ORAL APPLIANCES IN THE TREATMENT OF SNORING AND SLEEP APNEA

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ORAL APPLIANCES IN THE TREATMENT OF SNORING AND SLEEP APNEA Richard P. Millman, MD, Cynthia L. Rosenberg, DDS, MSD, and Naomi R. Kramer, MD

Over the past decade, interest in oral applicance therapy for snoring and sleep apnea has increased. This article reviews the types of appliances, their possible mechanisms of action, and their efficacy. We also provide a logical approach for the clinician to determine the patients who should be referred for oral appliance therapy.

TYPES OF APPLIANCES

Multiple devices have been developed for the treatment of obstructive sleep a ~ n e a . ' ~There , * ~ are basically two major types-those that advance the tongue and those that advance the mandible. The tongue retaining device (TRD) was one of the first appliances d e ~ e l o p e d .It~is , ~a custom-made appliance with an anterior bulb (Fig. 1). It fits over both the upper and lower dental arches. The tongue is held in a forward position in the anterior compartment by suction. A flange fits between the lips and the teeth and holds the device and tongue forward in the oral cavity. This article appeared in Clinics in Chest Medicine, Vol. 19, No. 1, March 1998, as part of an issue on Sleep Disorders.

From the Sleep Disorders Center of Lifespan Hospitals, Rhode Island Hospital (RPM,NRK); and Brown University School of Medicine (RPM, CLR, NRK), Providence, Rhode Island OTOLARYNGOLOGIC CLINICS OF NORTH AMERICA VOLUME 31 * NUMBER 6 * DECEMBER 1998

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Figure 1. The tongue retaining device. The unit fits over upper and lower dental arches and the tongue is held forward in the anterior compartment by suction. (Courtesy of Pro Orthodontic Laboratory, Racine, Wf.)

Several mandibular positioning devices have been ~tudied.’,~,~,’~, Although most require dental impressions, bite registration, and fabrication by a dental l a b ~ r a t o r ydevices ,~~ are now available with a thermal labile material such as the Snore Guard (Hays and Meade, Inc., Albuquerque, NM) that can be molded to the patient’s teeth in the physician’s or dentist’s office.26Inexpensive devices with unproven efficacy can even be purchased in pharmacies or through the Internet. Such devices can be molded and fitted by the patients themselves. Many of the mandibular advancement appliances, such as the Nocturnal Airway Patency Appliance (NAPA) (Great Lakes Orthodontics, Ltd., Tonawanda, NY), are fixed, although some, such as the Herbst appliance (Fig. 2), are adjustable. The latter have distinct advantages in that they allow for additional jaw advancement if a patient’s obstructive sleep apnea is undertreated or less advancement if the patient has excessive temporomandibular joint (TMJ)pain or discomfort. 11,133-24,26

MECHANISM OF ACTION

Dental devices produce changes in the shape and function of the upper airway during sleep. The effects of airway dimension have been assessed by cephalometric radiographs (Fig. 3), which give a two-dimensional view of the airway, typically in the awake, upright position. That technique is limited in its ability to fully document three-dimensional changes during sleep. Alternative approaches have included CT or MR

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Figure 2. An adjustable soft Herbst appliance. (Courtesy of Great Lakes Orthodontics, Ltd., Tonawanda, NY.)

imaging of the upper airway or video endoscopy, all of which potentially can provide more information about three-dimensional changes with therapy. Johnson et all4 examined the effect of mandibular protrusion in 10 patients with documented sleep apnea. They took two upright lateral cephalometric radiographs. The first was taken in the position of relaxation (terminal hinge position) and the second, with maximal forward mandibular posturing. They found that their patients were able to move their

Figure 3. Cephalometricparameters. PAS = posterior airway space; S = sella; N = nasion; H = hyoid bone; A = A point; PNS = posterior nasal spine; PNS-P = soft palate length; MP-H = hyoid to mandibular plane distance; PFH = posterior facial height. (From Eveloff SE, Rosenberg CL, Carlisle CC, et al: Efficacy of a Herbst mandibular advancement device in obstructive sleep apnea. Am J Respir Crit Care Med 149:905, 1995; with permission.)

