On our Facebook page, we linked to an article that appeared two weeks ago in Medical News Today with that title: “Breathing through mouth during sleep may increase tooth decay risk.” Click here to read the original story.
We got an interesting reaction from a follower: “My husband and I both sleep with mouth open. We wake up with dry mouth in the morning. I asked my dentist he replied just use duck tape all around. ??? lol”
Which prompted me to do a critical analysis of this study. The bottom line—the title and the phrasing of the conclusions are overblown.
The first thing we need to understand is that the article from Medical News Today is not the original study but is a reporting of the study. The study itself was published in the Journal of Oral Rehabilitation, a scholarly journal. Medical News Today is merely reporting on the study, as are a number of other publications.
Here is what the study demonstrated: Normal daytime oral pH is 7.3. Normal nighttime oral pH is 7.0. In those study subjects who were forced to breathe through their mouths during sleep, their average oral pH was 6.6.
Now here’s what you need to know about oral pH. 7.0 is neutral. Anything lower than that is acidic. Acids in the mouth can damage enamel. But damage to enamel requires a pH below 5.5. But the average pH in mouth breathers in this study was 6.6, which is well above that threshold. It looks like there is nothing to worry about.
But wait. The article states that the researcher discovered that, “at stages during the night, pH levels inside the mouth dropped to 3.6 in individuals who breathed through their mouths.” THAT is low enough to cause erosion of enamel.
Did it ACTUALLY cause erosion of enamel? No, that wasn’t measured by the study. Did it cause tooth decay, as is suggested by the title? No, the study didn’t get into that either. All of that is conjecture, based on this little fact that “at stages” the pH dropped to 3.6. How long were those stages? It doesn’t say.
The Whole Story is More Complicated Than This
There is a lot going on in your mouth that affects what happens to your teeth. There are buffers in saliva that counteract the acidity created when you eat and mouth bacteria feed on the carbohydrates you eat. There are minerals in your saliva and enzymes that repair the enamel. This idea that there is any decay or other damage to the teeth during the sleep of mouth breathers is a hypothesis based on this one tiny observation. And while the article correctly phrased this hypothesis as “may increase tooth decay risk,” the “may” is lost on too many people. It’s a guess that “may” warrant further study.
So in mouth breathers, “at stages” the pH dropped to 3.6. I’d be interested to know how low the pH dropped “at stages” in the non-mouth breathers. We’re not told. My cynical side leads me to think that little tidbit was left out because the author wanted to sensationalize the findings. But that is only a hypothesis that would need further study to corroborate.
– Dr. David Hall
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