Snoring is the most common respiratory disorder that may interrupt quiet sleep. It is caused by vibration of the soft palate and adjacent structures and causes partial obstruction because of narrowing of the upper airway at the site. Habitual snoring in adults is not only a social problem but also a medical one, which may predispose them to development of obstructive sleep apnea (OSA) 1.
Sleep apnea is usually defined as cessation of air flow into the lungs that lasts for more than 10 s. The severity of sleep apnea is defined primarily by the apnea/hypopnea index – the number of apneas (cessation of air flow for more than 10 s) and hypopneas (variable definitions, usually a significant decrease in air flow) per hour 2. Sleep-related breathing disorder is essentially a disease continuum ranging from simple or primary snoring at one end to OSA at the other 3.
OSA is more common in individuals who are overweight, but it can affect anyone. It is characterized by obstruction of the upper airway during sleep and loud and chronic snoring. OSA is characterized by recurrent episodes of oxygen desaturation during sleep, decreased sleep quality, and excessive daytime sleeping.
It has been associated with amnesia, sexual difficulties, headache, myocardial infarction, hypertension, and personality change 4.
The impact of OSA on a patient’s life is sometimes irreversible; snoring affects the sleep of the bed partner and interrupted sleep at night can cause problems during the day, including sleepiness, loss of concentration, memory malfunction, and impaired performance of common skills such as driving. These factors lead to a decrease in quality of life; if not reversed, OSA can affect the person’s life span 5,6.
Increasing focus is being given to the relationship between OSA syndrome and all-cause and cardiovascular disease-related mortality, but it still largely unclear whether this association is causative or simply speculative and epidemiological. Basically, reliable clinical evidence supports the hypothesis that OSA syndrome might be associated with essential and resistant hypertension, as well as with an incremental risk of developing stroke, cardiac rhythm perturbations (e.g. atrial fibrillation, brady-arrhythmias, supraventricular, and ventricular arrhythmias), coronary artery disease, acute myocardial infarction, and heart failure 7.
The main physical findings that impinge on the airway include an enlargement of the neck circumference, oropharyngeal obstruction, soft palate laxity, nasal obstruction, turbinate hypertrophy, nasal septum deformity, tumors of the nasal cavity, tonsil hypertrophy, macroglossia, retrognathia, and temporomandibular deformities 8.
There is no specific medication for the treatment of snoring, although various pharmacological agents have been used. The main aim is to reduce nasal resistance to promote nasal breathing. These medications may modify tissue properties rather than the anatomy, for example, phosphocholine is a tissue lubricant agent taken intranasally before to sleep. It has the potential to be aspirated into the lung, producing lipoid pneumonia. Because of fatigue and sleep deprivation, depression is a common complication of OSA. Protriptyline (Vivactil) is a tricyclic antidepressant that depresses rapid eye movement (REM) sleep, the period during which the most significant apneas often occur. However, the drug is not used often because of its anticholinergic side effects. A large number of newer antidepressants also decrease REM sleep and thus have the potential to improve sleep apnea. As yet, however, no clear evidence supports their use 9.
Sleep study is the most accurate test for diagnosing sleep apnea. It records what happens with breathing during sleeping. Polysomnogram, a home-based portable monitor, is now available in sleep centers and sleep labs. This monitor records brain activity, eye movement and other muscle activity, breathing, heart rate, and blood pressure. In addition, it records how much air moves in and out of the lungs during sleep and the amount of oxygen in the blood 10,11.
Current treatment for obstructive sleep disorders may be conservative, surgical, or device-based. Conservative methods of treatment aim to prevent collapse or widening of the constricted part of airway during sleep; these include weight loss, change of sleep posture, drug therapy, and the use of intraoral and extraoral appliances. The extraoral devices include nasal dilators, nasopharyngeal lubes, and continuous positive airway pressure (CPAP). The intraoral devices include tongue retaining devices, labial shield devices, palatal lift devices, electrical stimulator devices, and anterior mandibular positioning devices. The consistent feature of all these designs is movement of the mandible forward by several millimeters. The guideline for the optimal amount of forward movement is between 50 and 75% of a patient’s maximum protrusive distance and to maintain the jaw in a forward position even when the patient is asleep 12.
This study was conducted to compare the (a) change in the anatomical relationship of the oropharyngeal airway pace in Class II Angle classification, in patients with complaints of loud snoring, using a Jasper positioning device and a one-piece appliance, and (b) to determine the relationship between the use of these appliances and improvement in snoring and respiratory disturbance.
