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October's Tip: The Effects of Mandibular Position on Airway and TMD: A Case Report

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By: Dr. Keri Do


Comprehensive orthodontics is a treatment that needs to target and correct issues beyond malocclusions, such as teeth alignment or damaging overbites. It can affect comprehensive factors that require a multidisciplinary approach such as alignment of the TMJ, opening of the respiratory passage or airway, leveling of the occlusal plane, and stabilization of the occlusion, subsequently creating beautiful smiles and faces. In addition, an important development of treatment that should not be overlooked is the patency of an airway. The position of the mandible can contribute to how much an airway is open or closed. For example, when the mandible is more retruded, which can occur when changing from an upright to a supine position, the airway passage will narrow. (1) A retruded mandible position can also negatively affect the TMJ. Joint derangement has been shown to have a direct correlation with the amount of mandibular retrusion. (2) Treatment goals should include positioning the mandible in the correct condylar position and functional airway position and subsequently moving the teeth to support that position. (3-5) This clinical report illustrates cases where the patient was treated for TMD and obstructive sleep apnea with functional appliances and orthodontics.

Case 1 - Diagnosis:

A 48-year-old female patient presented for a routine dental check-up. Upon visual examination, the patient's occlusion and teeth appeared well-aligned (Figure 1). However, during her medical and dental history evaluation, the patient seemed to exhibit symptoms of TMD and obstructive sleep apnea. The patient stated she had head and neck pain every other day with headaches that seemed to occur randomly throughout the day but always became worse when she ate. The patient also complained of dizziness, ringing in her ear on the right side, ear stuffiness, loss of hearing, neck pain, and clicking in her jaw. In addition, the patient stated that she felt constantly tired and was out of breath when doing certain activities. The patient was medically diagnosed with asthma and shortness of breath. Her physician recently prescribed medications for her including fexofenadine (allergy), Advair (asthma), Nexium (gastric reflux), and Nasonex (nasal allergy).

Her dental history included 4 years of orthodontic treatment about 20 years ago. It was at this time that her two maxillary first bicuspids were extracted. This treatment left her with some resorbed roots on her remaining upper bicuspids (Figure 2) and a molar class II relationship (Figure 1). Her upper and lower anterior teeth had mild crowding. Her upper occlusal plane did not align with her lower plane (Figure 3). Her skeletal midline was deviated to the right side by 2mm. Her maximum opening was 35mm. She had missing upper bicuspids, a retruded mandible, and a lower lingual tori where the left side was larger than the right, caused by an inbalance in occlusal contacts (Figure 4). These symptoms indicated signs of

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teeth clenching. Her periodontal exam revealed some localized bone loss distal of the upper left bicuspid #13. The patient had a moderate amount of tetracycline staining.

Her TMJ exam demonstrated "clicking" on the right joint on opening. Cone beam CT (CBCT) displayed asymmetric joint spaces and asymmetric condylar shape with wear on the right condyle (Figure 5). Sassouni plus cephalometric analysis showed a lingually-positioned upper incisor angle, an ANS posterior to the anterior arc, a retruded mandible position, and a high gonial angle posterior to the posterior arc. Sassouni plus analysis showed that the patient had a high risk for developing TMD (6) and was prone to developing obstructive sleep apnea (OSA). (7) The analysis also revealed a class II skeletal open bite with the position of the menton below the lowest vertical arc (Figure 6). Soft tissue evaluation revealed a flat and low upper lip angle. A lateral cephalometric x-ray also revealed a very constricted airway (Figure 7).


Treatment objectives included alleviating the patient's craniofacial pain and opening up the airway. This was achieved by positioning the mandible to where the condyles were centered on the disc. This location subsequently provided an increase in the airway passage. Cone beam computed tomography- CBCT of both TMJ was taken to check the initial bite position. The mandible was then placed in the correct condylar position with orthotic splints (8) and verified with CBCT. One splint was worn during the day while another was worn at night. (4) Her symptoms started to improve once she wore her splints as directed. The patient filled out a TMD progress report at each visit. Based on her TMD symptoms, the patient wore the splints for approximately 3 months. The following treatment included a maxillary 4-screw removable appliance which was used to develop both arch length and width. (4,9) The patient wore the appliance until enough spaces were created to accommodate the forwarded mandible, and she was then placed on straight wire orthodontics to align and consolidate the teeth in addition to creating spaces for the missing upper bicuspids. The upper and lower occlusal planes were also leveled and aligned (Figure 8), the molars and canines were re-positioned from a class II to class I bite, and the skeletal midline was aligned.


