Assessment of the state of the science on the association between periodontal diseases (PDs) and systemic diseases.

1) Some adverse outcomes of systemic diseases have been found to be statistically associated with periodontal diseases (PD).  The strength of this association, measured most of the time by the size of the odds ratio, varies across studies based on study design and outcome.

2) Causation has not been proven. Many researchers have moved from causation to association in their assessment of the evidence.

3) Some intervention studies addressing PDs to prevent adverse outcomes have shown effects while others not, which may support the idea of a common underlying factor: for example chronic inflammatory process. PDs, however, have not been demonstrated to cause chronic inflammatory processes elsewhere in the body.

4) At one time, there were more "reviews of the literature" than actual studies.

5) There is an ongoing Cochrane review on this subject which may shed light on the overall quality of available studies. On personal assessment, the ability of many of these studies to demonstrate association, much less causation, is lacking.  The most important issue is accounting for confounding factors strongly associated with the outcome and the exposure, e.g., tobacco exposure, nutrition.

6) There are continuing attempts to link PDs with various systemic diseases and adverse outcomes. The so-called "new periodontal paradigm" is in some regards a reiteration of the old focal infection theory of the early 1900s.

7) Periodontal health has value in itself regardless whether there is a link with systemic diseases or not. 

8) Currently, we do not have a reliable estimate of the prevalence or severity of periodontal infections in the population.

9) There is still an incomplete understanding of the pathogenesis and physiopathology of what we call periodontal infections which later express clinically as lost of attachment.

10)  It is not probable that people die directly as a consequence of not flossing.

Eugenio Beltran, DMD, MPH, MS, DrPH

Diplomate American Board of Dental Public Health

Senior Scientist

Division of Oral Health

Centers for Disease Control and Prevention