Chronic Obstructive Pulmonary Disease – This occurs when bacteria from the oral cavity and sinuses are able to pass down the trachea and start an infection in the upper part of the lungs. Normally the ciliated columnar epithelium of the trachea prevent this from happening. COPD is most common in older, often bedridden patients who are in poor general health and whose oral hygiene has been neglected. This is very similar to pneumonia except in COPD the fact that the bronchioles become inflamed and almost close is an additional problem.
Pneumonia – This may be due to oral microorganisms which get to the lungs directly through the trachea or the bacteria may have started as an embolism anywhere in the body. Embolisms are generally screened out of the blood by the capillaries of the lungs.
Lung cancers – The most common cause of lung cancer is the mechanism where carcinogens are breathed directly into the lungs through smoking or just being in a place with carcinogens in the air. The second largest cause of lung cancer is secondary cancer through metastasis from a primary cancer elsewhere. These cancers are caught in the capillaries of the lungs just as embolisms are screened out causing pneumonia. There is a possibility that oral infections can lead to lung cancer either through direct infection as in pneumonia or if an embolism caused by an oral infection gets screened out in the lungs. If the microorganisms in either of these infections can produce carcinogens; then a lung cancer can result.