Hype vs. Evidence: Revisiting research regarding oral/systemic disease

March 13, 2015
Key West is legendary for its New Year's Eve parties, and I was lucky enough to participate (hoorah!). With a painkiller in hand (delicious rum drink), I spent the early part of the day at the beach and rummaged around my beach bag for a magazine to read.


Key West is legendary for its New Year's Eve parties, and I was lucky enough to participate (hoorah!). With a painkiller in hand (delicious rum drink), I spent the early part of the day at the beach and rummaged around my beach bag for a magazine to read.

Redbook (the January issue) featured an article called, "What dentists tell their friends." So I started reading it. I read some advice from a diplomate from the American Academy of Periodontology who was asked why a woman might not be able to conceive. Here was part of her answer: "Research shows that women who have periodontitis can take longer to conceive, and unfortunately, those who do get pregnant are at higher risk for giving birth to a preterm or low-birth-weight baby."

Along similar lines, I was posting on the ADHA LinkedIn group yesterday and was intrigued by a new discussion about "keeping oral/systemic secrets." I questioned the evidence and ended up hearing from a physician, Dr. Charles Whitney, who informed me that causation level evidence shows that oral spirochetes are one of the causes of Alzheimer's disease. He also told me that there's Level A association evidence showing that periodontal infection contributes to cardiovascular disease.


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So what did I do after reading Dr. Whitney's comments? I searched the literature and found that there isn't any causation evidence to support his first hypothesis. His comment on evidence to support more than just a link between periodontal infection and cardiovascular disease is in direct opposition to what the American Heart Association concluded in their recent scientific statement.1

So, what's going on here? Am I the only dental hygiene skeptic willing to challenge individuals who make statements that appear to be an exaggeration of evidence? Dr. Oz and other mainstream TV medical talk shows feature doctors who have been recently called out for their exaggerations of science, too. Dr. Oz, in particular, gets excited about a lot of diets. I even watched a Dr. Oz episode in which he agreed with a brain doctor named David Perlmutter (a guest promoting a new book called "Grain Brain") who recommends a special diet to keep blood sugar down to prevent Alzheimer dementia.

According to a Canadian media study published online in the British Medical Journal, patients should be skeptical about these claims and recommendations, and for good reason.2 Viewers have little basis for informed decision-making because scientific evidence is contradictory or absent and specific details on the magnitude of benefit or harm, and costs and inconvenience of recommendations, are lacking. Media study investigators wrote the following: "Approximately half of the recommendations have either no evidence or are contradicted by the best available evidence."

Sometimes, when I want further clarification on a certain topic, I turn to my peers. One, in particular, always gives me objective and impartial advice. Frieda Pickett, RDH, MS, is a retired academician who, in 2012, led a team of dental hygienists with advanced degrees to write a series of narrative reviews (including one systematic review) on various oral/systemic links. Here's what Frieda has to say about the continuing timeline of scientific discoveries concerning some of the oral/systemic links.

In 2012, you were part of a team of oral health-care professionals who published a series of articles in the Canadian Journal of Dental Hygiene on the strength of the evidence linking periodontal disease to certain systemic diseases such as atherosclerotic vascular disease (ASVD) and stroke. Has the level of evidence to support any of these links changed, and what links did your team review?

Pickett: The team we gathered were all experienced scientific writers, nuanced in the skill of critical analysis of scientific biostatistics and study design. The team agreed that use of systematic reviews, using the highest quality studies, would be the literature reviewed to determine the strength of the evidence. The entire issue of the May 2012 CJDH was devoted to discussion of the strength of the evidence on the various oral/systemic links.

Since that time, the European Federation of Periodontology held a conference in 2012 to discuss the same issues and published several systematic reviews on the same topics in 2013. They looked at essentially the same studies that were examined by authors involved in our project.

Regarding the CVD/stroke associations, the authors found not one study to prove that periodontal disease (PD) causes a non-oral disease, and not one intervention study reporting treatment of PD improved the control of either CVD or reduced stroke.

Most studies used surrogate measures to determine associations, not actual improvement outcomes from intervention trials of the disease. Only one pilot intervention study (PAVE study) has been published, and it did not report any difference in cardiac outcomes between the treatment group and the community group.

