use of liquid chemical germicides depends on consideration of multiple factors including the degree of microbial killing required; the nature and composition of the surface, item or device to be treated; and the safety, cost and ease of use of the available agents.
Laboratories have become an integral part of health
care, industrial and pharmaceutical organizations. The
function of laboratories in each of these areas varies. A
laboratory could cater to diagnostic, research and quality
control procedures. As the complexities of the procedures
increase disinfection and infection control acquires a
Laboratorians working with infectious agents are subject
to laboratory acquired infections as a result of accidents,
unrecognized incidents and improper disinfection. The
degree of hazard depends upon the virulence of the
biological agent concerned and host resistance. Other
than infections contamination of work material often lead
TABLE 2.2: Spaulding classification system
Device classification Devices Spaulding process classification EPA product classification
Implants, scalpels, needles, other
Sterilization-sporicidal Chemical:
Flexible endoscopes, laryngoscopes,
similar instruments. Lab instruments
Thermometers, hydrotherapy tanks
High level disinfection-sporicidal.
Intermediate-level disinfection
Hospital disinfectant with label
claim for tuberculocidal activity
Stethoscopes, tabletops, bedpans,
Low level disinfection Hospital disinfectant without
label claim for tuberculocidal
TABLE 2.3: Modified spaulding scheme (dental)
Classification Area of use Dental instrument/item
Critical Penetrates soft tissue, contacts bone, enters into or
contacts the bloodstream or other normally sterile tissues
Surgical instruments, periodontal sealers, scalpel blades,
Semi critical Contacts mucous membrane or non-intact skin; does not
penetrate soft tissue, contact bone, enters into or contacts
the blood stream or other normally sterile tissues
Dental mouth mirror, amalgam condenser, reusable dental
impression trays, dental handpieces
Noncritical Contacts intact skin Radiograph head/cone, blood pressure cuff, facebow, pulse
false interpretation of results.
Modern medicine has undoubtedly reduced mortality
and morbidity rates with prompt diagnostic and therapeutic
measures. The blood related infectious diseases gained a
new face of terror among health care workers when reports
of the first needle stick related infections hit headlines. On
one hand as health care aims at combating existent health
perils, on the other it faces new challenges such as HIV and
Awareness camps, systematic waste segregation,
safe handling of laboratory wastes including laboratory
samples and glassware; culture of stocks of infectious
agents became important aspects of infection control. In
all these wastes, the major concern is to prevent accidental
There is growing trend in health care settings to provide
or reuse disposable materials to reduce cost factor. Such
practices could further lead to transmission of diseases
unless appropriate changes are made in the routine
Thus arises the million-dollar question; “Should one
decontaminate before disposal?” Yes, in order to ensure
complete protection to personnel handling laboratory
waste prior and post disposal it becomes necessary
to decontaminate. The United states environment
protection agency (USEPA) recommends the cleaning
and decontamination of laboratory glassware prior
to sterilization as a key step to effective and foolproof
sterilization and adequate protection.
The practice of density involves high risk of infection
by both cross contamination amongst patients and direct
transmission to the dental health care professionals.
They are often exposed to potent organisms including
Cytomegalovirus, HBV, HCV, Herpes simplex virus, HIV,
Mycobacterium spps, Staphylococcus, Streptococcus
and other viruses and bacteria that colonize or infect
the oral cavity and respiratory tract. The most frequent
routes of transmission in dental settings are (1) direct
contact with blood/oral fluids or other patient materials,
♥(2) indirect contact with contaminated objects (e.g.
instruments, equipments, environmental surfaces) (3)
contact of conjunctival, nasal/oral mucosa with droplets
(e.g. spatter), containing microorganisms generated from
an infected person and propelled at a short distance (by
coughing, sneezing or talking) (4) inhalation of airborne
microorganisms that can remain suspended in the air for
Infection control is an important element of safe dental
practice. Whilst many of the disinfection and sterilization
issues relevant to dentistry are generic and no different
from those in other areas of healthcare, dental practice
raises some particular problems. These include high
patient turnover, use of large numbers of small intricate
devices, varying degrees of invasiveness and point of use
The emergence of Human Immunodeficiency Virus
(HIV) in the early 1980s prompted a major review of
infection control procedures in dentistry.
The revised CDC emphasizes on the use of appropriate
sterilization and disinfection methods to curb infections via
contaminated instruments, although the basic Spaulding
scheme still forms the basis of the right choice and use of
disinfectants. It has been customized to meet the specific
requirements of dental health care personnel and patients
to ensure complete control of infections (Table 2.2).
The choice of specific disinfection agents is largely a
matter of judgment, guided by product label claims and
instrumentation and government regulations. A single
liquid chemical germicide might not satisfy all disinfection
requirements in a given dental practice or facility. Realistic
use of liquid chemical germicides depends on consideration
of multiple factors including the degree of microbial killing
required; the nature and composition of the surface, item or
device to be treated; and the safety, cost and ease of use of
The SI units (Système International d’Unités) have replaced
the old system of reporting and measurements. This is in
accordance with a World Health Organization resolution
which recommends the adoption of the International
System of Units by the medical community throughout the
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