Infection Control and Office Safety Guide

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

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

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.

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

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).

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.

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:

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).

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.

• 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

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.

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.

• 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:

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.

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.

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

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.

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

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 :

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.

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

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.

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
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.
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

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

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

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

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

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.

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 :

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.

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.

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 :

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.

• 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:

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

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.

• 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.

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 :

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.

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 :

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

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

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

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.

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

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.

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.

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%.

- 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 :

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.

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.

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 :

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

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 :

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.

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.

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.

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.

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.

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

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.

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.

- 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.

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.

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.

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 :

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.

- 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 ++ + + ++ +

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 :

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

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

scalpel blades, orthodontic
wires, endodontic
instruments (reamers and
files)
puncture resistant
containers. Containers
should be color code red
and marked with biohazard
symbol.

Infection Control and Office Safety Guide

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Infection Control and Office Safety Guide