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mandibles anteriorly an average of 6.9 mm. That led to an increase in posterior airway space (PAS) from the base of the tongue to the posterior pharyngeal wall (see Fig. 3) of 56%. That measurement varied widely, however, and the PAS increased in only 8 of the 10 patients. Ferguson and colleagues* examined the effect of mandibular and tongue protrusion on the cross-sectional area and shape of the hypopharynx, oropharynx, and velopharynx in 10 patients with sleep apnea and five nonapneic controls using awake video endoscopy. The patients were studied in the supine position. There were no differences in the effects of mandibular or tongue protrusion on upper airway caliber between patients and controls. Mandibular protrusion increased the cross-sectional area of the hypopharynx and oropharynx, whereas tongue protrusion increased the cross-sectional area of all three regions of the pharynx (Fig. 4). One would potentially expect that voluntary tongue protrusion would reflect the tongue protrusion seen with the TRD. Mandibular advancement appliances, however, appear to have a somewhat different effect on airway dimension than voluntary forward movement of the mandible. One explanation is that it is possible that mandibular advancement devices both advance the mandible and may produce downward rotation of the mandible to varying degrees, opening up the vertical dimension. Schmidt-Nowara et a1,26using a one-piece nonadjustable Snore Guard to pull the mandible forward, found an increase in the posterior airway space with that orthotic device.z6That is similar to the changes seen with voluntary mandibular protrusion and is supported by the study by Menn et al;z who also found small, but significant, increases in PAS with a different fixed mandibular repositioning device. Other authors, using a fixed mandibular advancement device2 or an adjustable Herbst appliance: however, found no change in the PAS measurement. PAS is a static measurement made in the awake, upright position and may not reflect the dynamics of tongue collapse into the hypopharynx with sleep. Eveloff and colleagues7demonstrated a shortening of the distance from the hyoid bone to the midmandibular plane in 19 patients treated with a Herbst appliance. Similar findings were shown by other authors.z,zzA hyoid bone positioned level with the genial tubercle increases the efficacy of the geniohyoid muscle in pulling the tongue forward and opening the airway.27 Another alteration that has been shown to occur with mandibular advancement devices is the opening of the velopharynx, an effect that was not demonstrated by Ferguson with voluntary mandibular posturing.8 Eveloff and colleagues7demonstrated shortening of the soft palate length in patients responding to the Herbst device. Bonham et aIz also showed an increase in the superior airway space with their device. Lowe and colleaguesz0performed video endoscopy in nine awake patients treated with a Klearway (Great Lakes Orthodontics, Ltd., Tonawanda, NY) ad-

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Figure 4. Changes in cross-sectional area of the hypopharynx,oropharynx,and velopharynx with various positions of the mandible and tongue. B = full retrusion; R = normal bite-rest position; IA = incisors aligned; 50% = half maximal protrusion; MAX = maximal protrusion. All data are normalized to the rest position (R). (From Ferguson KA, Love LL, Ryan CF: Effect of mandibular and tongue protrusion on upper airway size during wakefulness. Am J Respir Crit Care Med 155:1748, 1997; with permission.)

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Figure 5. The Klearway adjustable oral appliance. (Courtesy of Great Lakes Orthodontics, Ltd., Tonawanda, NY.)

justable mandibular advancement device (Fig. 5). They found a statistically significant increase in the cross-sectional area of the velopharynx, with only small increases in the oropharynx and hypopharynx.20That suggests that mandibular advancement influences the movement of other soft tissues in the upper pharynx. EFFICACY OF ORAL APPLIANCES The American Sleep Disorders Association recently commissioned a review of all the articles written about oral appliance therapy for obstructive sleep apnea and snoring.25That review found that, in all published studies in which snoring was assessed, snoring improved in 73%-100% of patients using a variety of types of appliances. The review also looked at 20 publications reporting the efficacy of oral appliances on obstructive sleep apnea. Those 20 studies represented 304 patients. Overall, 51% achieved normal breathing, as defined by an apnea hypopnea index (AHI) of fewer than 10 episodes per hour with therapy. Thirty-nine percent of patients with an AH1 greater than 20 still had an AH1 above that level with therapy. No type of oral appliance appeared to be better than any other in the review. Table 1 outlines some of the results of the major studies discussed in that review and results reported in more recent manuscripts. It is difficult to predict from those studies which patients would respond to an oral appliance. Several ~ t ~ d i e ~have ~ , ~found ~ , ~that ~ ,treat~ 6 ment success is inversely related to initial AHI-patients with severe dis-

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Table 1. EFFICACY OF ORAL APPLIANCE THERAPY IN OBSTRUCTIVE SLEEP APNEA

Type of Appliance

TRD Snore Guard Herbst NAPA Other MAD

Reference

3 4 8 25 5 7 11 13 22

Patients (n) 14 12

25 20 24 19 16 14

23

% Patients with AH1 < l o with

Treatment 36 58 48 40 46 53 69 71 52

AH1 = apnea hypopnea index: TRD = tongue retaining device; NAPA = nocturnal airway patency device; MAD = mandibular advancement device.

