The Week That Wasn't: Mask Cavities, Yosemite Sewage, Cinnamon

Victoria Giardina


July 24, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

This week in medical news, a dentist believes wearing masks may cause cavities, testing revealed coronavirus in Yosemite National Park's sewage, and researchers declared cinnamon improves blood glucose control in prediabetes. But you didn't see these headlines on Medscape Medical News. Here's why.

Do Masks Cause Cavities?

A pediatric dentist in Houston is noticing more patients with cavities and believes face masks are to blame, ABC News reported. The dentist says it's not the face masks that directly cause cavities but rather the way people breathe while wearing them.

"If you're not used to [masks], it really can impede on our comfort of breathing," Piya Gandhi, DDS, owner of two dental practices, said. "So what we tend to do is start breathing through our mouth rather than breathing through our nose. And what happens when you're a chronic mouth breather is that we tend to dry out the mouth, so saliva that usually protects our teeth from cavities is now getting dried out and making us more prone to cavities."

Though a provocative observation, no study has tested the proposed link between wearing a face covering and dental cavities. Without any evidence to back it up, we didn't think this claim was worth our readers' time.

Yosemite Sewage

There have been no confirmed cases of COVID-19 in Yosemite National Park, but testing detected SARS-CoV-2 in the park's raw sewage, the San Francisco Chronicle reported. The Cambridge, Massachusetts, lab that did the testing told county health officials it's possible about 170 people were infected, based on virus levels in the sewage.

It may seem alarming that the virus could have been present in Yosemite without any confirmed cases, which makes this local story of wider interest than usual. But the testing data do not appear to be publicly available or described in a scientific study, making the findings difficult to evaluate and verify for our readers. 

Benefits of Cinnamon in Prediabetes

Cinnamon supplements improved blood sugar control in a study of 51 people with prediabetes, researchers report in the Journal of the Endocrine Society. In the randomized clinical trial, participants took a 500-mg capsule of cinnamon or placebo three times a day over 12 weeks. Researchers compared participants' fasting plasma glucose and oral glucose tolerance at the end of the study with baseline measurements.

"Our 12-week study showed beneficial effects of adding cinnamon to the diet on keeping blood sugar levels stable in participants with prediabetes," Giulio Romeo, MD, a staff physician at the Joslin Diabetes Center and the division of endocrinology at Beth Israel Deaconess Medical Center, Boston, Massachusetts, said in a press release.

Cinnamon's effects on blood glucose have been studied for years, and this trial is not the last word. The study was small and only followed participants for a few months, making it difficult to draw firm conclusions. The study authors call for longer and larger studies to evaluate whether cinnamon can slow progression of prediabetes. We didn't think these results were ready for primetime for our readers yet.

Victoria Giardina is Medscape's editorial intern. She has previously written for The Dr. Oz Show and is currently a National Lifestyle Writer for Her Campus. She can be reached at or on Twitter @VickyRGiardina.

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