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The mouth is connected to a complex system of muscles that are involved in life's most essential functions—eating and breathing.

Beyond smiling: Recognizing a dysfunctional swallow

Nov. 16, 2023
The mouth does so much more than smiling. Dental hygienists can play a role in discovering a dysfunctional swallow and possibly save a life.

Editor's note: Originally published November 12, 2020. Updated November 2023.

Thursday afternoon. Two more patients, then done. This day has gone on forever. You rub the back of your neck. Grabbing the next chart, you head to the waiting room, looking at the name. A bell goes off in your head … this guy. As you pass Sally at the desk, you both do an eye roll. You take a deep breath and open the door.

There he is, filling the worn burgundy chair. His loud T-shirt screams the name of a popular beer. It almost covers his ample stomach on which his hands are folded. He sighs and begins the process of getting up as he sees you.

“Mr. Jones, come on in.” You smile at him as he makes a grimace. He lumbers across the reception area. He turns the wrong way at the end of the hallway as he has done every time for years.

“Like a maze back here,” he grumbles. You follow him to your operatory and open his chart as he noisily flops into the chair.

“How have you been, Mr. Jones?” You put on your mask.

“Oh, fair to middling,” he replies.

“How has your health been? Have you been sick or in the hospital?” you ask, glancing at his medical history. He takes typical medications for a middle-aged man: statin for cholesterol, beta blocker for blood pressure, HCTZ, and metformin for blood sugar maintenance.

“Nope. Been good.”

“Any new medicines?”

“Nope.” Now he seems annoyed. “I don’t know what this has to do with cleaning my teeth. Oh, wait. I got gourd or something. Taking a new pill.”

“You mean GERD? What are you taking?”

“Can’t remember. My wife puts them out.”

“OK … what color is it? Do you know the first letter?” You bring up drugs.com on your computer. After some discussion, he asserts the pill is omeprazole. You make a note in his medical history update.

After he denies any dental issues, you go ahead and perform his oral health care. His breath fogs your mirror continually. His lips tighten as you try to debride his lower front teeth, which have heavy plaque and food debris. The doctor comes in at the worst time, as you’re looking for lesions on his tongue.

“Hey, Doc! How you hitting them?”

“Good, Jonesy! Hit a 44 last week. Any problems with your teeth?”

“Yeah, Doc, these teeth are sensitive when cold beer hits them.” He points to his maxillary canine and premolars, which have significant abfraction lesions on the class V area. “My wife says food gets stuck there too.”

“Oh, yeah, you’ve got some ditched-out roots,” observes the doctor as he pulls back the upper lip. “She’ll show you how not to brush so hard.” He nods toward you. “Come back and I will fill them in with bonding.”

You internally grumble as Mr. Jones just told you he didn’t have any dental problems. He and the doctor talk about golf, and Mr. Jones gets up to leave. As you write up his chart, you recall the several times you have told him his abfraction areas are from bruxism.

Mr. Jones comes back and gets the bonding done. He is thrilled with how much better his teeth look. Two weeks later, Sally appears at the door of your operatory, white as a ghost. She tells you that Mr. Jones choked to death last night.

You gasp and sit down. A momentary sense of dread washes over you. Was there something you could have done?

Recognizing a dysfunctional swallow

Dental hygienists are experts in prevention of more than just dental disease. We know all about teeth, gums, oral cancer, caries, and periodontal disease. We recognize oral signs of systemic disease, or do we? We can tell a lot about a patient’s hygiene habits even when they tell us the opposite.

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We know that chewing and swallowing are the main purpose of the oral cavity. There’s a social component too: speaking, communicating, and smiling, or rather, facial expression. Dentists are always advertising about making a smile prettier, but what about the mouth’s function as part of the craniofacial respiratory complex?

Dentists adjust a filling with articulating paper and make sure it is in occlusion. What about the actual occluding or chewing? How well do the teeth function to process food? Teeth do not work alone. They are part of a functioning system, which is the entrance to the digestive tract. The tongue and facial muscles work with the teeth to form a safe bolus, which is transported down the esophagus.