ease did not have as good a response as those with mild to moderate disease. There does not appear to be a placebo effect with an oral appliance. The mere presence of an appliance in the oral cavity does not lead to improvement in sleep apnea; forward movement of the tongue or mandible must be present. A recent crossover study using a Snore Guard appliance compared the effect of the appliance without any mandibular advancement with the appliance advancing the mandible approximately 6 to 8 mm.12The authors demonstrated an improvement in sleep apnea only when the device actually advanced the mandible. Two studies compared mandibular advancement oral appliances to treatment with nasal continuous positive airway pressure (CPAP).6,9 Both studies were randomized crossover evaluations and both demonstrated that the oral appliance was effective in mild to moderate disease and less effective than nasal CPAP in more severe cases. In both studies, the patients strongly preferred the oral appliances over nasal CPAP because of comfort. SIDE EFFECTS

Studies have suggested that excessive salivation, dryness of the mouth, or transient discomfort may prevent early acceptance of the app l i a n ~ eThe . ~ ~major long-term problems appear to be TMJ or jaw discomfort and movement of the teeth. Tooth movement may result in changes in occlusion, most commonly a posterior open bite and decreased anterior overjet. Those side effects can be minimized by avoiding excessive advancement of the mandible with therapy and adjusting the appliance to reduce pressure on the anterior teeth. The patient should not have signifi-

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cant pain in the morning or difficulty opening his or her jaw when he or she first gets up. APPROACH TO THE PATIENT It is important that the patient's sleep apnea be diagnosed adequately prior to therapy. Because the device may have significant impact on the teeth and TMJ joint, the appliance should be fitted by an experienced dentist or orthodontist. Not all patients with sleep apnea are good candidates for a dental device. A complete dental examination of patients should include evaluation of teeth, dental restorations, occlusion, soft tissue, periodontal health, temporomandibular joint function, mandibular movement, and craniofacial skeletal type. A baseline cephalometric radiograph and access to other dental radiographs are helpful in completing patient assessment. First, enough teeth must be present to support the appliance-generally, six teeth in each arch, with at least one healthy posterior tooth in each quadrant. Methodology is available for edentulous patients,I5 but not much experience has been reported in the literature. Patients should not have significant periodontal disease and all necessary dental restorative treatment should be completed prior to fitting the appliance. The patient should be able to protrude his or her mandible forward approximately 5 mm without TMJ discomfort. It is also important that there be enough space in the pharynx to allow the appliance to work. A patient with an extremely deep set palate, a long uvula, and enlarged tonsils therefore may not be a good candidate for an oral appliance and, instead, should receive nasal CPAP or, possibly, pharyngeal surgery. It is difficult to predict which patients should receive oral appliance therapy. One study7suggested that the addition of several cephalometric parameters to the baseline AH1 improves the ability to predict the AH1 on therapy with an oral appliance. It also has been suggested that fluoroscopy may be helpful in predicting who would be helped by mandibular advancement.16The data, however, are very limited. Presently, we cannot predict the potential success of any dental appliance based on anatomic considerations alone.Is As with any therapy for sleep apnea, patients may report subjective improvement that cannot be substantiated on follow-up testing. Patients with snoring or mild sleep apnea probably do not need follow-up polysomnography unless symptoms fail to resolve.' Patients with moderate to severe sleep apnea, however, should undergo polysomnography with the appliance in place after final adjustments have been made.I A recent survey of dentists who make oral appliances suggested that 95% of patients receiving treatment had a baseline polysomnographic study,17but, surprisingly, only 18%received a posttreatment study. Furthermore, noctur-

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nal pulse oximetry was perceived to be an adequate substitute for polysomnography by 37% of the dentists surveyed. That type of problem can be obviated by having the dentist or orthodontist work closely with the sleep specialist.

CONCLUSIONS Oral appliances are becoming an accepted mode of therapy for patients with sleep apnea. They appear to be effective in patients with mild to moderate disease and are generally accepted more easily than nasal CPAP.

