Periodontal diseases can also lead to respiratory disease including pneumonia and acute bronchitis as well as chronic obstructive pulmonary diseases. This link between microbial infection and pneumonia results from aspiration of oral microorganisms into the respiratory tract. Pathogens are shed into the saliva and aspirated into the lung where they cause infection. Host defence mechanisms are unable to eliminate the microorganisms resulting in aspiration pneumonia. Cytokines originating from periodontal tissues may contribute to respiratory inflammation by making changes in the respiratory epithelium.
The swallowing difficulty that often accompanies elderly individuals also increases the amount of bacteria in the mouth as many suffer from oral dryness. Insufficient saliva does not effectively wash the oral debris, increasing the likelihood that oral debris will inadvertently be inhaled into the lungs. Mechanical ventilators magnify the risk for those patients who cannot breathe on their own and these patients are 20 times more likely to develop pneumonia. Oral bacteria can also grow on the inside of the ventilator tube (as it does in dental waterlines) and increase the risk of aspiration.
Health care associated (hospital acquired) pneumonia is a common cause of death in elderly patients and is caused by species that do not often colonize the oropharynx. The oral cavity has been suggested as an important reservoir for these pathogens and there is conclusive data that preventive oral care such as helping the patient cleanse the mouth reduces mortality from this type of pneumonia.
Sjogren, P.; Fesell, M.; Johansson, O.; Hoogstraate, J.: A systematic review of the preventive effect of oral hygiene on pneumonia and respiratory tract infections in elderly people in hospitals and nursing homes: effect estimates and methodological quality of randomized controlled trials. J Am Geriatr Soc. 56(11):2126-2130, 2008.