Oral Hygiene and Cancer

The link between periodontal disease and heart disease is so well documented at this point as to not need further discussion, but evidence is also accumulating, and has been for some time, of a link between cancers (of various kinds) and poor oral hygiene.


Truly strong evidence for a link between cancer and poor oral hygiene is hard to establish, of course, because of the high number of potential confounders that could render such a link spurious. For example, the number of teeth a person has is not only an indicator of lifetime oral health but socioeconomic status as well. Poor people don't spend as much time at the dentist's office as wealthier people. We know that poverty and obesity are highly correlated and that obesity carries a cancer risk. Poor people also smoke more than rich people, giving rise to more heart disease and cancer. Teasing apart all the factors that could account for any supposed link between poor oral health and cancer is difficult, at best.

Nevertheless, it is possible, with careful experimental design, to tease apart some of these factors, and scientists have gotten much better at this in recent years. Which makes the following studies (suggesting a connection between poor oral health and cancer) all the more attention-getting. How ironic would it be if a bottle of Scope and a toothbrush turned out to be the key to preventing pancreatic cancer?

In "Periodontal Disease, Tooth Loss and Cancer Risk in a Prospective Study of Male Health Professionals" (Lancet Oncol. June 2008), a prospective study of cancer in male health professionals (people who probably go to the dentist), Dominique Michaud and colleagues tracked 48,375 men over a period of 18 years. The study found:

After adjusting for known risk factors, including detailed smoking history and dietary factors, periodontal disease history was associated with an increased risk of total cancer (HR = 1.14, 95% CI = 1.07–1.22, compared with no history of periodontal disease); by cancer site, statistically significant associations were observed for lung (HR = 1.36, 95% CI = 1.15–1.60), kidney (HR = 1.49, 95% CI = 1.12–1.97), pancreatic (HR = 1.54, 95% CI = 1.16–2.04; results previously published), and hematopoietic cancers (HR = 1.30, 95% CI = 1.11–1.53). Fewer teeth at baseline (0–16) was associated with a non-significant increase in risk of total cancer (HR = 1.09, 95% CI = 0.99–1.20, compared to 25–32 teeth); a statistically significant association was observed for lung cancer (HR = 1.70, 95% CI = 1.37–2.11, for 0–16 vs. 25–32 teeth).

Michaud and her colleagues focused on pancreatic cancer, specifically, in a separately published study in the Journal of the National Cancer Institute in January 2007. The team found that a "history of periodontal disease was associated with increased pancreatic cancer risk," with a risk ratio for smokers of 1.64 and for never-smokers 2.09 (meaning that if you've never smoked, your odds of being diagnosed with pancreatic cancer more than double if you have periodontal disease).

In "An Exploration of the Periodontitis-Cancer Association" (Ann Epidemiol. May 2003), Huipel et al. examined data for 11,328 adults enrolled in NHANES and found:

Compared with individuals with a healthy periodontum, fatal cancer occurrence was positively associated with periodontitis at baseline (age and gender adjusted odds ratio = 1.55, 95% confidence interval: 1.25-1.92). Of the different cancer types, lung cancer demonstrated the strongest association. After adjustment for known risk factors for lung cancer, the magnitude of the association between periodontitis and lung cancer ranged between 1.48 (95% confidence interval: 0.88-2.50) and 1.73 (95% confidence interval: 1.01-2.97).

In "Tooth loss is associated with increased risk of total death and death from upper gastrointestinal cancer, heart disease, and stroke in a Chinese population-based cohort" (Int J Epidemiol. April 2005), Abnet et al. conducted a cohort study that included 29,584 healthy Chinese adults who were participants in a chemoprevention trial from 1986 through 1991 and who were followed up through 2001. The principal finding:

Individuals with greater than the age-specific median number of teeth lost had statistically significant 13% increased risk of total death [95% confidence interval (CI) 9–18%], 35% increased risk of upper GI cancer death (95% CI 14–59%), 28% increased risk of heart disease death (95% CI 17–40%), and 12% increased risk of stroke death (95% CI 2–23%), but no significantly increased risk of death from cancer at other sites. These elevated risks were present in male smokers, male non-smokers, and females, nearly all never-smokers.

