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We are in unprecedented times. Still. This pandemic is wearing on all of us, and we yearn to return to precedented times. As we learn more about this disease – its effects and aftereffects – it is becoming clear that COVID-19 is much more than just a respiratory illness. This has been covered (and will continue to be covered) here on Science Based Medicine and elsewhere, but suffice it to say that it seems that every day we are hearing about another manifestation of this illness.

Until recently, most of us in the dental field have not had to contend with any overt effects of COVID-19 other than desperately hoping that our inadequate PPE protects us from the potentially infectious spit that is flying all around us every day. Lately, however, there have been growing reports of dental issues that are being attributed to what is now being called “Post-Acute COVID-19 Syndrome (PACS)”, symptoms that linger long after the acute phase of the illness has resolved. In the lay public, people with PACS are called “long haulers” and their symptoms usually include persistent loss of taste and smell, fatigue, shortness of breath, sleep disorders, impaired memory and cognition (“brain fog”), and others. The incidence, natural history, and etiology of these symptoms is currently unknown. Emerging research has also proposed mechanisms by which oral health can directly or indirectly influence the transmission of the coronavirus and the severity of COVID-19.

Early in the pandemic, the dental community focused on how closures of dental offices would affect oral health. Initially, we feared that people missing their cleanings and examinations, small dental problems becoming larger ones, and other concerns would occur, and once dental offices re-opened, we attempted to reassure the public that it was safe to visit their dentist. Then, in June 2020, papers in the British Dental Journal and Medical Hypotheses floated the hypothesis that periodontal (gum) disease could be linked to the severity of COVID-19. Of course, correlation does not equal causation, but it has been shown that oral pathogens can cause respiratory illnesses – particularly aspiration pneumonia – and thus could explain a causative relationship between the two. Possible mechanisms of action include direct aspiration of oral pathogens into the lungs, periodontal disease-associated enzymes in saliva modifying oral mucosal surfaces to promote adhesion and colonization by respiratory pathogens which are then aspirated into the lungs, and inflammatory related cytokines could alter respiratory epithelium to promote infection by respiratory pathogens. Whether these observed phenomena can be extrapolated to SARS-CoV-2 infection remains to be seen. But now the dental milieu was more directly implicated in COVID-19. Of course, it could be that people who are at risk for COVID-19 (age, health, lifestyle and habits, and other co-morbidities) are also the same risk factors for periodontal disease, so that muddies the waters a bit.

The fallout

In early November, I saw a tweet from a woman who stated that her 12 year old son’s tooth fell out suddenly and without warning after having COVID-19 several months prior. This got my attention because it is extremely rare for a permanent tooth to loosen and exfoliate in a person of that age, except in instances of trauma. Other possible causes, such as Juvenile Periodontitis, can occur, but the presentation is different than this one. In this case, it was claimed that the tooth fell out painlessly and bloodlessly. This story was picked up in The New York Times, Huffington Post, and other media outlets and before long, other people were relating their COVID-related tooth loss stories on social media. Many dental problems were blamed upon the viral infection, including tooth loss, tooth mobility, increased incidence of tooth decay, discoloration of teeth, and chipped teeth, among others. Could this be yet another post-COVID complication?

As we here at Science Based Medicine frequently preach, before one can ask if something happened, one must first ask could it happen. Yes we must be open to all possibilities, but in any science-based investigation, we must ask ourselves if something is plausible before we can even entertain the idea of whether something actually occurred as reported. With this tenet as my lodestone, my first reaction when I heard about sudden tooth loss in otherwise healthy individuals was to summarily dismiss it as yet another overblown, hyperbolic misinterpretation of reality. After all, teeth don’t just fall out in otherwise healthy individuals, especially in young people. Preposterous! However, another tenet in science base inquiry which must be respected is the null hypothesis. There are many definitions of the null hypothesis, depending on how it’s used, but at its essence it can be boiled down to “start from scratch, assume nothing, and build a case from there”. In other words in the context of our scenario, begin by assuming that there is no correlation between reported dental issues and past or current SARS-CoV-2 infection and seek out good evidence. So I endeavored to do just that, hoping to either confirm or refute the claims put forth by those whom I truly believe are being sincere. And as a science detective, I wish I could shed some light on this issue, but if I want to be intellectually honest, I can’t do that at this point in time.