Materials and methods
Ten male patients of Class II Angle Classification were selected. Their ages ranged between 25 and 50 years and they had a history of habitual loud snoring as reported by themselves, spouses, or sleeping partners, with or without other manifestations of OSA (e.g. excessive daytime sleepiness, restless sleep, etc.).
The selected patients were completely edentulous or partially edentulous, that is, they had at least 10 teeth in each of the maxillary and mandibular arches. None of them had any other sleep disorder-related breathing problems, for example, nasal obstruction, short stocky neck, neuromuscular disorders, Down’s syndrome, Pierre Robin syndrome, amyloidosis, acromegaly, and bronchial asthma, as determined by clinical and radiographic examinations by an otolaryngologist.
All the patients were subjected preprosthetically to the following examinations.
Clinical examination included examination of the oral cavity, examination of the temporomandibular joint, masticatory muscles, and calculation of the BMI (kg/m2).
Nasal examination was performed by anterior rhinoscopy using a speculum with the patient seated with the head slightly tilted back. This was carried out to detect septal deviation, turbinate hypertrophy, nasal polyps, other masses, and internal nasal pathway.
To assess nasal patency, the patients were asked to gently block one nostril at a time with one finger, being careful to avoid compression of the other nostril. The patient then inspired through the unoccluded nostril and the maneuver was repeated with the other nostril. If the examiner heard nasal obstruction, the patient was asked whether nasal occlusion was habitual or not. Unilateral and bilateral nasal obstructions were quoted equally.
Lateral cephalometric radiograph
A lateral cephalometric radiograph was taken using a cross-table technique while the patient was lying down on his back (supine position) (Fig. 1a). Cephalostat was adjusted according to the supine position of the patient. The patient’s head was positioned in the right and the left external auditory meatus. The cassette (film holder) was placed so that it was parallel to the median sagittal plane of the patient’s face. The cephalostat and roentgenographic equipment were adjusted at a fixed distance of 180 cm with a fixed focal film distance. For each patient, the cephalograms were taken for the left side of the head with an exposure time of 2 s (Kodak X-ray films were used at 80 kV/s, Kodak film, Kodak company, New York, USA) 13. The radiograph was traced for each patient. Cephalometric landmarks, linear measurements 14, and total pharyngeal length (TPL) 15 were determined and represented graphically as shown in (Fig. 1b).
After a preprosthetic examination and investigation, two different designs of an anterior mandibular positioning device were constructed for each patient: (a) a Jasper Jumper appliance A and (b) a one-piece appliance B. The patients wore each appliance for 2 months with a definite rest period (2 weeks) between the use of each appliance. A cephalogram was taken preprosthetically and after 2 months of using the appliance.
Roof of the pharynx (R): The point on the posterior pharyngeal wall constructed by a line posterior nasal spine (PNS) to the cross-sectional point of the cranial base and the lateral pterygoid plate.
Posterior nasal spine (PNS): Most posterior point at the sagittal plane on the bony hard palate.
Anterior nasal spine (ANS): The outline of the anterior nasal spine that is a sharp median bony process adjacent to the inferior margin of the anterior aperture of the nose formed by the forward prolongation of the two maxillae.
Palate point (P): The most inferior tip of the soft palate.
Supramentale (B): It represents the deepest point of the symphyseal cavity between infradentale and pogonion.
Gnathion (Gn): The lowest bony point in the median plane of the mandible by bisecting the angle formed by the tangents of the chin and the mandibular base.
Gonion (Go): The point on the body contour of the genial process obtained by bisecting the angle formed by tangents to the mandibular base and ramus.
Mandibular plane (MP): A plane passing through the inferior border of the mandible through Gn and Go.
Hyoidale (H): The most anterior and superior point of the hyoid bone.
P1: Point at the roof of the pharynx.
P4: The most anterior–inferior point at the fourth vertebral corpus (C4).
The linear measurements
Superior anterior airway space (SAAS-1): The distance between the ventral surface of the soft palate and the dorsal surface of the tongue, measured through a point midway between the PNS and the tip of the soft palate, parallel to the line connecting Go and supramentale (B-point).
Superior posterior airway space (SPAS-2): The distance between the posterior pharyngeal wall and the dorsal surface of the soft palate, measured through the point midway between the PNS and the tip of the soft palate, parallel to the line connecting Go and supramentale (B-point).
Middle airway space (MAS-3): The distance between the posterior pharyngeal wall and the dorsal surface of the base of the tongue measured through the posterior tip of the soft palate, parallel to the line connecting Go and B-point.
Inferior airway space (IAS-4): The distance between the posterior pharyngeal wall and the dorsal surface of the base of the tongue measured on the line connecting Go and the B-point.