This is just a small sampling of the literature. (You can find plenty more to read at Google Scholar.) As with the many reports connecting periodontal disease with cardiovascular disease (CVD), a debate rages on about whether correlation means causation, in the case of periodontal disease and cancer. I don't think it's rocket science. For me, the picture that emerges is one in which chronic inflammation caused by poor oral health sets the stage for more serious illness. (See my earlier post for more info about the connection between inflammation and cancer.)  I think further research will probably turn up some surprising connections between oral bacteria and cancer, but we don't have to wait for additional research to begin taking oral hygiene seriously as a potential way to head off cancer and CVD. There's no downside to treating your mouth right. The upside may well be years of extra life. That's what the handwriting on the wall is saying at this point.

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Political division is nothing new. Throughout American history there have been numerous flare ups in which the political arena was more than just tense but incideniary. In a letter addressed to William Hamilton in 1800, Thomas Jefferson once lamented about how an emotional fervor had swept over the populace in regards to a certain political issue at the time. It disturbed him greatly to see how these political issues seemed to seep into every area of life and even affect people's interpersonal relationships. At one point in the letter he states:

"I never considered a difference of opinion in politics, in religion, in philosophy, as cause for withdrawing from a friend."

Today, we Americans find ourselves in a similar situation, with our political environment even more splintered due to a number of factors. The advent of mass digital media, siloed identity-driven political groups, and a societal lack of understanding of basic discursive fundamentals all contribute to the problem.

Civil discourse has fallen to an all time low.

The question that the American populace needs to ask itself now is: how do we fix it?


Discursive fundamentals need to be taught to preserve free expression

In a 2017 Free Speech and Tolerance Survey by Cato, it was found that 71% of Americans believe that political correctness had silenced important discussions necessary to our society. Many have pointed to draconian university policies regarding political correctness as a contributing factor to this phenomenon.

It's a great irony that, colleges, once true bastions of free-speech, counterculture and progressiveness, have now devolved into reactionary tribal politics.

Many years ago, one could count on the fact that universities would be the first places where you could espouse and debate any controversial idea without consequence. The decline of staple subjects that deal with the wisdom of the ancients, historical reference points, and civic discourse could be to blame for this exaggerated partisanship boiling on campuses.

Young people seeking an education are given a disservice when fed biased ideology, even if such ideology is presented with the best of intentions. Politics are but one small sliver for society and the human condition at large. Universities would do well to instead teach the principles of healthy discourse and engagement across the ideological spectrum.

The fundamentals of logic, debate and the rich artistic heritage of western civilization need to be the central focus of an education. They help to create a well-rounded citizen that can deal with controversial political issues.

It has been found that in the abstract, college students generally support and endorse the first amendment, but there's a catch when it comes to actually practicing it. This was explored in a Gallup survey titled: Free Expression on Campus: What college students think about First amendment issues.

In their findings the authors state:

"The vast majority say free speech is important to democracy and favor an open learning environment that promotes the airing of a wide variety of ideas. However, the actions of some students in recent years — from milder actions such as claiming to be threatened by messages written in chalk promoting Trump's candidacy to the most extreme acts of engaging in violence to stop attempted speeches — raise issues of just how committed college students are to
upholding First Amendment ideals.

Most college students do not condone more aggressive actions to squelch speech, like violence and shouting down speakers, although there are some who do. However, students do support many policies or actions that place limits on speech, including free speech zones, speech codes and campus prohibitions on hate speech, suggesting that their commitment to free speech has limits. As one example, barely a majority think handing out literature on controversial issues is "always acceptable."

With this in mind, the problems seen on college campuses are also being seen on a whole through other pockets of society and regular everyday civic discourse. Look no further than the dreaded and cliche prospect of political discussion at Thanksgiving dinner.

