Temporomandibular Joint Disk Displacements in Class II Malocclusion and Cervical Spine Alterations: Systematic Review and Report of a Hypodivergent Case with MRI Bone and Soft Tissue Changes

(1) Background: This study aimed to perform a literature review related to disk displacement (DD) in class II malocclusion or cervical vertebrae position alterations and to report a hypodivergent case with cervical pain and right anterolateral DD with reduction, left anterolateral DD with reduction, and left joint effusion. (2) Methods: A structured electronic search was conducted between March 2022 and April 2022, without time limits, following PRISMA guidelines, in the following databases: PubMed, Scopus, Embase and Cochrane; the terms “disc displacement”, “disk displacement”, “temporomandibular joint”, “class II malocclusion” and “cervical vertebrae” are searched. (3) Results: the following thirteen publications are included in this review: two prospective studies and eleven cross-sectional studies; for evaluating disk position, eight included publications used magnetic resonance imaging (MRI), whilst six studies used lateral cephalogram to determine craniofacial morphology and relationships between the cranial base, vertical skeletal pattern, maxilla and mandible. (4) Conclusions: although the literature still shows contradictory opinions, a relationship between temporomandibular disorders and cervical posture has been shown in the presented case as well as in the literature review.


Introduction
The functionality of the face and of the human body is dependent on the temporomandibular joints (TMJs) and their accompanying tissues [1]. Due to the multifactorial etiology and the high prevalence of temporomandibular disorders (TMDs), there is a continuous need for a redesigned, patient-centered, interprofessional approach to TMD treatment and prevention [2]. TMD refers to a series of musculoskeletal conditions that affect the TMJ, the masticatory muscles, as well as other tissues [3]. TMD is characterized by pain, joint noises, jaw movement limitation, muscle discomfort or joint sensitivity [4]. Clinical diagnosis of TMD is performed according to the Axis I of the Research Diagnostic Criteria for TMD (RDC/TMD), which validates the pain-related TMDs and the intra-articular disorders [4,5]. The definition of TMD kept on expanding, such as a workgroup formed by participants from various research fields, such as the American Academy of Orofacial Pain, the European Academy of Craniomandibular Disorders, the Australian and New Zealand Academy of Orofacial Pain, the International Headache Society, the Orofacial Pain SIG of the International Association for the Study of Pain, the International RDC/TMD

Description of the Studies and Analysis
The following data was extracted from the following articles: (1) authors and year of publication; (2) type of publication; (3) number of studied subjects; (4) mean age of subjects; (4) TMD diagnostic method; (5) outcome; (6) author's conclusion.
The main characteristics of the studies that were considered in this review are summarized in Table 1.

Description of the Studies and Analysis
The following data was extracted from the following articles: (1) authors and year of publication; (2) type of publication; (3) number of studied subjects; (4) mean age of subjects; (4) TMD diagnostic method; (5) outcome; (6) author's conclusion.  to determine the association between the progression of ID and alteration in the dentofacial morphology − decrease in posterior facial height, a decrease in ramus height, and backward rotation and retruded position of the mandible in the subjects with ID of the TMJ "lower posterior facial height and ramus height, backward rotation of ramus and mandible, and relative protrusion of upper and lower lips were found in the patients with ID of the TMJ. These changes became increasingly severe as ID progressed to DDwR ID of the TMJ might induce dentofacial changes" − reduced plane atlas angle in TMD (which verifies the craniocervical posture) suggesting a suggests a flexion of the first cervical vertebra − increased anterior translation distance in TMD, showing an anteriorization of the cervical spine "the symptomatic TMD patients presented a flexion of the first cervical vertebra associated with an anteriorization of the cervical spine (hyperlordosis)" "subjects with symptomatic TMD had a tendency to present flexion of the first cervical vertebra and an anteriorization (hyperlordosis) of the cervical spine (C2-C7)" to evaluate the possibility of any correlation between DD and parameters used for evaluation of skull positioning in relation to the cervical spine: craniocervical angle, suboccipital space between C0-C1, cervical curvature and position of the hyoid bone − differences were observed between C0-C1 measurement for both symptomatic and asymptomatic − no association between craniocervical angle, C1-C2 and hyoid bone position in relation to DD "no direct relationship could be determined between the presence of DD and the assessed variables" "there is a close anatomofunctional relationship between the masticatory system and the cervical region and scapular centric" "the postural alteration of the head leads to a disadvantage to muscular biomechanics" "the relationship between craniocervical disorder and TMD may be related to the muscular component rather than the articular one" "there is a significant association between TMD treatment and reduction of cervical spine pain, as far as improvement of cervical spine mobility" PT-publication type; CS-cross-sectional; PS-prospective study; MRI-magnetic resonance imaging; DDR-disk displacement with reduction; DDwR-disk displacement without reduction; N-normal disk position, TMJ-temporomandibular joint; DD-disk displacement; ID-internal derangement; CVT/EVT-cervical lordosis angle; RDC/TMD-research diagnostic criteria for temporomandibular disorders; ROM-range of movement; VAS-visual analogue scale; ARS-anterior repositioning splint.