PNS to tip of the soft palate (PNS-P-6): The length of the line that connects the PNS to the tip of the soft palate. It represents the length of the soft palate.
Mandibular plane to hyoid bone (MP-H): The linear distance along a perpendicular line from the MP to the hyoid bone.
Measurement of TPL: The length from the point P1 at the roof of the pharynx to P4 at the level of C4 (fourth vertebra). This includes the nasopharynx, the oropharynx, and the hypopharynx (Fig. 1).
The medial axis is a line constructed inside the pharynx, calculated geometrically on a graduated scale paper for each patient with each appliance A and B.
A series of horizontal medical axes of the intersection line segment are produced in the middle of the structure equidistant from the outline structure (posterior pharyngeal wall and the dorsal surface of the base of the tongue). The horizontal medial axis points are connected together vertically to produce an intermediate geometrical outline (primary axis). On the primary axis, two points were determined (P1 and P4) and the length of the pharynx (LT) was calculated.
Oxygen saturation (O2), blood pressure, and pulse rate were recorded by pulse oximetry (Fukud Denshi Co. Ltd, Tokyo, Japan). The respiratory disturbance index (RDI) was calculated according to the following formula (number of apnea, hypopnea episodes/h) 16.
The prosthetic construction
For both designs
Maxillary and mandibular master casts were obtained from irreversible hydrocolloid impressions. The hard and soft tissue undercuts were blocked out on these casts and then the casts were duplicated.
Using the Face-Bow, the upper master cast was mounted on a semiadjustable ‘Dentatus’ articulator. Then, the lower master cast was mounted in centric occlusion on the articulator (Fig. 2a).
The patient was instructed to protrude the mandible to the maximal acceptable protrusive position and then a wax bite was obtained (at an increased vertical dimension of 6–7 mm) with a softened wax bite wafer (Fig. 2b).
Cross-mounting of duplicate casts on the articulator was carried out 17.
The design of the appliance (maxillary and mandibular portions) was outlined and waxed on the duplicate upper and lower casts. Full arch occlusal coverage was carried out to tie all the teeth firmly together, extended 3 mm on the buccal surfaces and the incisal edges, and extended onto the soft tissue palatally and lingually.
Jasper Jumper (American Orthodontics, Sheboygan, Wisconsin, USA) (Fig. 3) anterior mandibular position appliance was constructed individually for each patient according to the following procedure:
The maxillary and mandibular cast was covered with a base plate wax. The wax patterns had smooth flat occlusal surfaces. Each one was approximately half the interocclusal space of the increased vertical dimension. Tin foil sheet was used to separate the maxillary and the mandibular wax patterns Interproximal Adam’s wire clasps were adapted to the molar–premolar area for retention (at least two clasps in each side).
Each wax pattern on its duplicate cast was invested and processed in a heat-cured clear acrylic resin (Fig. 4).
Each acrylic portion was fitted to the mounted master casts, the distance from the centric position (0% position) to the maximal acceptable protrusive position (100% position) was measured using a sliding Vernier Caliper (Fig. 5), this distance was divided into 50 and 75%, and lines were drawn on the upper cast at that position.
The acrylic device was fitted to the mounted master casts representing the 75% position line.
Upper and lower acrylic portions were attached together using an intra-arch tube, a rod, and an elastic attachment (Jasper Jumper) (Fig. 6a and b). This attachment allows the jaw to open forward and some side-to-side movements but no retrusive movement. Two Jasper Jumper attachments were used, one on each side.
The patients were instructed to wear the device only at bed time (7–8 h) for 2 months.
A ‘one-piece’ appliance (Fig. 7) was constructed individually for each patient using the following procedure:
The maxillary and mandibular wax patterns that were attached together with a ring hole anteriorly or at any edentulous area were cut through the acrylic for breathing.
Interproximal Adam’s wire clasps or a half-Jackson wrought wire were adapted to the maxillary incisors and the molar–premolar area, respectively.
The wax pattern on its duplicate casts was invested and processed in a heat-cured clear acrylic resin.
The acrylic device was fitted to the mounted master casts in the 75% position.
The patients were instructed to wear the device only at bed time.
The patients were allowed to use their appliances for 2 months; then, the initial preprosthetic follow-up and cephalometric radiographs were traced and superimposed. Linear measurement of the superior, inferior, and middle airway as well as the TPL was carried out in the supine position. The data obtained from cephalometric analysis and medical investigations were collected and compared using a matched-pairs signed-rank test with the comparison of the mean rank of both groups.
