| Abstract|| |
Obstructive sleep apnea (OSA) is one of the most common forms of sleep-disordered breathing. Various treatment modalities include behavior modification therapy, nasal continuous positive airway pressure (CPAP), oral appliance therapy, and various surgical modalities. Oral appliances are noninvasive and recommended treatment modality for snoring, mild to moderate OSA cases and severe OSA cases when patient is not compliant to CPAP therapy and unwilling for surgery. Acoustic reflection technique (ART) is a relatively new modality for three-dimensional assessment of airway caliber in various clinical situations. The accuracy and reproducibility of acoustic rhinometry and acoustic pharyngometry assessment are comparable to computerized tomography and magnetic resonance imaging. This case report highlights the therapeutic efficacy of an innovative customized acrylic hybrid mandibular advancement device in the management of polysomnography diagnosed OSA cases, and the treatment results were assessed by ART.
Keywords: Acoustic pharyngometry, acoustic rhinometry, mandibular advancement device, obstructive sleep apnea
|How to cite this article:|
Agarwal S S, Jayan B, Kumar S. Therapeutic efficacy of a hybrid mandibular advancement device in the management of obstructive sleep apnea assessed with acoustic reflection technique. Indian J Dent Res 2015;26:86-9
Obstructive sleep apnea (OSA) is one of the most common forms of sleep-disordered breathing (SDB) affecting more than 4% of the adult population.  It is often associated with co-morbidities such as hypertension, hyperlipidemia, hypoglycemia, excessive daytime sleepiness, behavioral changes and poor work performance.  Polysomnography (PSG) is the current gold standard to diagnose, and nasal continuous positive airway pressure (CPAP) is the gold standard to treat OSA patients with long-term compliance of CPAP between 50-80%.  Oral appliances are noninvasive and recommended treatment modality for snoring, mild to moderate OSA cases and severe OSA cases when patient is not compliant to CPAP therapy and not willing for surgical modalities. ,
|How to cite this URL:|
Agarwal S S, Jayan B, Kumar S. Therapeutic efficacy of a hybrid mandibular advancement device in the management of obstructive sleep apnea assessed with acoustic reflection technique. Indian J Dent Res [serial online] 2015 [cited 2020 Jul 6];26:86-9. Available from: http://www.ijdr.in/text.asp?2015/26/1/86/156820
Acoustic reflection technique (ART) is a relatively new modality for three-dimensional assessment of airway caliber in various clinical situations. It was first introduced  in 1977 and since then, it is increasingly used to evaluate pharyngeal airway in SDB. The accuracy and reproducibility of acoustic rhinometry (AR) and acoustic pharyngometry (AP) assessment is comparable to computerized tomography (CT) and magnetic resonance imaging. , This case report highlights the therapeutic efficacy of an innovative customized acrylic hybrid mandibular advancement device (MAD) in the management of OSA cases and the treatment results were assessed by ART.
| Case report|| |
A 52-year-old male was referred by department of Pulmonary and Sleep Medicine for craniofacial evaluation and feasibility of oral appliance therapy as the patient was not willing for CPAP therapy. He reported with complaints of excessive snoring and daytime sleepiness, feeling of congestion during sleep, frequent headaches, and lack of concentration at work. His PSG revealed an apnea-hypopnea index (AHI) of 19.7 events per hour which indicated moderate OSA. His body mass index was 30, and Epworth Sleepiness Scale (ESS) was 20. His airway grading was modified Mallampatti Score III. Tongue position was lowered. He had a sound dentition with missing 13 and a poor oral hygiene.
Lateral cephalogram [Figure 1] revealed Class II skeletal bases (ANB 6°) with decreased superior airway space (SAS = 10 mm), posterior airway space (PAS = 7 mm) and minimum airway space (MAS = 7 mm). Hyoid distance was increased (26 mm) [Table 1]. AP findings [Figure 2] revealed that mean pharyngeal area (MPA) was 3.04 cm 2 against the norms  of >3.2 cm 2 , minimum pharyngeal area (MIPA) was 1.61 cm 2 against the norms  of >2.0 cm 2 and pharyngeal airway volume (PAV) was 30.41 cm 3 . AR examination of the right nostril [Figure 3] revealed that nasal airway resistance (NAR) was 0.72 cm H 2 O/L/Min and nasal airway volume (NAV) was 24 CC. AR examination of the left nostril [Figure 4] revealed that NAR was 0.58 cm H2 O/L/Min, and NAV was 24.01 cm 3 . He was planned to be treated with a customized hybrid MAD incorporating provision for nasal airway dilatation and tongue repositioning along with an increase in pharyngeal airway caliber.
