What Are the Factors That Cause Malocclusion, and How Do Prescribed Sleep Appliances Affect Occlusion?

DeWitt C. Wilkerson, DMD | Steve Lamberg, DDS, DABDSM | Leopoldo P. Correa, BDS, MS

DeWitt C. Wilkerson, DMD, maintains a private practice in St. Petersburg, Florida, and is the immediate past president of the American Academy for Oral Systemic Health and the director of dental medicine at the Dawson Academy.

Steve Lamberg, DDS, DABDSM, is the founder of the Pediatric and Adult Airway Network of New York and maintains a private practice in Northport, New York.

Leopoldo P. Correa, BDS, MS, is an associate professor and the director of dental sleep medicine at the Craniofacial Pain Center in the Department of Diagnostic Sciences at the Tufts University School of Dental Medicine.

DeWitt C. Wilkerson, DMD: Dental malocclusions have multiple causative factors, including genetic predisposition, internal derangements of the temporomandibular joint, airway/breathing disorders, and tongue-tie/swallowing disorders.

Although craniofacial growth and development, including dental occlusion, is largely guided by genetics that are passed from parents to children, gene expression and cell development can be modified by environmental factors, which can also affect craniofacial growth and development. This is known as epigenetics.

Internal derangements of the temporomandibular joint can occur due to trauma, disc displacement, hard- and soft-tissue growths, inflammatory arthritides, and hormonal imbalance. These changes can significantly affect dental malocclusion.

Airway/breathing disorders, which also contribute to malocclusion, can be caused by enlarged adenoids or tonsils, food or environmental allergies, and obstructed nasal passages (eg, from deviated septum, polyps, sinus infections, turbinate hypertrophy, and/or narrow passages). These can result in upper airway resistance syndrome, in which physiologic nasal breathing may convert to mouth breathing as a compensatory measure. Mouth breathing requires a low tongue posture, which changes the "neutral zone" effects of muscles on the developing maxilla in growing children. The results can include a narrowed maxilla, maxillary retrusion, elongation of the premaxilla, and a forward thrust of the tongue. The maxillary dentition may reflect a V- or Omega-shaped arch, crowding, supraeruption, a "gummy smile," or an anterior open bite. The mandibular arch may be restricted in growth with a crowded dentition. Third molar impaction is common in both arches. This is an example of epigenetic influence on dental malocclusion.

Tongue-tie and swallowing disorders produce similar outcomes to upper airway resistance syndrome and mouth breathing, including dental malocclusions.

The treatment of airway and breathing disorders, including snoring and obstructive sleep apnea, has been shown to influence dental malocclusions. The use of sleep appliances, which anteriorly reposition the mandible, may produce posterior open bites and maxillary retrusion. When utilizing sleep appliances, the design of the appliance and the management of the occlusion are important clinical considerations.

Steve Lamberg, DDS, DABDSM: Most clinicians are aware that the use of mandibular advancement appliances may cause occlusal changes, which are more frequent than they are significant, but few appreciate the hidden factors that are responsible for the occlusal disharmonies that we face on a daily basis.

Habitual mouth breathing, open mouth posture at rest, immature swallow, tongue thrust, and incorrect tongue posture are among a host of orofacial myofunctional disorders that collectively, represent the most common causes of the malocclusions that dentists are expected to "fix." The presence of an untreated orofacial myofunctional disorder may also be responsible for relapses after treatment. Whether it is functional ankyloglossia, anatomic nasal resistance factors, or behavioral issues that are preventing the tongue from finding a home on the roof of the palate, the "glossus appliance" (ie, the tongue) has its way with the growth and development of the facial bones that house the teeth.

From high-arched palate to retruded mandible, tongue thrust, deviated septum, and crowded dentition-everything is set in motion by the patient's mode of breathing. In addition, fetal development cannot be ignored, including the effects of decreased newborn breastfeeding times and soft weaning foods, which can contribute to poor development of the craniofacial and respiratory complexes and associated dysfunctional breathing.

It is no longer desirable or acceptable to restore smiles without first evaluating airway health. Clinicians are at a "crossroads" of traditional dentistry and airway health. Until recently, we have been compensating for dystrophic jaws with ceramic artwork, while leaving the bigger health problem unaddressed. As a profession, let's get excited about the shape of the palate (ie, floor of the nose). Let's do whatever is possible to alleviate nasal resistance, help correct mouth breathing, and restore the airway to a healthy status.

Now that we better understand the interrelatedness of the craniofacial and respiratory complexes, dentistry has entered into a new era, and there is no turning back. Let's all take the next step together, and finally, to borrow a phrase from John Kois, DMD, MSD, make this an "Always."

Leopoldo P. Correa, BDS, MS: There have been many concepts proposed for the evaluation of dental occlusion. These concepts mostly have been dentally static positions, designed for bilateral balance with forces vertically aligned on the teeth. Occlusion should be considered not only as a static concept but also as a dynamic one that can affect the craniofacial and cervical systems. For a stable dental occlusion, there must be a confluence of balanced muscle action, properly positioned temporomandibular joints, and distributed guiding contacts in the closing movement.

Oral appliances to manage obstructive sleep apnea function by repositioning the lower jaw in a forward position during sleep, which advances the tongue and results in improved upper airway patency. The forces created by these devices, their design features, and the extent of the therapeutic jaw protrusion may produce disharmony within the temporomandibular joints, neck, and masticatory muscles. These symptoms commonly appear during the first few weeks of therapy and are managed by making subtle adjustments to the appliances. Several studies have demonstrated the occlusal effects of these devices when used long-term.

According to current clinical guidelines, following diagnosis and referral from a sleep physician, qualified dentists can use oral appliances among patients with mild to moderate obstructive sleep apnea or in particular cases of severe sleep apnea in which patients are noncompliant with or unable to use positive airway pressure therapy. Clinical techniques, such as the use of morning jaw aligners and the performance of jaw exercises, have been developed in an attempt to minimize occlusal symptoms during oral appliance therapy; however, these approaches require further research to confirm their validity and long-term efficacy. As the field of dental sleep medicine continues to grow, it is essential that dentists who use oral appliances for obstructive sleep apnea also understand the management of potential side effects, including occlusal symptoms, and adhere to the standards of dental sleep medicine practice.