Data were analyzed using SPSS 16.0 software (SPSS Inc., Chicago, Illinois, USA). Descriptive statistics such as mean and SD were used. As the SD was considerably high, which indicates high variabilities in measurements, the nonparametric Wilcoxon matched-pairs signed-rank test was used to compare the average preprosthetic and postprosthetic appliance A and appliance B; to study the relation between measurements, Spearman’s rank correlation coefficient was used. The 0.05 level was used as the cut-off value to indicate statistical significance.
Table 1 shows that the mean value of the superior anterior airway linear distance in patients wearing appliance A was 3.80±1.38 mm, whereas that in patients wearing appliance B was 2.30±1.11 mm. Comparison of the mean rank of appliances A and B showed a significant difference at a 0.05 level [matched signed-rank test (MSRT)=2.52].
A statistically significant difference was observed between the preprosthetic mean rank and appliance A (2.80) and the preprosthetic mean rank and appliance B (2.089).
An increase in the mean was observed in the superior anterior airway linear distance when appliance A was worn (3.80) more than that with appliance B (2.30).
Table 2 shows that the mean value of the superior posterior airway linear distance of patients wearing appliance A was 10.54±l.04 mm, whereas the mean value of patients wearing appliance B was 8.79±0.92. A significant difference was observed between appliances A and B at the 0.05 level (2.65).
A statistically significant difference was found between the mean rank of the preprosthetic and appliance A and the preprosthetic and appliance B (2.8 and 2.8) at the 0.05 level. A mean increase was observed in the superior posterior airway space when appliance A was worn.
Table 3 shows that the mean values of the middle airway linear distance of the patients wearing appliances A and B were 13.65±1.43 and 12.5±0.85 mm, respectively, which were significant at the 0.05 level (2.52). Comparison of the preprosthetic and those obtained after the use of appliances A and B revealed a statistically significant difference at the 0.05 level (2.665 and 2.366).
Table 4 shows that the mean values of the inferior airway linear distance of patients wearing appliances A and B were 10.35±3.96 and 11.15±3.83 mm, which were statistically significantly different at the 0.05 level (2.366). Comparison between the preprosthetic mean rank and that after wearing appliance A showed a statistically significant difference (2.803), and no statistically significant change was observed between the preprosthetic mean rank and that after wearing appliance B.
Table 5 shows that the mean values of the TLP with appliances A and B were 8.82±0.52 and 8.92±0.5 mm, which were not statistically significant at the 0.05 level. Comparison of the preprosthetic mean rank and that of appliances A and B showed a statistically significant difference (2.803 and 2.803).
A negative correlation (r) was found as shown in (Table 6) between the superior anterior, posterior, middle, and inferior airway linear distances with the TPL.
Table 7 shows the mean value of the PNS to the tip of the soft palate of patients wearing appliances A and B (41.61±4.86 and 41.61±4.86 mm, respectively). Comparison of the preprosthetic mean rank and that of appliances A and B showed no statistically significant difference.
Table 8 shows the mean value of the MP to the hyoid bone of patients wearing appliances A and B (24.7±2.67 and 25.8±2.66 mm, respectively), which were statistically significant at the 0.05 level (2.084). Comparison of the preprosthetic mean rank and the mean rank and that of appliances A and B showed a statistically significant difference.
Table 9 shows that the mean values of the RDI of patients wearing appliances A and B were 25.48±0.38 and 36.8±1.8 mm, which were significantly decreased at the 0.05 level (2.80). A significant decrease in RDI was found with appliance A. On comparing the percentage decrease in the RDI preprosthetic mean rank and the mean rank of appliances A and B, there was a statistically significant difference (2.80).
Table 10 shows the mean rank of the lowest oxygen saturation of patients wearing appliances A and B (82.0±6.48 and 77.6±6.43 mm, respectively), which was not statistically significant. A significant increase was found when the patient wore appliance A as compared with the preprosthetic mean rank (2.80). A statistically significant difference was found between the preprosthetic mean rank and the mean rank of appliance B (2.803).
Over the past 30 years, knowledge regarding sleep apnea has considerably increased. It is a common disorder and affects men two-fold more than women. The patients selected were men because snoring is common in men; the exact reason for this is unknown 18,19. A possible explanation could be hormonal influences affecting the upper airway muscles and the difference in the pharyngeal anatomy and functions.
The preprosthetic and postprosthetic measurements of cephalometric radiographs were taken in the supine position with the Frankfurt plane at a right angle to the floor 13,15.
