1 INTRODUCTION

Pierre Robin (1934) used the monoblock mandible advancement appliance for the purpose of treating patients with obstructive sleep apnea for the first time.¹ Following this, Boraz treated pediatric OSA patients.² Cartwright and Samelson (1982)³ reported the effectiveness of the tongue retaining device (TRD) which retains the tongue in the bulb of the device. Meier-Ewert (1984)⁴ used Esmarch–Heiberg manipulation, which opens the airway of a general anesthetized patient, and developed the Esmarch appliance. The tongue retaining appliance represented by the TRD, and the mandible advancing type represented by the Esmarch, are the two main types of oral appliance. Thereafter, other oral appliances were developed such as the adjustable type, which can adjust the amount of mandible advancement. Currently, more than 55 oral appliances (OAs) are on the market.⁵

2 PATIENT SELECTION

In 2006, the Standards of Practice Committee of the American Academy of Sleep Medicine published the reports Oral Appliance for Snoring and Obstructive Sleep Apnea: A Review⁶ and Practice Parameters for the Treatment of Snoring and Obstructive Sleep Apnea with Oral Appliances: An Update for 2005.⁷ Oral appliances are indicated for use with patients with primary snoring and with mild to moderate OSA, who prefer them to continuous positive airway pressure (CPAP) therapy, or who do not respond to CPAP, are not appropriate candidates for CPAP, or who have failed treatment attempts with CPAP.

3 PROCEDURES FOR ORAL APPLIANCE THERAPY

The procedures for oral appliance therapy are as follows.

4 ORAL APPLIANCE VARIATIONS

With so many different oral appliances available, selection of a specific appliance may appear somewhat difficult, but they are designed around a few major themes. Oral appliances can be classified by mode of action or design variation. Nearly all appliances fall into one of two categories: the tongue retaining type and the mandibular advancing type.

4.1 TONGUE RETAINING DEVICE (TRD)

(See Fig. 11.1A&B.)

Fig. 11.1

The TRD functions by holding the tongue in a forward position by means of a suction bulb. When the tongue is in this position, the device keeps the tongue from collapsing during sleep and obstructing the airway in the throat.

4.2 MANDIBULAR ADVANCING TYPE

The mandibular advancing type functions by repositioning and maintaining the mandible in a protruded position during sleep. This serves to open the airway by indirectly pulling the tongue forward, keeping the soft palate attached to the tongue (oral seal) by the negative pressure occurring in the mouth and making it more rigid. It also holds the lower jaw and other structures in a stable position to prevent opening of the mouth.

4.2.1 NON-TITRATABLE TYPE

The mandibular advancing and non-titratable type of oral appliance is a custom-made monoblock device connected by two separate arches (maxillary and mandibular) without an advancing mechanism. Several versions are listed below.

1. Esmarch appliance (Fig. 11.2A&B). Meier-Ewert developed this mandibular advancing and non-titratable type of oral appliance, using the Esmarch–Heiberg manipulation method, which opens the airway of the general anesthetized patient.

2. Nocturnal airway patency appliance (NAPA) (Fig. 11.3A &B). With this appliance, the mandible is in a protruded position during sleep. This serves to open the airway by indirectly pulling the tongue forward and keeping the soft palate attached to the tongue. This device has a hole in the front extended portion, to enable inhaling from the mouth.

3. Mandibular repositioner (Fig. 11.4A&B). This appliance also has a hole in the front to enable inhaling from the mouth.

4. Snore guard (Fig. 11.5A&B). This appliance is made of heat-activated resin.

Fig. 11.2

Fig. 11.3

Fig. 11.4

Fig. 11.5

4.2.2 TITRATABLE TYPE

The mandibular advancing and titratable type of oral appliance is a custom-made two-piece appliance composed of two separate arches (maxillary and mandibular) containing an advancing mechanism. Examples are listed below.

