, swab, catheters. NEW DISINFECTION AND STERILIZATION METHODS : Disinfection : Antimicrobial coating (Surfacine) Super oxidized water (Sterilox). Sterilization : Liquid sterilization – endodonts. New plasma sterilizer – Sterrad 50. STERILIZATION OF CONSERVATIVE INSTRUMENTS : Steam autoclave Dry heat Chemical vapor Ethylene oxide Chemical disinfection 1) Burs - Carbon steel. - ++ ++ ++ - - Steel + ++ ++ ++ + - Tungsten carticle + ++ ++ ++ + 2) Condensers ++ ++ ++ ++ + 3) Dapen dishes ++ + + ++ +
  69. 69. 4) Glass slab ++ ++ ++ ++ + 5) Hand instruments - Carbon steel - ++ ++ ++ + - Stainless steel ++ ++ ++ ++ - 6) Morrars - ++ ++ ++ + 7) Orthodontic phichs ++ ++ +++ ++ + 8) Pluggers ++ ++ ++ ++ + 9) Rubber dam Equipment - Carbon steel clamps - ++ ++ ++ - - Metal frances ++ ++ ++ ++ + - Plastic frances - - - ++ + - Punches - ++ ++ ++ + - Stainless steel ++ ++ ++ ++ + 10) Rubber items prophylaxis cups - - - ++ - Sterilization of endodontic instruments : 1) Broaches, files, reamers, absorber points  not salt / glass bead sterilizer. 2) Gutta-percha  screw copped vials containing alcohol. - 5.2% NaOCl – 1min rinse with water. 3) Silver cones – Bunsen flam – 3.4 min slowly Hot salt sterilizer – 5 seconds Impression materials : Autoclave Dry heat Chemical vapor Ethylene oxide Chemical disinfection 1) Impression trays - Aluminum metal ++ + ++ ++ - - Plastic - - - ++ + Saliva ejectors : High melting plastic – Autoclave, ethylene oxide. Ultrasonic scaling tips – Ethylene oxide. Impression :
  70. 70. 1) Alginate – chlorine compounds. 2) Polysulfide rubber base – Glutaraldehyde, iodophar, chlorine compound. 3) Silicone – Glutaraldehyde, iodophar, chlorine compound. 4) Polyethylene – Only chlorine compound. 5) ZnOE pass – Glutaraldehyde, Iodopharesis. Prosthesis – Glutaraldehyde. HAND PIECE STERILIZATION : - Handpiece should be flushed for 30 seconds at the beginning of dry and between every appointment. - Steam sterilization of handpieces. o Autoclave sterilization of hanpieces is are of the most rapid methods. Other methods : 1) Chemical vapour pressure sterilization – indicated for handpieces with ceramic bearing. 2) Ethylene oxide gas is gentle method of handpiece sterilization. 3) Dry heat sterilization of handpiece is hot recommended. X-ray unit asepsis : - Placing barriers on the portions of the one and tube head handled during positioning and an exposure switch. - Bite blocks used for film placement should also be sterilized between patient. DENTAL WATER LINE CONTAMINATION : Dental handpiece, water syringes, sonic / ultrasonic handpiece can be contaminated after sterilization but before patient use by biofilm contaminated dental unit water lines. Usual source is contaminated commercial water supply entering dental office. The result of biofilm contamination it that the water emitted
  71. 71. from handpieces, syringes etc. may contain elevated concentration of pseudomonas, mycobacterial, legionella. ADA recommendations to improve dental unit water quality : 1) Discharge water lines without hanpieces attached for several minutes at beginning of each dry. 2) Handpieces should run to discharge water and air for a minimum of 20-30 seconds after each patient. 3) Use filters. 4) Use sterile saliva / water as coolants. Eg: povidone – iodine 10% coupled. WASTE DISPOSAL MANAGEMENT : Type Examples Handling requirements 1) General waste Paper towels, paper mixing pads, empty food container Discard in covered containers made of durable materials such as plastic or metal 2) Hazardons waste Waste presenting a danger to humans as the environment (toxic chemicals) Follow you specific static and local regulations 3) Contaminate waste Waste that has contact with blood as other body fluids (used barriers, patient napkins) In mast states, disposed of with the general waste 4) Infections or regulated waste (biohazard) Waste that is capable of transmitting an infections disease Follow your specific state and local regulations a) Blood and blood soaked materials Blood or saliva that can be squeezed out, as dried blood that many flake off on items Containers for all three types of infections materials must be labeled with the biohazard label. b) Pathologic waste Soft tissue and extracted teeth c) Sharps Contaminated needles, Closable leak proas
  72. 72. scalpel blades, orthodontic wires, endodontic instruments (reamers and files) puncture resistant containers. Containers should be color code red and marked with biohazard symbol.

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