At the end of treatment, the patient reported experiencing better sleep and with near elimination of craniofacial pain. The patient reported not needing to take some of her medications for asthma since there was improvement in her breathing and sleep quality. The maxillary arch expansion and protraction created spaces for the upper bicuspids (Figure 9). The occlusal planes were level and aligned (Figure 8). Based on a Sassouni Plus analysis, the posterior portion of the mandible moved forward in relation to the posterior arc, pogonion to ANS arc value increased by 5.5, B to A point arc increased to 2.1, and mention position was closer to the lowest vertical arc. The airway increased with the mandible moving forward to a class I skeletal position (Figure 10). CBCT showed increased posterior joint spaces (Figure 11). The patients' final retention was obtained

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with an upper Essix appliance against a lower sleep apnea appliance to maintain the open airway at night.

Case 2 - Diagnosis:

A 15-year-old male presented for orthodontic treatment. Medical history revealed no significant findings. Dental history revealed that the patient had a treatment plan for serial extractions from his previous dentist. The patient had missing upper bicuspids with closure of extractions sites. He was a class III molar malocclusion with anterior edge-to-edge bite. The patient had severe lower arch crowding with cross bite on both lower canines and lower left 1st bicuspid (Figure 12). His upper arch size was considerably smaller than the lower arch. Cone beam computed tomography (CBCT) of the TMJ reveal symmetrical constricted joint spaces (Figure 13). However, the patient exhibited no TMD symptoms or craniofacial pain. Lateral cephalometric revealed a moderate localized constricted airway.

Treatment and Result:

Treatment objectives included increasing upper arch size, increasing the airway, and leveling and aligning upper and lower teeth. The patient was started on an upper removable expansion appliance followed by straight wire treatment to create space for the missing bicuspids and to increase arch size. Treatment resulted in a class I molar occlusion and correction of the anterior crossbite (Figure 14). The occlusal planes were level and teeth aligned. The spaces were created to allow for replacement of the upper bicuspids. The temporal mandibular joints were aligned with an increase in posterior joint space (Figure 15). There was an increase in both the upper and lower arch size which resulted in more room for the tongue and a large increase in the size of the airway passage (Figure 16).


These cases illustrate that we must look beyond teeth alignment and overbite corrections when performing orthodontic treatment. Upper bicuspid extractions are a common method of camouflaging skeletal class II conditions and can possibly influence other oral-facial structures. These patients had a class II overbite which was treated with upper bicuspid extractions from prior orthodontics. As a result, this reduced the size of the maxillary arch, which trapped the mandible and constricted the airway. Measurements for the size of the maxilla and the size of the dental arches have a direct influence on the upper airway. (10) When the maxillary arch is constricted, the patient is predisposed to the development of OSA, (11) because OSA patients have been shown to have a narrower and shorter maxillary arch than non-OSA patients. (17) Therefore, we expanded the maxillary arch sagittally and horizontally with a functional appliance. A protraction appliance of the maxillary arch can increase the size of the airway. (13) Likewise, arch expansion can increase nasal volume (14) and reduce the incidence of OSA. (15) Other studies also show that rapid expansion of the upper arch reduces the severity of OSA. (16)16 Another study with twin block therapy illustrates that repositioning the mandible contributes to an increase in vertical dimension which consequently led to an increase in airway. (17)

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A trapped and more posteriorly-positioned mandible predisposes the patient to TMD, often leading to joint derangement. (18, 19) These TMD symptoms often include headaches or migraines, ear stuffiness, tinnitus (ringing in the ears), clicking of the joints, neck pain, joint sounds, and joint pain. (20) One major finding common in patients diagnosed with TMD is that the mandible is positioned too posteriorly. This posterior displacement of the condyles has been shown to develop disk displacement, clicking, muscle spasm, pain, and remodeling of the joint. (21) Another unusual symptom which might be attributed to other causes is ringing in the ears (tinnitus). Tinnitus patients also have frequent headaches and fatigue/tenderness in jaw muscles. (22) This interrelates with mandibular retrusion and subsequently TMD. We treated the patient by repositioning the mandible forward to recapture the dislocated disk. (23) With splint treatment, the condyles are positioned to remodel at this bite and the teeth to function at the planned new occlusion. (24) The teeth were then moved into this new position with orthodontics, increasing the patients' airway. The airway is further increased and maintained with a nighttime mandibular repositioning appliance.


The patient's airway and TMJ are two significant factors that must be considered when treating any type of orthodontics. Comprehensive treatment starts when the TMJ and airway are properly evaluated and addressed when diagnosing long­term care. Orthodontic treatment is analogous to full mouth reconstruction but with natural teeth. The position in which teeth are moved determines the bite with which the patient will function daily for the rest of his or her life. We know that we need to treat the patient to a functional bite and hopefully be devoid of any future problems relating to initial treatment. We also must make sure that the position where the teeth are moved will support a healthy joint and maintain a patent respiratory passage or airway.

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