1. Klearway (Fig. 11.6A&B). This custom-made two-piece appliance is composed of two separate arches (maxillary and mandibular) to advance the mandible with a screw (0.25 mm/1 turn) to determine the ideal forward position of the mandible required to adequately open the airway. A total of 44 forward positions are available in increments of 0.25 mm, which covers a full 11.0 mm range of anterior–posterior movement.

2. Thornton adjustable positioner (TAP) (Fig. 11.7A&B). This appliance is composed of two separate arches (maxillary and mandibular) containing an advancing mechanism and a base and hook assembly with an internal adjustment mechanism.

3. Herbst (Fig. 11.8A&B). This device contains an advancing mechanism which has two sets of pistons and tubes to keep the mandible in the forward position required to adequately open the airway.

Fig. 11.6

Fig. 11.7

Fig. 11.8

Oral appliances may be used alone or in combination with other means of treating OSA, including weight control, surgery, or CPAP.

Recently, oral appliance therapy was performed along with CPAP therapy to reduce the pressure flow of the CPAP machine; however, there will be a growing number of combination treatments developed in the near future. We currently have no data available concerning the percentage of patients treated with both the oral appliance and CPAP therapy. However, we have a number of patients using the CPAP on a daily basis who prefer to use an oral appliance for traveling, even though the CPAP machines are getting smaller.

5 POSTOPERATIVE MANAGEMENT AND SIDE EFFECTS OF ORAL APPLIANCE

Follow-up dental appointments at least every 6 months to monitor subjective effectiveness, comfort, and temporomandibular joint and dental status are needed.

5.1 CHANGING THE OCCLUSION

Patients have to use oral appliances for long periods of time to maintain the airway patency every night. Consequently, the vigorous force applied to the teeth changes the occlusion. The occlusal change of the patient during oral appliance therapy conducted for 12 years can be seen in Figures 11.9 and 11.10. Sometimes teeth and/or prosthetic crowns can be broken by this force (Fig. 11.11). We should not only take care of the teeth, but also the occlusion and temporomandibular joint.

Fig. 11.9

Fig. 11.10

Fig. 11.11

5.3 ORTHODONTIC TREATMENT AND AIRWAY

Orthodontic treatment can influence the size and the function of the airway.

Cases 1 & 2

These patients were sisters aged 12 years 11 months and 11 years 9 months, so they were still growing. They complained about their maxillary protrusion. The elder sister was treated by the extraction of five teeth because she had one congenitally missing tooth and one root resorbed tooth. The younger sister, however, was treated by non-extraction with the Herbst appliance. The treatment term was 3 years 11 months for the elder sister and 3 years 2 months for the younger sister. Both sisters had a typical muscle strain on the chin when they closed the lips together (Fig. 11.12).

Fig. 11.12

When we superimposed the cephalograms at the baseline of these sisters, there were a few differences between the sisters before treatment; for instance, the nose of the elder sister was bigger than that of the younger sister. However, the superimposition of the cephalograms of both cases revealed these sisters were almost identical. Their lower pharynx was the same width at the baseline (Fig. 11.13).

Fig. 11.13

In both cases, the muscle strain on the chin disappeared after orthodontic treatment. Both sisters recovered with better facial appearance, and had a satisfactory result. There was little difference between the appearance of the sisters (Fig. 11.14).

Fig. 11.14

When we superimposed the cephalograms of the baseline and the result of the elder sister, only her nose grew; the other part did not grow at all and the width of the lower pharynx was reduced from 12 mm to 10 mm. Conversely, the mandible of the younger sister grew a lot. As a consequence, the width of the lower pharynx was increased from 12 mm to 17 mm. The lower pharynxes of the sisters were the same, 12 mm before the treatment; however, the lower pharynx of elder sister reduced to 10 mm and that of younger sister increased to 17 mm. Thus, there was a total difference of 7 mm after the treatment (Fig. 11.15).