In a properly functioning masticatory process, food or liquid should not be in the buccal vestibule at all. The first indication that Mr. Jones had dysfunctional mastication is his complaint that food debris gets stuck in the abfracted lesions of his upper teeth. Dental professionals have basic knowledge of how food is processed in the mouth.

Proper chewing is essential to good digestion and uptake of nutrients. Mr. Jones’s metformin prescription is an indication that he is not getting the full benefit of what he eats.

The modern diet is so soft that it does not seem to need much mastication. Early humans ate what they could find or hunt raw. Jaws were much larger. Malocclusion and tooth decay practically did not exist.1

Many modern children are not chewing at all for the first several years of life. They go from a bottle, to soft cereal, to baby food. Then sippy cups and soft food pushed up from a pouch, graduating to chicken nuggets, cheesy noodles, and yogurt. This trend is devastating to the development of good oral architecture. Baby-led weaning and giving babies whole food help to establish good oral musculature from the orbicularis oris to the esophagus.

The four phases of swallowing

There are four phases in a normal swallow.2 In the oral preparatory phase, solids are removed from a utensil with the lips and placed behind the front teeth where chewing begins to take place. Chewing is rotational, with the food crushed and moved from side to side by the tongue and facial muscles of mastication. To jog your memory, those muscles are masseter, temporalis, and medial and lateral pterygoid. The buccinator is considered an assistant muscle to mastication.  Well-developed buccinator muscles should prevent food from going outside the teeth. For Mr. Jones, his facial muscles never really helped the food stay inside of the teeth.

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Once the food is masticated, it enters into the second phase of swallowing, the oral transit phase. Once in this phase, the lateral borders of the tongue help to gather the bolus in the middle third of the tongue, and the cranial nerves associated with the tongue move the bolus.

Liquids should go in the mouth without contacting the buccal surfaces.

The tongue transports the food or liquid to the pharynx (pharyngeal phase) for swallowing, and then into the esophageal phase. Mr. Jones’s cold liquid sensitivity in maxillary buccal surfaces indicates dysfunction in the first phase of swallowing. Therefore, cold sensitivity—a very common dental complaint—may require more than desensitizing products to be resolved.

Observing facial muscle movement can detect an improper swallow. Rinsing out is not the same as drinking. But we never watch our patients actually eat or drink. In the transit phase, the tongue should be working almost completely independent of the other orofacial muscles to propel the bolus toward the pharynx.

In the pharyngeal phase, the bolus enters the pharynx, where a series of reflexlike actions take place to close the airway and guide the bolus to the esophagus. Dysfunction in this phase can result in “swallowing the wrong way” and coughing. A patient with a chronic dry cough may have dysfunction in this phase.

In the esophageal phase, the bolus is pushed into the esophagus. Once it passes the upper sphincter, it is pushed down by gravity and peristalsis. By this point, the mouth should absolutely be closed and the bolus should slide down from the tongue to the stomach without air bubbles. Frequent burping is an indication of taking in air (aerophagia) during any of the phases of swallowing.

A basic knowledge of the normal swallow is essential for dental professionals. It is what the mouth is supposed to do. A perfect cosmetic smile does not digest food to sustain life. Mr. Jones could have lived a longer, healthier life. You could be contributing to longevity and better life quality for your patients by acting on these observations.

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References

  1. Boyd KL. Darwinian dentistry part 1: An evolutionary perspective on the etiology of malocclusion. J Am Orthod Soc. 2011;34-40.
  2. The four phases of the normal adult swallow process. Amy Speech & Language Therapy, Inc. https://www.amyspeechlanguagetherapy.com/the-normal-swallowing-process.html

Elizabeth Dooher-Anthony, RDH, has been a practicing hygienist for over 30 years. She lives in Rochester, NY, with her husband Michael. She has a daughter, Kelly. She has been doing oral care in nursing facilities for over 11 years. She is also a speaker and writer. She created Serdentity, a course for dental professionals on peaceful patient interactions, and she published a book of the same name. You can reach her through her website serdentity.com.