A Surprising Reason Why You Get Cavities 

Heather is a middle aged woman who came to see me for snoring. She snored so loudly that her husband has to sleep in another room. She also noted that she gained over 100 pounds over the past 20 years working as a night shift nurse. She recently started working during the days, but found it difficult to have the energy to do her job, or spend quality time with her husband. When I looked in her mouth, I noticed that she was missing most of her teeth, and the few she had were rotting away. During our discussion, she lamented that when she was a teenager growing up in Jamaica, she was thin, healthy, vibrant, and with a full set of healthy teeth. Now she’s 110 pounds overweight, has nasal congestion, diabetes, high blood pressure, high cholesterol and will be needing dentures soon.
This is a common problem that I see almost every day in practice. Thin, healthy men and women who grew up eating naturally, come to the US for a better life, only to gain lots of weight, develop a number of chronic medical conditions and seeing doctors almost full-time after retiring. Shift work also takes a major toll on your health in general. More often than not, they lose an excessive amount of teeth due to cavities and tooth decay.
Traditionally, cavities are thought to happen when bacteria that normally live in your mouth feed on excessive amounts of sugar, which lead to plaque buildup over teeth. Over time, acid production underneath plaque starts to dissolve your enamel, creating cavities. Risk factors for cavities include: location of teeth (usually molars), sugary or acidic foods, frequent snacking, bed-time feedings for infants, inadequate brushing, dry mouth and acid reflux.
Heather didn’t have a habit of eating too much candy. She brushed her teeth and flossed regularly. Over the years, as she gained weight and her snoring got worse, she began to breathe more through her mouth, especially at night. Contrary to popular opinion, breathing through your mouth narrows your airway even further. This set off 3 events that aggravated her tooth decay, leading to multiple extractions:
Stuffy nose
Having a stuffy nose will cause you to mouth breathe. Oftentimes, high blood pressure medications can lower your melatonin levels by lowering sympathetic tone levels (fight or flight response). Since the melatonin production pathway passes through the superior cervical ganglion (which regulates sympathetic functioning), lowering sympathetic tone may lower melatonin.
In addition, having obstructive sleep apnea also is linked with an imbalanced nervous system inside the nose, where there’s too much parasympathetic tone (rest, relaxation and reproduction), leading to swelling of the nasal membranes and turbinates. This leads to a stuffy nose. 
Breathing through your mouth also causes drying of your saliva, which has acid neutralizing properties. 
Obstructive sleep apnea
In my book, Sleep Interrupted: A physician reveals the #1 reason why so many of us are sick and tired, I described my sleep-breathing paradigm, which begins with the obstruction–reflux–obstruction feedback loop. This causes more swelling in your throat, causing more obstruction. If you have any residual lymphoid tissues like tonsils or adenoids, you’ll get even more narrowing of your upper airway.
Acid reflux
What comes up from your stomach is not only acid, but includes bile, digestive enzymes, and bacteria. Even if you take acid reflux medications, your stomach juices can still come up with each apnea episode, bringing up less acidic juices. It’s also been shown that pepsin, a major stomach enzyme, can reach your nose, sinuses, ears and lungs. 
The perfect storm 
If you place all three of the above conditions together (nasal congestion, acid, and dry mouth), you’ll end up with the perfect storm for cavities.
But wait—there’s more…
Mouth breathing can also prevent proper facial growth and development. The most extreme example of this is what you see in children with adenoid facies: open mouth posture, head forward position, and recessed and narrowed jaws (see example). This relative underdevelopment of the jaws lead to having a smaller mouth, leading to dental crowning, which narrows your airway even further. If you have excessive dental extractions as a young child for braces or when older as an adult, then your mouth gets even smaller. 
After improving Heather’s nasal congestion with allergy medications, she was able to breathe better again. She was found to have moderate obstructive sleep apnea is now sleeping much better with CPAP.  
If you are someone who was healthy, skinny, and had great teeth before you immigrated to a modern, “Western” country such as the United States, did you experience similar dental problems like what happened to Heather? Do you have or suspect that you may have obstructive sleep apnea? Please enter your comments in the space below.

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2 thoughts on “A Surprising Reason Why You Get Cavities 

  1. Thank you Dr. Park for expressing the connection of mouth to body so eloquently. I advocate incorporating dental auxiliary in teaching dental patients the risk factors, signs and symptoms of OSA. So many of our patients suffer with rampant caries and periodontal disease…untreated OSA is a significant factor. I would like to reference this article during my lectures throughout the country.

  2. That’s terrible :( However, I don’t think it’s fair to blame immigration for the problem. Growth patterns are established in early childhood, by the age of 5. Open mouth posture increases the gonial angle and occlusal plane, which suppresses condylar growth leading to hypoplasia of the ramus, anterior-posterior maxilla, and accentuation of the curve of Spee. It should be possible to screen children for risk factors before they enter elementary school if you know what to look for.

    Small arches get a bad rep but it’s possible to have sleep apnea even with full arches. A mandible with a steep gonial angle may appear nominally normal in size but still compromise the airway. In fact, my theory is that early development of sleep apnea makes one more prone to normal arches, as nocturnal bruxism simulates consumption of a hard diet, the other risk factor for small jaws. The main reason crowding becomes a problem in this group is due to flattening the curve of Spee, which requires a larger arch and which pretty much guarantees that there will be some amount of transverse discrepancy as well. Aesthetically, such people can even appear normal because they adjust their facial posture to compensate.

    Another interesting point about reflux is that I’m told it actually reduces cavity risk, according to a dentist on Reddit at least. She claimed it causes teeth to become smooth and slimy, which is more resistant to cavity formation. I suspect it still erodes enamel just not in a cavity pattern, more consistently across the teeth. One comment I often get is that my erosion can’t be reflux because it causes a pattern of decay focused on the backs of teeth while mine is across all the teeth, closer to that of a chronic soda drinker. I think there’s something to that, patterns of decay with sleep apnea are different than those of normal people (I haven’t had a soda in many years and can’t eat acidic foods due to sensitivity). Another said it was the combination of bruxism and reflux that caused my decay problems, that either by themselves wouldn’t be enough, and mouth breathing just adds insult at that point.