References 1. American Sleep Disorders Association Report: Practice parameters for the treatment of snoring and obstructive sleep apnea with oral appliances. Sleep 18(6):511-513, 1995 2. Bonham PE, Currier GF, Orr WC, el al: The effect of a modified functional appliance on obstructive sleep apnea. Am J Orthod Dentofacial Orthop 94:384-392, 1988 3. Cartwright RD, Samelson CF: The effects of a nonsurgical treatment for obstructivesleep apnea. JAMA 2248:705-709,1982 4. Cartwright R, Stefoski D, Caldarelli D, et al: Toward a treatment logic for sleep apnea: The place of the Tongue Retaining Device. Behav Res Ther 26:121-126, 1988 5. Clark GT, Arand D, Chung E, et al: Effect of anterior mandibular positioning on obstructive sleep apnea. American Review of Respiratory Disease 147624-629, 1993 6. Clark GT, Blumenfeld I, Yoffe N, et al: A crossover study comparing the efficacy of continuous positive airway pressure with anterior mandibular positioning devices on patients with obstructive sleep apnea. Chest 109:1477-1483, 1996 7. Eveloff SE, Rosenberg CL, Carlisle CC, et a 1 Efficacy of a Herbst mandibular advancement device in obstructive sleep apnea. Am J Respir Crit Care Med 149:905-909, 1994 8. Ferguson KA, Love LL, Ryan CF: Effect of mandibular and tongue protrusion on upper airway size during wakefulness. Am J Respir Crit Care Med 155:1748-1754,1997 9. Ferguson KA, On0 T, Lowe AA, et al: A randomized crossover study of an oral appliance vs nasal-continuous positive airway pressure in the treatment of mild-moderate obstructive sleep apnea. Chest 109:1269-1275,1996 10. George PT: A modified functional appliance for treatment of obstructive sleep apnea. Journal of Clinical Orthodontics 21:171-175,1987 11. George PT Treatment of snoring and obstructive sleep apnea with a dental device. General Dentistry 413294298, 1993 12. Hans MG, Nelson S, Luks VG, et al: Comparison of two dental devices for treatment of obstructive sleep apnea syndrome (OSAS). Am J Orthod Dentofacial Orthop 111:562570, 1997 13. Ichioka M, Tojo N, Yoshizawa M, et al: A dental device for the treatment of obstructive sleep apnea: A preliminary study. Otolaryngol Head Neck Surg 104:555-558,1991 14. Johnson LM, Arnett CW, Tamborello JA, et a1 Airway changes in relationship to mandibular posturing. Otolaryngol Head Neck Surg 106:143-148,1992 15. Knudson RC, Meyer JB Jr, Montalvo R: Sleep apnea prosthesis for dentate patients. J Prosthet Dent 68:109-111, 1992 16. L'Estrange PR, Battagel JM, Harkness B, et al: A method of studying adaptive changes of the oropharynx to variation in mandibular position in patients with obstructive sleep apnoea. J Oral Rehabil23:699-711,1996 17. Loube DI, Strauss AM: Survey of oral appliance practice among dentists treating obstructive sleep apnea patients. Chest 111:382-386, 1997

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18. Lowe AA: Can we predict the success of dental appliance therapy for the treatment of OSA based on anatomical considerations? Sleep 16:593-595, 1993 19. Lowe AA: Dental appliances for the treatment of snoring and obstructive sleep apnea.

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In Kryger MH, Roth T, Dement WC (eds): Principles of Sleep Medicine, ed 2. Philadelphia, WB Saunders, 1994 Lowe AA, Sjoholm TT,Ozbek M, et a1 The effects of Kleanvay oral appliances on airway size and obstmctive sleep apnea. Proceedings of the Cherry Blossom Symposium, 1997 in press Meier-Ewert K, Brosig B: Treatment of sleep apnea by prosthetic mandibular advancement. In Peter H, Podszius T, von Wichert P (eds): Sleep Related Disorders and Internal Medicine. Berlin, Springer-Verlag, 1987 Menn SJ, Loube DI, Morgan TD, et al: The mandibular repositioning device: Role in the treatment of obstructive sleep apnea. Sleep 19:794-800, 1996 Nakazawa Y, Sakamoto T, Yasutake R, et al: Treatment of sleep apnea with prosthetic mandibular advancement (PMA). Sleep 15:499-504,1992 O'Sullivan RA, Hillman DR, Mateljan R, et al: Mandibular advancement splint: An appliance to treat snoring and obstructive sleep apnea. Am J Respir Crit Care Med 151:19P

198,1995 25. Schmidt-Nowara WW, Lowe A, Wiegand L, et a1 Oral appliances for the treatment of snoring and obstructive sleep apnea: A review. Sleep 18:501-510, 1995 26. Schmidt-Nowara WW, Meade TE, Hays MB: Treatment of snoring and obstructive sleep apnea with a dental orthosis. Chest 99:1378-1385, 1991 27. Thurow RC: Atlas of Orthodontic Principles. St. Louis, CV Mosby, 1977, pp 3 7 4 3

Address reprint requests to Richard P. Millman, MD Division of Pulmonary, Sleep, and Critical Care Medicine APC-479A Rhode Island Hospital 593 Eddy Street Providence, RI 02903