How Strong is the Evidence Linking Periodontitis and Cardiovascular Disease?

The certainty that periodontal therapy can prevent cardiovascular disease in those diagnosed with chronic periodontitis is very low indeed, yet the dental community continues to tell patients just the opposite. Why are we giving patients misinformation, and how many of us have bought into a clearly misleading message? Only a handful of my colleagues agree with me on this, even though I can support my position with best evidence. It saddens me to think that dental professionals still haven’t fully embraced evidence-based decision-making.

I’ve often wondered why some healthcare professionals think objectively, like scientists, while others fall prey to biased information. Applying the principles of scientific thought begins when you study research methodology. I learned research from one of the best, the late Michele L. Darby, professor emeritus at Old Dominion University. I didn’t intentionally learn to think this way, but fortunately for me, it fell in my lap as I began graduate school. I was a teaching assistant to Professor Darby in an introductory course on dental hygiene research methods, and I had to hustle and read late into the night to grasp the often-challenging material.

Racking my brain to recall the beginning of the hype about the perio/cardio link, I think back to 2012 and an article I co-authored with a periodontist/professor on the strength of this association.¹ I remember thinking while in the throes of this massive project that my head was about to explode, mainly because I had to review and analyze the data all by myself. As many will recall, 2012 was also the year when the American Heart Association (AHA) issued a scientific statement about evidence to support an independent association between periodontal disease (PD) and atherosclerotic vascular disease (ASVD). At that time, observational studies (whose level of evidence Sanz, Marco Del Castillo, Jepsen, et al characterized as “low”) supported an association between PD and ASVD independent of known confounders, but NOT a causative relationship.² Various periodontal interventions had resulted in a reduction of systemic inflammation and endothelial dysfunction in short-term studies, but there was no evidence that the interventions prevented ASVD or modified its outcomes.²

I remember the furor among the dental community when the AHA issued this statement and the periodontal community, in particular, being disappointed with the result. In response, the European Federation of Periodontology (EFP) and the American Academy of Periodontology (AAP) decided to conduct its own review in support of independent associations between severe periodontitis and several systemic diseases. Since then, the periodontal community has been reporting on new scientific information that provides additional evidence to support these associations.²

Trying to ascertain the strength of this association is difficult because the online landscape is dominated by special interests and bias. Just like the pandemic, it’s very hard to be objective owing to the different conclusions reached by various parties. Massive disinformation during the Covid pandemic obscured the fact that the virus is spread through aerosols. If public health experts had made the message clear, everyone would have understood why good masks/respirators, ventilation, and filtration are crucial to avoiding it. People are still getting sick and dying needlessly.

Scientists are trained to avoid as much bias as possible. The Cochrane Oral Health Group is an international network that uses high-quality information help patients make health decisions.³ They publish review data (systematic reviews) in a standardized, objective, and transparent way. To provide an overview of all the evidence surrounding a question like, “Does periodontal therapy prevent cardiovascular disease in people with periodontitis?” healthcare providers should read the following.

Cochrane Review: Periodontal therapy for primary or secondary prevention of cardiovascular disease in people with periodontitis—Third update, 2022

The question of whether periodontal therapy can help prevent cardiovascular disease (CVD) in people diagnosed with chronic periodontitis is the question this third updated systematic review addresses. The first systematic review was published as a Cochrane review in 2014 and the second one was published in 2019. The objectives of the latest review (2022) were to investigate the effects of periodontal therapy for primary or secondary CVD in people with chronic periodontitis.4 Search methods included databases to identify published, unpublished, and ongoing studies up to November 17, 2021. Selection criteria included randomized controlled trials (RCTs) that compared active periodontal therapy to no periodontal treatment or a different periodontal treatment. RCTs are prospective studies (individuals are observed over a period of time), and they reduce bias and provide a rigorous tool to examine relationships between intervention and outcome. Data collection and analysis included a “risk of bias” assessment and a special Cochrane tool to assess risk of bias in the studies. GRADE criteria were used to assess the certainty of the evidence. The analysis included 3 authors, 2 of whom carried out the study identification, data extraction, and risk of bias assessment independently and duplicated each other’s work. Discrepancies were resolved by discussion with a third review author.

The main results included 2 RCTs, but the authors indicated there were no completed RCTs on this topic since the last update in 2019. Instead, they focused on 2 RCTs, one of which addressed primary prevention (onset) of CVD and the other, secondary prevention (reducing the impact of disease). Both RCTs were considered to be at high risk of bias, and both provided low-certainty evidence. The authors were unable to determine whether scaling and root planing (SRP) plus amoxicillin and metronidazole could reduce incidences of death at 1-year follow-up. For secondary prevention, the results were even more dismal. For the 303 participants who received SRP and oral hygiene instruction compared with those who received only oral hygiene instruction, cardiovascular events were measured at different time periods, ranging from 6 to 25 months. Only 37 participants were available to measure at 1-year follow-up and no conclusions were drawn. Please read the complete Cochrane report for particulars, especially the methods section of the 3 reports (2014, 2019, and 2022). The evidence to date is inconclusive and unreliable, and further trials are needed to determine whether treatment for periodontal disease can prevent the occurrence or recurrence of CVD.⁴

Even though no causal relationship has been established between periodontal therapy and CVD, research in this area opens the door for dental providers to discuss clinical trials to date but, even more important, optimal health. I’ve learned that “not being sick” and being healthy are completely different things and that, as healthcare providers, we’re not very good at teaching or guiding people to adopt healthy habits. We’re better at reacting to disease and waiting for them to get sick, and in dentistry, we sometimes overpromise and focus too much on esthetics.

When reading the literature, thinking like a scientist requires us to be objective and acknowledge our biases. Trusting the relevant experts isn’t easy because too many people claim to be experts. We should always be open to changing our minds as new information becomes available, but must recognize that medical and dental science are far from understanding all of the body’s workings. We are always waiting for science to catch up, and lifestyle changes like losing 30 pounds or walking daily can make a big difference. Because our knowledge of certain subjects may always be limited, we need to be comfortable in our own skin and explain our limitations with confidence. My patients always appreciate it when I do that, even as I offer them recommendations.

References

1. Kotsovilis S, Slim LH. Periodontal and cardiovascular diseases: statistical or causal association? A review and analysis using Hill’s criteria for causation. Can J Dent Hygiene. 2012:46(2):131-142.
2. Sanz M, Marco Del Castillo A, Jepsen S, et al. Periodontitis and cardiovascular diseases: Consensus report. J Clin Periodontol. 2020;47(3):268-288. doi:10.1111/jcpe.13189
3. What is Cochrane? Cochrane Library. Accessed February 28, 2023. https://www.cochrane.org/about-us
4. Ye Z, Cao Y, Miao C, et al. Periodontal therapy for primary or secondary prevention of cardiovascular disease in people with periodontitis. Cochrane Database Syst Rev. 2022;10(10):CD009197. doi:10.1002/14651858.CD009197.pub5