Dental Considerations

Duchenne affects orofacial muscles (muscles of the face and the mouth) and influences orofacial function (chewing, swallowing, etc.). There is a high prevalence of malocclusion (the incorrect relationship between the teeth of the upper and lower dental arches as they approach each other when the jaw closes). An increased expansion of the lower dental arch, compared to the upper dental arch, may result in open bites (the lower and upper teeth not coming in contact with each other when the teeth /jaws close) and crossbites (the lower and upper teeth coming in contact incorrectly and ineffectively). This results in a significantly weak bite force. As you get older, weakness in the orofacial muscles may affect orofacial function leading to difficulty chewing and swallowing.

Changes in Structure

The orofacial skeleton is the structure of the face and mouth, which includes the position of the teeth and shape of the dental arches. Habits, such as thumb sucking and breathing with an open mouth, as well as orofacial muscle strength and function play a role in the development (shape) of the orofacial skeleton.

Tongue Changes

In Duchenne, the tongue may enlarge with age while the strength and function of tongue weakens. As the tongue enlarges and becomes weaker, it may have difficulty maintaining the movement and pressure required for chewing, swallowing and speech. An enlarged tongue can also contribute to worsening dental malocclusion, changing the appearance of the face and causing more difficulties with chewing. Keeping the tongue in, and avoiding “mouth breathing” may help to minimize this change.

Changes in Function

As you get older, your tongue muscle, muscles in and around your mouth, and the muscles used for swallowing become progressively weaker, causing eating to be a slower and more difficult process.

Alterations in Chewing and Swallowing

If you are found to have malocculusion of the teeth, you may have issues chewing your food completely, making it more difficult to swallow. As a result of inefficient chewing along with weakened swallowing muscles may lead to an accumulation of unswallowed “residue” in the throat. This accumulation causes a feeling of choking or of food “stuck in the throat.” This residue sitting in the throat may be aspirated into the lungs, increasing the risk of aspiration pneumonia. Minimizing solid food during meals (thinning foods or following meals with at least 3 swallows of water) may help to decrease the residue left in the throat.

Chewing Interventions

The progressive weakening of the chewing muscles may be slowed down with exercise. Encouraging exercises, such as chewing sugar free chewing gum, may help to keep the muscles needed for chewing stronger.

Swallowing Interventions

Difficulty swallowing is called dysphagia. More information about managing dysphagia can be found here.

Dental Hygiene

Poor dental hygiene can lead to issues with tooth decay and gum disease. Dental hygiene can be an issue if the jaw is difficult to open and the tongue is difficult to move out of the way. Abnormal dental findings often include high levels of decay, heavy plaque especially around the lower teeth, unhealthy gums, and poor dentition.

Children should begin seeking dental care very early. Maintaining a healthy diet, practicing daily oral hygiene (brushing and flossing), fluoride prophylaxis, using sealants appropriately and seeing a dentist every 6 months are extremely important.

As people living with Duchenne get older, reduced upper limb function makes oral hygiene more difficult. Parents/caregivers will need to be shown how to effectively brush the teeth of another. This may include how to move the tongue away to get access to all surfaces of the teeth. Areas between the tongue and cheek also need to be included (with a weaker muscles, there is less “natural cleaning” of this area). For this reason it is also important to rinse the mouth with water after every meal to remove any unswallowed residue.

Orthodontia

Given the oropharyngeal changes inherent in this diagnosis, orthodontic treatments should not be initiated by anyone without a thorough understanding of Duchenne. Speak to your primary care provider or neuromuscular team about orthodontic recommendations.

In addition, preventive removal of wisdom teeth may not be appropriate for all. This procedure should be evaluated from an individual benefit-risk perspective, including the risk of anesthesia, aspiration, and of osteonecrosis (severe bone disease) of the jaw caused by molar extraction when patients are also taking bisphosphonates.

Dental Procedures

When a person with Duchenne undergoes general anesthesia, they are at risk for a number of serious problems.

Dental Procedure Recommendations

Dental hygiene and proper care are extremely important and help to reduce the incidence of oral and respiratory infections, specifically pneumonia. Dentistry generally can and should be performed with minimal or no anesthesia to provide the patient with maximal physical and emotional comfort. Local anesthetics (i.e. novocaine, lidocaine) or inhaled nitrous oxide (“laughing gas”) are both generally safe to use in people with Duchenne regardless of their pulmonary function or ambulation. Any oxygen use should be cautioned in people with Duchenne who are non-ambulatory and/or have abnormal pulmonary function.