Fabrication of the appliance
Maximum protrusion of the patient was determined clinically (7 mm) and airway metric gauges [Figure 5] were used to simulate the desired mandibular advancement in both sagittal and vertical dimensions which would provide an optimum increase in airway caliber and this was confirmed by repeat AP examination and titration was done until desired increase in airway caliber was achieved. This predetermined mandibular position (i.e., at 4 mm advancement which was approximately 60% of maximum protrusion) was then recorded with a customized acrylic bite gauge using an elastomeric impression compound [Figure 6]. The working model along with a bite was articulated. Durasoft 2.5 mm thermoplastic sheet was adapted on working model. A 19 gauge stainless steel wire was used to make four wire segments (approximately 2 cm in length) with a 1 mm diameter loop at its end over which round acrylic buttons (2 mm diameter) were fabricated. Self-cure acrylic was then adapted over the durasoft sheet in a uniform layer and two wire segments were integrated vertically in the upper lateral incisor-canine region (nasal airway expanders) and two in the lower second premolar region lingually and horizontally (tongue repositioners). A 0.5 cm diameter hole was made in the anterior region to prevent suffocation especially in the first few days, and this hole can be gradually closed [Figure 7]. This appliance also acts as an oral screen for habit breaking in those OSA patients which are mouth breathers also. The appliance was then finished, polished, and delivered. The patient was asked to wear it initially for a few hours during sleep and gradually increase the wearing time to overnight.
| Results|| |
Significant symptomatic improvement was noted in follow-up appointments. Investigations were done after 2 months with appliance in situ. PSG revealed that his AHI decreased from 19.7 to 9.2 events per hour (more than 50% reduction in AHI) along with gross reduction in total number of apneic and hypopneic events. ESS reduced from 20 to 3. Lateral cephalogram [Figure 8] revealed that SAS, PAS, and MAS with appliance in situ increased to 14, 12, 11, respectively, and hyoid distance reduced to 14 mm [Table 1]. AP examination revealed 25.7% increase in MPA, 42.9% increase in MIPA and 25.7% increase in PAV [Figure 2]. These findings were in concordance with the cephalometric and PSG findings. AR examination of the right nostril [Figure 3] revealed 6.9% decrease in NAR and 21.2% increase in NAV. AR examination of the left nostril [Figure 4] revealed that NAV increased by 10.7%. However, NAR did not show a significant change in the left nostril.
| Discussion|| |
Various treatment modalities for the management of OSA are behavior modification (e.g., weight reduction, regular exercises, and limiting alcohol consumption), nasal CPAP, oral appliances, and surgical modalities (e.g., maxillomandibular advancement, transverse maxillary expansion etc). , Oral appliances improve upper airway configuration and prevent its collapse by enlarging the pharyngeal airway passages during tongue/mandibular anterior repositioning and thereby causing a decrease in airflow resistance. , Brown et al. in their study observed that mandibular advancement increases airway size as the entire tongue moves forward. Lateral airway expansion is also produced during mandibular advancement via a direct connection between the lateral walls and the ramus of the mandible.  The present case was a PSG diagnosed case of moderate OSA (AHI 19.7 events per hour) who was non-compliant to CPAP therapy. He had class II skeletal bases (ANB = 6°), reduced pharyngeal airway dimensions and increased NAR as revealed by the cephalometric analysis and ART assessment. Hence, as per the practice parameters for the treatment of snoring and OSA,  he was an appropriate candidate for oral appliance therapy. Further candidacy was established by AP examination by predicting the increase in airway caliber which can be achieved by the oral appliance therapy. In addition, he had a lowered tongue posture which was also responsible for pharyngeal obstruction. Keeping all these factors in mind, a customized MAD was fabricated which also incorporated nasal airway expansion pads (to dilate nasal airway) and tongue repositioners (for superior repositioning of tongue). The appliance was made in self-cure acrylic which made it a highly economic alternative which can be used in public health set-ups. A similar appliance was designed by Mark Abramson and named Oral nasal Airway System and approved by FDI in 2004 to simultaneously dilate the nasal passages and reposition the mandible forward. It is a titratable appliance which permits some lateral mobility of the mandible, but our appliance is a non titratable appliance since the desired mandibular position was predetermined by AP technique and needs minimal future corrections. Furthermore, upper and lower splints are joined together in our appliance whereas the upper splint can be completely detached in their appliance. In addition, we have incorporated a hole in the center of the appliance to prevent suffocation especially in initial few days of appliance wear. Other FDI approved oral appliances are Thornton adjustable positioner, somnomed, nocturnal airway dilator, etc. 
Follow-up investigations usually include a lateral cephalogram and PSG with appliance in situ. In our case follow-up lateral cephalogram revealed increased SAS, PAS, and MAS and reduced hyoid bone distance. PSG revealed AHI of 9.2 events per hour, that is, more than 50% reduction in AHI was achieved along with symptomatic improvement in the patient. In addition, in our case, we have used ART examination to assess the changes in pharyngeal and nasal airway dimensions as well as to monitor changes in NAR. AP revealed an increase in PAV, MPA, and MIPA whereas AR showed increased NAV and decreased NAR in both right and left nostrils.
| Conclusion|| |
- Oral appliance therapy should be tailored based on the severity of OSA, patient compliance, and dento-craniofacial causative factors
- The present oral appliance system is an effective modality in mild to moderate OSA cases that are non-compliant to CPAP therapy
- Being a cheaper alternative, it can be used effectively in public health care set-ups.
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S S Agarwal
Department of Orthodontics and Dentofacial Orthopedics, Armed Forces Medical College, Pune, Maharashtra
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]