Continued professional and, of late, consumer awareness of the link between oral and systemic health has been focused largely on investigations looking at the relationship and common risk factors associated with periodontal disease and cardiovascular disease, diabetes, premature low birth weight infants, osteoporosis, and most recently, pancreatic cancer. In this article, Azarpazhooh and Leake conduct a systematic review investigating evidence for a possible etiologic association between oral health, and pneumonia and chronic obstructive pulmonary disease (COPD). Interestingly, unlike many of the other “oral-systemic” relationships which are based on changes within the immune system and systemic physiology/biochemistry, the relationship between oral health and pneumonia is more of a direct association, with the aspiration of pathogens from plaque surrounding teeth/dentures and from periodontal pockets believed to be the primary mechanism. And indeed, it has been hypothesized that the oral cavity may act as a source or reservoir for these organisms.

The first section of the systematic review looks at the association between pneumonia and oral health, analyzing the results of four prospective cohort studies and one case-control study. The second section discusses the association between periodontal disease and COPD, and reports on two case-control and two cross-sectional studies.

The last section addresses the reversibility of pneumonia, and includes ten clinical trials that examine the evidence regarding oral health interventions designed to reduce the progression or occurrence of respiratory diseases.

The authors concluded there is evidence of an association between pneumonia and oral health. This association is stronger with pneumonia than with COPD, although oral health is weakly associated with the latter. More importantly, there is good evidence that improved oral hygiene and frequent professional oral health care reduces the progression or occurrence of respiratory diseases. This is particularly true among high-risk elderly adults living in nursing homes and especially those in intensive care units.