A summary of papers for CVD, adverse pregnancy outcomes, and diabetes is in July 2013 JADA "Editorial: Periodontitis. The canary in the coal mine." Regarding the relationship of PD/CVD associations, the authors write, "No intervention studies have tested any potential effect of periodontal treatment directly on preventing initial ACVD events (primary prevention) or on preventing recurrence (secondary prevention)."

A section at the end of the editorial regarding what to tell patients includes: "There still are no confirmatory studies applicable to the general population that would suggest that treatment of periodontal disease would prevent or attenuate other systemic diseases. Nonetheless, the results of some studies suggest there may be individuals with particular susceptibilities for whom elimination of periodontal disease may benefit specific disease; however, who these individuals are has yet to be determined. Chances are good that periodontal disease could be a marker of greater general health issues."

The Journal of Periodontology published papers from the European Conference in 2013. The SR (Dietrich et al.) on PD and CVD revealed, "The majority of studies failed to demonstrate an association between PD and CHD incidence in older subjects." The Dietrich SR excluded studies using surrogate measures of PD.

Please clarify the strength of the evidence surrounding the periodontal disease (PD) and adverse pregnancy outcomes (APO).

Pickett: Although early epidemiologic trials suggested an association between PD and APO, there have been five large intervention studies (which is study design to show "causation") investigating this issue. All studies found the same result, which is that traditional periodontal therapy to reduce inflammation does not reduce APO.

Furthermore, a large multicenter cohort study completed by the University of Pennsylvania found no association between PD and APO. The most recent intervention study reported those receiving periodontal treatment had a higher incidence of APO than the group that did not get treatment (difference not statistically significant).

In terms of SRs, a recent SR (which included 13 intervention trials) concluded there is no evidence that periodontal treatment improves APO. A consensus report in the 2013 Journal of Periodontology and Journal of Clinical Periodontology collection of papers presented at the European Conference found no evidence of improvement. A concluding statement reads as follows: "Although periodontal therapy has been shown to be safe and leads to improved periodontal conditions in pregnant women, case-related periodontal therapy, with or without systemic antibiotics does not reduce overall rates of pre-term birth and low birth weight."

Is it reasonable to tell a patient that treating periodontal disease will reduce total body inflammation?

Pickett: There is good evidence that during the first few weeks following periodontal therapy inflammatory chemical levels increase significantly. However, these chemicals decline by three months following therapy. In fact, one paper was written suggesting periodontal therapy might put a patient with severe CVD at risk for a cardiac event. There is no evidence to support this speculation, however, and periodontal therapy for individuals with CVD is generally considered safe. New guidelines suggest delaying noncardiac surgery (this does not include periodontal maintenance therapy) for six months following placement of stents in coronary vessels.

The guidelines from the American College of Cardiology and American Heart Association put oral surgery at a low risk for cardiac complications, and call for no noncardiac procedures in the first 30 days following a myocardial infarction. Reduction of total body inflammation is a desired outcome but it is unknown what benefits to health this provides, if any.

Perhaps a better question is, "Does periodontal treatment confer a cardiac benefit?" This has been recently addressed by an American Heart Association select committee. At the end of the report, the authors (one of whom is a periodontal educator/scientist and another is an oral medicine specialist) write: "Statements that imply a causative association between PD and specific atherosclerosis vascular disease (ASVD) events or claim that therapeutic interventions may be useful on the basis of that assumption are unwarranted." RDH


1. circ.ahajournals.org/content/early/2012/04/18/CIR.0b013e31825719f3

2. bmj.com/content/349/bmj.g7346

LYNNE SLIM, RDH, BSDH, MSDH, is an award-winning writer who has published extensively in dental/dental hygiene journals. Lynne is the CEO of Perio C Dent, a dental practice management company that specializes in the incorporation of conservative periodontal therapy into the hygiene department of dental practices. Lynne is also the owner and moderator of the Evidence-Based Dental Hygiene Group (EBDH) on LinkedIn. Evidence-based periodontal therapy will be part of the group's focus, and Lynne enjoys mentoring dental hygienists in EBDH. She can be reached at [email protected] or www.periocdent.com.