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Can
respiratory infection be linked to oral health?
The anatomic connection between the lungs
and the month makes the latter a potential reservoir of
respiratory pathogens. Micro-organisms may enter the lungs
by inhalation or by aspiration of orophaiyngeal
secretions. It seems plausible that oral micro-organisms
might infect the respiratory tract.
Only recently has the role of oral flora
in the pathogenesis of respiratory infection been examined
closely. In the literature reviewed here, at least a dozen
studies provide direct evidence of an association between
pulmonary infection and oral diseases.
Nosocomial (hospital-acquired) pneumonia
is the second most common infection in long-term care
institutions. Because anaerobes are implicated in
pneumonia, a role for the oral cavity in the pathogenesis
of this disease has been suspected since the beginning of
the 20th century. One researcher found a trend toward a
lower prevalence of pneumonia among edentulous elderly
patients and an association between xerostomia and the
development of pneumonia.
In a 2001 study, dental caries, cariogenic
bacteria and periodontal pathogens emerged as potentially
important risk factors for cases of aspiration pneumonia.
Oral flora may also be implicated in pulmonary diseases
affecting airflow. The most prevalent is chronic
obstructive pulmonary disease (COPD). Though the main
etiologic factor is tobacco use, bacteria, including oral
bacteria, may affect the progression of disease.
An analysis published in 2001 reports a
significant association between COPD and periodontal
attachment loss. The likelihood of COPD increased with the
severity of attachment loss, and lung function appeared to
diminish as the amount of attachment loss increased.
Epidemiologic findings seem to be
supported by biologic ones in that pulmonary emphysema and
periodontal disease share a similar mechanism of tissue
destruction. In both diseases, degranulation of
neutrophils occurs during attempted phagocytosis, which
releases proteolytic enzymes. Proteins from the connective
tissue are degraded, which results in destruction of the
pulmonary alveolus or the periodontal attachment.
The literature provides evidence of an
association between pulmonary infection and oral diseases.
The association seems to occur in patients with severely
compromised health, in frail elderly people and in
patients with chronic pulmonary disease.
Improving oral hygiene might reduce the
risk of pneumonia for some patients. A more rapid
intervention may be the use of oral disinfectant, but
studies on long-term use of such medications is lacking.
The treatment of periodontal diseases (either by repeated
use of antibiotics or through clinical intervention) may
reduce the incidence of pneumonia in at-risk populations.
More research, intervention studies especially, is needed.
Source: Mojon, P. Oral health and
respiratory infection. J Canad Dent Assoc 2002;
68(6):340-345.
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