Nitrous Oxide

The use of inhaled anesthetics (i.e. Halothane, Isoflurane, Seroflurane) can result in serious complications. One complication is rhabdomyolysis, which is the massive breakdown of skeletal muscle tissue which can ultimately damage the kidneys. Another is hyperkalemia, which is the release of too much potassium into the bloodstream which can result in cardiac arrest (“heart attack”).

Nitrous oxide (“laughing gas”), used during office dental procedures by an observant dentist, is an accepted and safe practice, even though it is inhaled. Nitrous oxide is a commonly used inhaled anesthetic in dentistry, emergency, and ambulatory centers. Advantages of nitrous oxide include:

Impressive safety profile
Provides excellent minimal and moderate sedation for anxious patients
Quickly and easily absorbed into the bloodstream and the brain, as well as easily eliminated from the body

Following nitrous oxide, patients are generally given oxygen for 1-2 minutes in order to “wash out” the gas from the respiratory system. The oxygen is administered in an “open system” (mixed with room air), so the oxygen concentration is not 100%. The use of an “oxygen washout” is also a safe and appropriate practice for people with Duchenne.

Local Anesthetics

In many dental procedures, local anesthetics are often given via injection. Commonly used anesthetics include Novocaine or Lidocaine. Local anesthetics are considered safe for use in Duchenne.

Oxygen use

Many parents are concerned with the use of oxygen is mentioned. The use of oxygen in an ambulatory patient with normal lung function poses minimal threat. The use of oxygen by itself is a concern when its intended use is to treat hypoventilation in a non-ambulatory patient with decreased pulmonary function.

Patients with Duchenne who have pulmonary dysfunction (abnormal breathing) should consider receiving dental care requiring general anesthesia in a hospital or surgery center staffed with an anesthesiologist, and equipped to monitor intra-operative respiratory functioning and to manage potential respiratory and cardiac emergencies.

Non-ambulatory patients with Duchenne have weaker respiratory muscles. Therefore, as the disease progresses, it becomes difficult to cough and to take deep breaths. Up to a point, shallow breathing can provide the body with adequate oxygen supply and adequate removal of carbon dioxide. That delicate balance of oxygen and carbon dioxide allows breathing to continue. When extra or supplemental oxygen is given, this delicate balance is disturbed. The respiratory center may get the false impression that the body has enough oxygen, and the drive to breathe diminishes. Without effective breathing, carbon dioxide can build to dangerous levels (called hypercapnia).

Oxygen should never be given without constantly monitoring the level of carbon dioxide CO2 in the expired breath (the “end-tidal CO₂”) or the CO₂ level in blood. A normal end tidal CO₂ is between 30-45 mmHg. A CO₂ level (greater than 45 mmHg) indicates that CO₂ is not being expelled from the body. Non-invasive ventilation (Bi-PAP via mouthpiece or nasal cannula) will assist with the mechanical process of breathing, delivery of oxygen and removal of CO₂.

Dental Procedure Facts to Remember

Dentistry generally can, and should, be performed with the minimal amount of anesthesia possible while providing the patient maximal physical and emotional comfort.
Local anesthetics, nitrous oxide, and an oxygen “wash out” are safe for most patients with Duchenne, especially patients who are ambulatory with normal pulmonary function (normal breathing).
Patients with Duchenne who have pulmonary dysfunction (abnormal breathing) should consider receiving dental care requiring general anesthesia in a hospital or surgery center staffed with an anesthesiologist, and equipped to monitor intra-operative respiratory functioning and to manage potential respiratory and cardiac emergencies.

References

Becker DE, Rosenberg M, “Nitrous Oxide and the Inhalations Anesthetics,” Anesth Prog, 2008, winter, 55(4): 124-131.
“Respiratory Care of the Patient with Duchenne Muscular Dystrophy,” American Thoracic Society Document, Am J Respir Crit Care Med, 2004, 170: 456-465.
Birnkrant D, Panitch HB, Benditt JO, Boitano LJ, Carter ER, Cwik VA, Finder JD, Iannaccone ST, Jacobson LE, Kohn GL, Motoyama EK, Moxley RT, Schroth MK, Sharma GD and Sussman MD, “American College of Chest Physicians Consensus Statement on the Respiratory and Related Management of Patients with Duchenne Muscular Dystrophy Undergoing Anesthesia or Sedation,” Chest, 2007, 132:1977-1986.

Acknowledgements

Pulmonologists(Dr. Jonathan Finder, Dr. Hemant Sawnani, and Dr. Richard Shell), dentistry (Dr. Elizabeth Vroom), and anesthesia (Dr. Norbert Weidner)

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