This was postulated by Pae et al. 15, who concluded that the upper airway obstruction during sleep usually occurs in the supine position; these changes might be mainly because of the physiologic response to the respiratory load and narrowed upper airway. However, Naughton 20 concluded that apnea occurs in the supine position, which is similar to a patient’s position during sleep, which results in a large negative intrathoracic pressure, creating a vacuum-like pressure around the heart that could lead to left ventricular hypertrophy, pulmonary edema, left heart failure, and gastroesophageal reflux. Also, the pharyngeal structures are supported by various oropharyngeal muscles and insufficient muscle tonic activity against this intraluminal negative pressure and gravity might be significant contributing factors in the development of a narrow pharynx 20.
Cephalometric radiographs represent a conventional simple technique and are an accessible screening tool used to measure the upper airway patency 15.
Most of the treatment modalities of sleep apnea are focused on widening the constricted part of the pharynx (oropharyngeal). An effective simple, inexpensive treatment is available such as CPAP, which has been shown to improve quality of life, but the most common problem with CPAP is nasal irritation and a dry mouth (because of excessive pressure). Also, surgery and removable intraoral appliances are used to treat sleep apnea 21,22.
In this study, a Jasper Jumper appliance and a one-piece appliance were used. These types of conservative treatment modalities would be beneficial for patients who are at poor surgical risk, do not wish to undergo surgery, or those who have not responded adequately to surgical procedures. Also, these appliances are comfortable, easily accepted, noninvasive, and cost-effective 22.
The significant increase in the superior (posterior and anterior), middle, and inferior airway linear distance with appliances A and B might be because of the reduction in apneic episodes in the patient because the mandible and the tongue are maintained in a stable anterior position, thus preventing posterior relapse of the mandible and tongue during sleep. As the mandible opens, the tongue is carried downwards and the soft palate moves forward (this is evident from the superior posterior airway). This allows a large lumen for air to pass through during inspiration, thereby decreasing the likelihood of an obstructive event 23.
Before the insertion of the appliances, apneic patients showed considerably higher elongation of the pharyngeal length. Pae et al. 15 concluded that apneic patients also have less efficient genioglossus muscles.
Rider 24 revealed that the genioglossus muscle relaxes substantially during REM sleep, allowing the tongue to fall back further into an already constricted hypopharyngeal space. This genioglossus muscle activity is important to keep the upper airway patent more in the supine than in the upright position and the pharynx becomes longer in apneic patients when they change the body position from an upright to a supine position. The longer the pharynx, the more severe the symptoms. There is no significant correlation between the width of the pharynx (airway linear distance) and the pharyngeal length, as the air in the larynx–pharynx travels faster than air in a shorter one, because the same volume of tidal air must pass through each conduit during the same respiration duration; therefore, the velocity of air in the longer pharynx is greater than that in the short pharynx, and this faster air stream in the longer pharynx generates more negative intraluminal pressure and leads to more collapse in the longer pharynx 15.
When the patients wore appliances A and B, they showed a significant decrease in the pharyngeal length, forward movement of the tongue, and an increase in the oropharyngeal airway space, with less oropharyngeal tissue collapse with negative inspiratory pressure. This is a good indicator of the success of the appliance in improving sleep apnea. The insignificant change in the soft palatal length (PNS-soft palate) can be attributed to the change in position, shape, and function of the soft palate as a result of the mandibular advancement 20. The hyoid bone anchors the musculature of the tongue and represents the inferior part of the tongue; thus, the significant decrease in MP to the hyoid might be because of the downward and forward slope of the MP 25.
The altered anatomical relationships induced by both appliances A and B might be attributed to the condylar translation through the forward position of the mandible and the tongue may have induced neurosensory stimulation that influenced the motor tone and the collapsibility of airway, which improved the RDI and the oxygen saturation during sleep through the large lumen for air to pass 13,23.
From this study, we conclude as follows:
Anterior mandibular positioning appliances – either Jasper Jumper or one-piece, are successful conservative treatment appliances for the prevention of sleep apnea.
Both appliances exert a therapeutic effect by improving the respiratory disturbances that occur during sleep and by enhancing the anatomical relationship of the upper airway space.
Both the dentist and the patient must be aware of the deleterious side effects of micrognathia, retrognathia, and a narrowed mandibular arch on respiration during sleep.
\The team for the management of sleep apnea currently includes not only an otolaryngologist, a pulmonologist, a neurologist, and a sleep laboratory clinician but also prosthodontists and orthodontists.
No fund from any source were used for this study. All work was done in the Oral and Maxillofacial Rehabilitation Department, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia. My thanks are dedicated to Professor Dr. Mona Hassan, Professor of statistical. I wish to express my deepest gratitude to all those who assisted us to complete this work.
Conflicts of interest
There are no conflicts of interest.