Fig. 11.15

The result of the treatment looks almost the same from the outward appearance; there were, however, significant differences between the sisters inside the face involving the size of the airway. It may be that orthodontic treatment influences the size of the airway; evidence for this is still being investigated.

6 CRANIOFACIAL PATTERN OF OSA

The craniofacial characteristics of obstructive sleep apnea patients have been reported as follows.

We reported that craniofacial patterns of OSA patients were: the dolichofacial pattern (increased anterior facial height) by cephalometric analysis of Ricketts’ and OSA patients having their mandible retropositioned; a long soft palate; decreased airway space; and a lowered position of the hyoid bone.¹⁵

7 IMPORTANCE OF THE ORAL SEAL TOBREATHING

Frankel¹⁹ noted that the impact of the ‘space problem’ in the physiology of the orofacial complex has been emphasized by Moss.^20–22 He maintains that the proper functioning of the digestive and respiratory systems depends on a functionally adequate patency of the oral and the nasopharyngeal passageways. This assumption receives significant support from the work of Bosma²³ who emphasized the impact of adequate space conditions in the physiology of the orofacial complex, with particular emphasis on airway maintenance. The life-sustaining functions of breathing as well as intake and transport of food are dependent on the adequate patency of these spaces and the proper functioning of the various valves as seen in Figure 11.16.

Fig. 11.16

Frankel emphasized that there are four valves in the dentofacial skeleton: the V1 nasal valve, the V2 lip valve (the so-called lip seal), the V3 tongue and soft palate valve (the so-called oral seal) and the V4 epiglottis valve, and that we could maintain physiological atmospheric pressure in the oral and nasopharyngeal spaces in the presence of a competent oral seal.

Bosma²³ emphasized that the posterior soft tissue barrier formed by the soft palate and the tongue is an important factor for airway maintenance. The positional stabilization of the pharyngeal airway is the initial manifestation of the distinctive coordination of posture. The physiological relevance of the infantile performance of the stabilization of the airway is identified by its impairment in Pierre Robin syndrome. When these afflicted children are lying on their backs, the apposition of the tongue to the palate cannot take place because of the hypoplasia of the dorsal portion of the palate mostly associated with the cleft. The infantile mechanism of pharyngeal airway maintenance fails to operate, and the tongue falls downward and backward, occluding the pharynx. In a prone position, the tongue approximates the palate by the force of gravity, permitting nasal portal respiration. Bosma²³ noted that mandibular retrusion in Pierre Robin syndrome may be interpreted as an appropriate component of a regional failure of a positional function which emphasizes the physiological relevance of the muscular barrier separating the oral cavity from the pharyngeal space.

We propose the hypothesis that the mechanism of thoracic negative pressure inhibits the backward and downward growth of the mandible. When the obstruction occurs in the pharyngeal area, the patient wants to move down the diaphragm to take in air; accordingly, pressure is produced in the chest. The negative pressure produced in the chest (of the obstructive sleep apnea patient) is detected by intra-esophageal pressure monitoring. The deformity of the chest appears when the patient inhales, which is the opposite of that which occurs in breathing. The mechanism of negative pressure inhibits the growth of the mandible as follows (Fig. 11.17).

Fig. 11.17

If we stand by this hypothesis and the functional matrix hypothesis, it is easier to interpret why OSA patients tend to have the dolichofacial pattern (long face) and lower positioned hyoid bone, longer soft palate and narrow airway. These may be the result of negative pressure in the chest. This negative pressure may cause funnel chest (Fig. 11.18). Castiglione²⁵ reported that 82% of 23 children affected by chronic upper airway obstruction showed pectus excavatum and 82% showed enlarged tonsils and adenoids. If this negative pressure disappears as a result of the removal of the tonsils or adenoids, or by orthodontic treatment to improve patency of the airway, the mandible may grow normally, and we could prevent or reduce sleep apnea in the future.

Fig. 11.18