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It has been estimated that nearly 30 million Americans suffer from obstructive sleep apnea (OSA) and that approximately 80% of these cases remain undiagnosed.1 Worldwide, estimates indicate that approximately 4% of men and 2% of women are affected by the condition.2 This sleep disorder is highly prevalent and impactful in our communities. The increased morbidity from type 2 diabetes,3 cardiovascular disease,4 depression,5 and other chronic life-threatening conditions that has been associated with OSA, as well as its connection with an increased risk for traffic and workplace accidents, reinforces its status as a public health concern. Fortunately, the medical and dental communities and the general public as a whole have made great progress in recognizing the importance of diagnosing and treating OSA.
Dental professionals have a critical role to play in helping to better screen for and treat OSA. It has been reported that approximately 58% of Americans visit a dentist at least once per year,6 so there is a clear opportunity for dentists to aid in identifying some of the often misattributed or less obvious symptoms of OSA in patients. In many cases, these symptoms are overlooked or left untreated without a comprehensive exploration into whether or not they are a result of undiagnosed OSA.
For some time, positive airway pressure (PAP) therapy has been universally accepted as the most effective treatment for OSA. However, low adherence rates among patients who cannot or will not use their machines have resulted in the ineffective treatment or undertreatment of many individuals. For these PAP-intolerant patients, oral appliance therapy administered by dentists who specialize in sleep medicine has grown in recognition as a viable treatment option.
Although oral appliance therapy can provide an alternative to PAP therapy, it does present with its own potential side effects, however, and can result in orthodontic changes such as mandibular repositioning and altered occlusal contacts, among others.7 Therefore, it is important for dental professionals to understand that these orthodontic changes may occur and what steps can be taken to mitigate any negative effects on the oral health of their patients.
Potential Appliance-Related Orthodontic Changes
Clinicians need to receive appropriate education and training in order to properly fabricate appliances to treat patients for OSA; however, even the most thoughtfully made appliances can result in a variety of orthodontic changes during oral appliance therapy that clinicians should be prepared to manage.
Changes to Occlusal Contacts
Shifts in occlusal contacts have long been associated with the use of oral appliances, including significant changes in both the upper and lower incisors, the repositioning of molars, and other craniofacial changes.8 Research has demonstrated that there is a relationship between the type of appliance used and the tooth movement or bite changes that result. For example, appliances that maintain stronger areas of pressure have been shown to be more likely to produce tooth movement than appliances that cover every tooth and maintain equal pressure throughout the patient's mouth.7 In addition, softer appliances are less likely to provide occlusal stability for a patient than appliances with a hard acrylic structure.9
When patients present with altered occlusions, dentists should never act alarmed because this could both upset them and put them at risk if they elect to stop undergoing a potentially life-saving therapy as a result. Fortunately, over the years, improvements to the design and functionality of oral appliances have made it easier to manage potential occlusal changes. Dentists are now better able to adjust the devices and treatment regimens to fit each patient's unique needs.
Reduction in Overjet and Overbite
One of the more common and often more noticeable orthodontic changes that dentists may encounter in patients managed with oral appliance therapy is a shift in overjet and overbite. According to the results of one study, more than 85% of patients saw a decrease in overjet and overbite when using an oral appliance.10 Moreover, the degree of change observed in these patients correlated with the size of their initial overjet or overbite. The data indicated that those who had the most significant overjet or overbite at the start of initial treatment were often the ones who experienced the greatest change during continued oral appliance therapy.11 Research has also shown that the reduction in overjet and overbite may be progressive and continue to change over time throughout the treatment.12 Although these changes may be positive for patients with significant overjet or overbite, for patients with a normal bite who undergo long-term oral appliance therapy , these changes can result in the development of malocclusion.
