Bloodborne viruses such as hepatitis B virus (HBV), hepatitis
C virus (HCV), and human immunodeficiency virus (HIV) are
of concern to dental health care professionals (DHCP). These
- Can be transmitted to patients and DHCP in healthcare
- Can produce chronic infection.
- Are often carried by persons unaware of their infection.
Transmission of bloodborne pathogens may occur
from patient to DHCP, from DHCP to patient, and from patient
to patient. Because DHCP frequently are exposed to blood and
blood-contaminated saliva during dental procedures, they are
at greater risk of infection by a bloodborne pathogen than
The risk of infection
with a bloodborne virus is largely determined by:
- Its prevalence, or frequency, in the patient population.
- The risk of transmission after an exposure to blood (risk
varies by type of virus).
- The type and frequency of blood contacts.If health care
personnel are frequently exposed to blood, especially if
they are working with sharp objects such as needles, their
risk of exposure to a bloodborne virus is higher than if
they rarely come into contact with blood.
Characteristics of Percutaneous
Injuries Among DHCP
According to the CDC (2003), available information indicates
that percutaneous injuries among dentists declined from an
average rate of 11 injuries per year in 1987 to <3 injuries
per year in 1993.
In general, most injuries among general dentists were caused
by burs, followed by syringe needles and other sharp instruments.
Injuries most often occur while the dentist's hands are outside
the patient's mouth. Most injuries involve small, rather than
large, amounts of blood.
The frequency of percutaneous injuries among oral surgeons
is similar to that reported among U.S. dentists. Injuries
among oral surgeons may occur more frequently during procedures
using surgical wire, such as during fracture reductions.
of Bloodborne Virus Transmission after Needlestick (CDC,
HBsAg+ and HBeAg+
HBsAg+ and HBeAg
- 22.0%-31.0% clinical hepatitis; 37%-62% serological
evidence of HBV infection.
1.0%-6.0% clinical hepatitis; 23%-37% serological evidence
of HBV infection
||1.8% (0%-7% range)
||0.3% (0.2%-0.5% range)
The average risk of transmission after a single needlestick
from an infected patient by type of bloodborne virus varies
greatly by type of virus.
For instance, the risk of HBV transmission after a percutaneous
exposure (e.g., needlestick) to HBV-infected blood varies
from 1%-62%, depending on the hepatitis B e-antigen (HBeAg)
status of the source patient. If the source patient's blood
is positive for HBeAg (a marker of increased infectivity),
the risk of transmission can be as high as 62%. If the patient's
blood is hepatitis B surface antigen (HBsAg) positive but
HBeAg negative, the risk varies from 1%-37%.
The average risk of HCV transmission after a percutaneous
exposure to HCV-infected blood is 1.8%.
The average risk of HIV infection after a percutaneous exposure
to HIV-infected blood is 0.3%. To put this in perspective,
1 in 3 needlesticks from an HBeAg+ source patient would result
in infection compared to only 1 in 300 needlesticks from an
As mentioned earlier, one factor to consider
in assessing the risk of infection is the type of body substances
to which DHCP are exposed. This slide shows the concentration
of HBV in various body fluids. On the left, in red, are the
fluids with the highest concentration of virus.
Moving from the left to the right side, the
concentration decreases. Blood, for instance, has a higher
virus concentration than urine or sweat. Saliva alone, without
blood, has a moderate concentration of virus.
Transmission of bloodborne pathogens (e.g.,
HBV, HCV, and HIV) in dental health care settings is rare,
any incidence of exposure can have serious consequences. Exposure
to infected blood can result in transmission from patient
to dental professional and from dental professional to patient,
and from one patient to another. The opportunity for transmission
is greatest from patient to dental professionals, who frequently
encounter patient blood and blood-contaminated saliva during
No transmission of HIV from dental professionals
to patient has been reported since 1992 (CDC, 2003). The last
HBV transmission from dental professional to patients was
reported in 1987. No transmission of HCV from dental professional
to patient has been reported.
The majority of dental professionals infected
with a bloodborne virus do not pose a risk to patients because
they do not perform activities meeting the necessary conditions
for transmission. For dental professionals to pose a risk
for bloodborne virus transmission to patients, the dental
professional must (CDC, 2003):
- Be viremic (i.e., have infectious virus circulating in
- Be injured or have a condition (e.g., weeping dermatitis)
that allows direct exposure to their blood or other infectious
body fluids; and
- Enable their blood or infectious body fluid to gain direct
access to a patient's wound, traumatized tissue, mucous
membranes, or similar portal of entry.
Although an infected dental professional might
be viremic, unless the second and third conditions are also
met, transmission cannot occur.
The risk of occupational exposure to bloodborne
viruses by the dental professional, from patients, is largely
determined by the viral prevalence in the patient population
and the nature and frequency of contact with blood and body
fluids through percutaneous or permucosal routes of exposure
(CDC, 2003). The risk of infection after exposure to a bloodborne
virus is influenced by (CDC, 2003):
- Inoculum size,
- Route of exposure, and
- Susceptibility of the exposed dental professional.
Continue on to Preventing
Transmission of Bloodborne Pathogens, Con't.