Disappointing, I know, but bear with me.

What we know

The first thing I did was to do a literature search using scientific resources such as PubMed, the database at the Center for Evidence Based Dentistry at the American Dental Association, Google Scholar, and others. Unfortunately, there is no literature that documents the cases being shared on social media and in the lay press as of this writing. Perhaps this is because there isn’t a true connection, but it could also mean that the science hasn’t yet caught up with the observed phenomena. After all, this is a novel virus, and we are just scratching the surface in our understanding of how it affects us all.

The second thing I did was to look for precedence with other viral infections as it relates to tooth loss. Infections of all types share many common features and presentations, so it is plausible that if other viral infections have caused similar dental problems as was claimed with the coronavirus, then it wouldn’t be unreasonable to extrapolate them to the current situation. Unfortunately, there was very little in the literature to suggest that this had historical precedence. The closest thing I could find was a case report study regarding a purported link between trigeminal herpes zoster (shingles) and spontaneous tooth exfoliation. Sadly, the authors obviously have little to no knowledge about periodontal disease, as the case reports given show profound ignorance of the etiology and progression of periodontal disease, and in no way do the reports support the conclusions they draw from the study. Despite their claims to the contrary, the case reports show evidence of massive pre-existing periodontal destruction, and the tooth loss they document is what would be expected in the natural course of the disease, not as a result of a viral infection.

Since there was no hard evidence in the literature about rapid, spontaneous tooth loss due to COVID-19 (or any other viral or bacterial diseases), the third thing I did was to grasp for possible mechanisms of action for this to happen. Again, I was disappointed. There are some tantalizing islands of data that, if you squint hard enough, could be construed as possible explanations for COVID-induced tooth loss, but they are merely suggestive of a connection, not definitive. For example, it is recognized that SARS-CoV-2 binds to ACE2 receptors in the body. One study demonstrated that the mouth, especially the tongue, contains a high number of ACE2 receptors, which could provide a rich environment for the coronavirus to take hold. In another speculative paper, it was hypothesized the periodontal pocket (the gum crevice that surrounds each tooth and which bleeds when you floss the night before your dental checkup) could be a reservoir for the virus, a safe harbor where SARS-CoV-2 could find its biological niche, lie low, and attack when the time was right. These two studies are necessary to explain a possible role in tooth loss, but they aren’t sufficient to do so. There are still a lot of dots to connect, a lot of data to be collected, a lot of missing pieces to the puzzle before any definitive correlation between PACS and dental problems can be acknowledged. Yes, we are learning that the coronavirus can affect the vascular system. Yes, we are learning that there can be neurological side effects post-COVID-19. And yes, our teeth and surrounding tissues have both vascular and neurological components. That still doesn’t give us enough confidence to say that Post-Acute COVID-19 Syndrome can cause tooth loss. That’s not how teeth work.

Conclusion: ¯\_(ツ)_/¯

I regret to inform you, dear readers, that this post has generated more heat than light. I accepted this assignment hoping that the research would be more definitive in its conclusions, that we could either confirm that dental issues are yet another set of problems that COVID victims would have to deal with or write it all off as the far-fetched claims of a handful of cranks seeking likes and follows on social media.

Sadly, we can do neither.

If we can draw any conclusions at this point, we can determine that either tooth loss is a part of PACS and the science just hasn’t caught up with it yet, or that what has been reported is a coincidental or misdiagnosed issue. Only time will tell.

What is lacking in every case I’ve seen posted online in Facebook groups and other social media outlets is any sort of legitimate documentation – no before and after radiographs, no dental charting, and no reports from dentists themselves. There have been no clinicians or researchers from universities or dental associations who have stepped up to suggest that this is a legitimate aftereffect of the illness. In order for researchers to seriously study this phenomenon, we need more systematic and thorough documentation and study. Until then, these isolated cases – anecdotes – have to be taken with a grain of salt. We have no reason to doubt the sincerity of people making claims of dental destruction following recovery from COVID, but until this is confirmed scientifically, we must remain skeptical yet open-minded.

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Posted by Grant Ritchey

A Science-Based Dentist. Co-host of the Prism Podcast with Clay Jones, where we analyze the spectrum of scientific, rational, and critical thought. Find us on Twitter: Grant: @skepticaldds Clay: @skepticpedi Prism Podcast: @prismpodcast