Decrease in Mandibular Crowding
Another orthodontic change that can be anticipated with long-term use of oral appliance therapy is a reduction in mandibular crowding. Mandibular crowding can be identified as discrepancies in the positions of the teeth and available space relative to the four permanent incisors. When analyzing what is causing mandibular crowding, there are many variables involved, including the direction of mandibular growth, oral and perioral musculature, incisor and molar inclination, and early loss of deciduous molars.13 With the use of an oral appliance over time, typically, crowding of the mandibular arch decreases and mandibular intercanine and intermolar width increases,12 and research has shown that these changes predominantly occur at a constant rate.14
Development of a Posterior Open Bite
Prolonged oral appliance therapy can result in the development of a posterior open bite. A posterior open bite, which can be defined as the lack of occlusion between a number of teeth in one or both opposing posterior segments,15 can also be associated with and attributed to conditions such as mouth breathing, digit sucking or chewing habits, and interpositional tongue habits. During prolonged use of an oral appliance, the lower incisors are drawn forward, which can create a chain reaction that causes a posterior open bite to develop.12 One study demonstrated a link between oral appliance therapy and anterior and posterior open bite development in a small number of patients who were treated for an average of more than 3.5 years.16 However, the same study showed no open bite development in patients who underwent oral appliance therapy for less than 6 months.16 In a study of patients who underwent oral appliance therapy for more than 5 years, two-thirds had developed a posterior open bite.17
Development of an Anterior Crossbite
Long-term oral appliance therapy can also contribute to the development of an anterior crossbite, which is a malocclusion resulting from the lingual positioning of the maxillary anterior teeth and their relationship to the mandibular anterior teeth.18 Anterior crossbite can be caused by a number of factors, including crowding in the incisor region, inadequate arch length, and a habit of biting one's upper lip, among many others. When a patient uses an oral appliance for a long-term period, the forward movement of the lower incisors combined with the reduction in overjet or overbite can result in the lower anterior teeth protruding beyond the upper anterior teeth.12 Similar to the development of posterior open bite, research demonstrated that the use of oral appliances for an average of more than 3.5 years resulted in the development of anterior crossbite,16 whereas the use of oral appliances for less than 6 months did not result the same level of change.16
Addressing Appliance-Related Orthodontic Changes
Although orthodontic changes may result from oral appliance therapy, there are a number of methods that can be used to reduce their potential to develop as well as to treat them if they occur.
One of the most effective and straightforward ways to alleviate the side effects of oral appliance therapy is to perform jaw exercises. These exercises can provide relief of the muscle stiffness and general soreness that is often associated with wearing an oral appliance, particularly during the first few weeks of treatment. In addition, they can help to accelerate the repositioning of the mandible to its normal position.19 Research has demonstrated that the performance of jaw exercises or stretches increased bite strength and occlusal contact area when compared with periods of no exercise.19 There is even anecdotal evidence that something as simple as chewing gum in the morning can help to reestablish occlusion.12
Physical therapy is another effective treatment option for the effects resulting from long-term oral appliance use. Its biggest contribution can come in the form of pain relief for patients who are experiencing temporomandibular joint disorders.20 Sometimes, temporomandibular joint pain arises early on during oral appliance therapy when patients are adjusting to overnight use of the device. It can also accompany orthodontic changes such as shifts in occlusal contacts, regression of an overjet or overbite, and more. In addition to helping relieve pain, physical therapy has been shown to be effective over time in improving mobility/function for patients with temporomandibular joint disorders.20
Orthodontics or Fixed Prosthodontics
The use of orthodontics, specifically brackets and wires (not aligners), that utilize elastics to pull the teeth together in the posterior segments can be an effective component of a management program following any side effects from the use of a sleep device. Orthodontic treatment is capable of fundamentally changing static and functional occlusal relationships.21 The goal of treatment is to help patients establish or reestablish proper occlusion. A proper and stable occlusion is a key factor in helping prevent the deterioration of the dentition and its structure. Depending on a patient's individual case and situation, fixed prosthodontics can offer another method that can be used effectively in response to orthodontic changes. Minimally invasive restorations can be beneficial in supporting a patient's tooth structure and maintaining high esthetic value.22
As healthcare professionals, dentists should be aware of how important it is to screen for and effectively treat OSA to improve the long-term systemic health of patients. Regarding oral appliance therapy, one byproduct of treatment can be orthodontic changes in tooth position and occlusion. Although oral appliance therapy may have some consequences, those associated with foregoing the treatment of OSA can be far worse. When patients are fully informed by specialists, many choose to accept the possibility of occlusal changes as a less impactful consequence. By being informed and mindful of these changes, dental professionals can work to mitigate their impact through various strategies and remedies. When both the treatment and its resulting side effects are successfully managed, the patient's quality of life is improved.
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About the Author
Kent Smith, DDS
American Sleep and Breathing Academy
American Board of Dental Sleep Medicine
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