Talking politics at Thanksgiving dinner

As a result of this increased tribalization of views, it's becoming increasingly more difficult to engage in polite conversation with people possessing opposing viewpoints. The authors of a recent Hidden Tribes study broke down the political "tribes" in which many find themselves in:

  • Progressive Activists: younger, highly engaged, secular, cosmopolitan, angry.
  • Traditional Liberals: older, retired, open to compromise, rational, cautious.
  • Passive Liberals: unhappy, insecure, distrustful, disillusioned.
  • Politically Disengaged: young, low income, distrustful, detached, patriotic, conspiratorial
  • Moderates: engaged, civic-minded, middle-of-the-road, pessimistic, Protestant.
  • Traditional Conservatives: religious, middle class, patriotic, moralistic.
  • Devoted Conservatives: white, retired, highly engaged, uncompromising,
    Patriotic.

Understanding these different viewpoints and the hidden tribes we may belong to will be essential in having conversations with those we disagree with. This might just come to a head when it's Thanksgiving and you have a mix of many different personalities, ages, and viewpoints.

It's interesting to note the authors found that:

"Tribe membership shows strong reliability in predicting views across different political topics."

You'll find that depending on what group you identify with, that nearly 100 percent of the time you'll believe in the same way the rest of your group constituents do.

Here are some statistics on differing viewpoints according to political party:

  • 51% of staunch liberals say it's "morally acceptable" to punch Nazis.
  • 53% of Republicans favor stripping U.S. citizenship from people who burn the American flag.
  • 51% of Democrats support a law that requires Americans use transgender people's preferred gender pronouns.
  • 65% of Republicans say NFL players should be fired if they refuse to stand for the anthem.
  • 58% of Democrats say employers should punish employees for offensive Facebook posts.
  • 47% of Republicans favor bans on building new mosques.

Understanding the fact that tribal membership indicates what you believe, can help you return to the fundamentals for proper political engagement

Here are some guidelines for civic discourse that might come in handy:

  • Avoid logical fallacies. Essentially at the core, a logical fallacy is anything that detracts from the debate and seeks to attack the person rather than the idea and stray from the topic at hand.
  • Practice inclusion and listen to who you're speaking to.
  • Have the idea that there is nothing out of bounds for inquiry or conversation once you get down to an even stronger or new perspective of whatever you were discussing.
  • Keep in mind the maxim of : Do not listen with the intent to reply. But with the intent to understand.
  • We're not trying to proselytize nor shout others down with our rhetoric, but come to understand one another again.
  • If we're tied too closely to some in-group we no longer become an individual but a clone of someone else's ideology.

Civic discourse in the divisive age

Debate and civic discourse is inherently messy. Add into the mix an ignorance of history, rabid politicization and debased political discourse, you can see that it will be very difficult in mending this discursive staple of a functional civilization.

There is still hope that this great divide can be mended, because it has to be. The Hidden Tribes authors at one point state:

"In the era of social media and partisan news outlets, America's differences have become
dangerously tribal, fueled by a culture of outrage and taking offense. For the combatants,
the other side can no longer be tolerated, and no price is too high to defeat them.
These tensions are poisoning personal relationships, consuming our politics and
putting our democracy in peril.


Once a country has become tribalized, debates about contested issues from
immigration and trade to economic management, climate change and national security,
become shaped by larger tribal identities. Policy debate gives way to tribal conflicts.
Polarization and tribalism are self-reinforcing and will likely continue to accelerate.
The work of rebuilding our fragmented society needs to start now. It extends from
re-connecting people across the lines of division in local communities all the way to
building a renewed sense of national identity: a bigger story of us."

We need to start teaching people how to approach subjects from less of an emotional or baseless educational bias or identity, especially in the event that the subject matter could be construed to be controversial or uncomfortable.

This will be the beginning of a new era of understanding, inclusion and the defeat of regressive philosophies that threaten the core of our nation and civilization.