Case Report
A thirty-nine-year-old Caucasian female patient presented for treatment with a chief complaint of temporomandibular disorder, associated with headaches and neck and shoulder pain, with a duration of more than six months.
The patient had a history of car collisions thirty-one years prior, in which she suffered multiple traumas, including cranial bone fissures (left temporal and occipital region). She also reported teeth clenching and night bruxism for more than ten years and overthe-counter medication used for headaches and muscle tenderness. The patient was also diagnosed with chronic rhinitis and bilateral chronic maxillary sinusitis by an otorhinolaryngologist, who preliminarily diagnosed fibromyalgia and TMD as well; therefore, she was referred to an orthodontist for evaluation and treatment.
The subsequent clinical examination was performed by both an orthodontist and a TMD specialist, with over twenty years of experience. During history taking, the patient also revealed pain in the right temporomandibular area with TMJ clicking and popping and uncomfortable jaw motions. The patient also reported right throat soreness and neck, shoulder and back pain. She also mentioned associated tinnitus in the right ear.
After filling out the Kinnie-Funt Chief Complaint Visual Index for Head, Neck and Facial Pain and TMJ dysfunction [35,36], we found that she ranked the following as her top three complaints: right sore throat without infection; "migraine"-type headache; tired, sore, neck muscles. The patient also noted additional complaints such as the following: inability to open the mouth smoothly and evenly; clicking, popping temporomandibular joints, pain in jaw muscles, balance problems ("vertigo"), ear pain without infection, upper and lower back pain. Neck pain was rated 7/10 on a VAS pain scale [37].
After performing a clinical examination, RDC/TMD criteria indicated a clinical diagnosis of bilateral disk displacement with a reduction [4,38].
The patient was referred to perform a lateral cephalogram along with magnetic resonance imaging (MRI) of the temporomandibular joints.
The lateral cephalogram showed a hypodivergent class II skeletal pattern, with a small anterior facial height, skeletal deep bite tendency and normal overbite and overjet ( Table 2).  The lateral cephalogram of the patient is shown in Figure 2.
position of the maxilla); SNB-angle between Sella-Nasion-B point (sagittal position of the mandible); FMA-angle between orbitale to porion and point A (Frankfort-mandibular plane angle: facial pattern); Gn-gnathion (the most outward point on the curvature of the symphysis of the mandible); Go-gonion (angles of the mandible); Y axis-the line connecting Sella to Gnathion; Me-menton (the lowest point on the symphysis of the mandible); lower anterior facial height: a line between anterior nasal spine and Me; Wits appraisal-difference between perpendiculars from points A and B onto the occlusal plane; SD-standard deviation.
The lateral cephalogram of the patient is shown in Figure 2. The craniocervical posture was evaluated by performing the Rocabado analysis [39]. In the following, we evaluated: the craniovertebral angle, the hyoid bone position, and the main vertebrae distances. The distance between cervical vertebrae was evaluated as follows: suboccipital space (the distance from the occiput to the first cervical vertebra; cranium-atlas distance, C0-C1), atlas-axis distance (C1-C2), the distance between the axis and third vertebrae (C2-C3). The following values were found: hyoid bone position of 25.9 mm, craniovertebral angle of 100°, and occipital-atlas angle of 6.1°, and for the following vertebrae distances: C0-C1: 6.27 mm, C1-C2: 5.85 mm, C2-C3: 3.98 mm (Figure 3). The craniocervical posture was evaluated by performing the Rocabado analysis [39]. In the following, we evaluated: the craniovertebral angle, the hyoid bone position, and the main vertebrae distances. The distance between cervical vertebrae was evaluated as follows: suboccipital space (the distance from the occiput to the first cervical vertebra; craniumatlas distance, C0-C1), atlas-axis distance (C1-C2), the distance between the axis and third vertebrae (C2-C3). The following values were found: hyoid bone position of 25.9 mm, craniovertebral angle of 100 • , and occipital-atlas angle of 6.1 • , and for the following vertebrae distances: C0-C1: 6.27 mm, C1-C2: 5.85 mm, C2-C3: 3.98 mm (Figure 3).  The Rocabado analysis showed a modified hyoid bone position as well as decreased space between C1-C2 and C2-C3 vertebrae; moreover, the C2 vertebrae showed a rotation and the cervical spine had a vertical orientation.
On sagittal proton density MRI of the right joint, in an open mouth position, the posterior border of the distal band was positioned anteriorly to the posterior slope of the articular eminence and the head of the condyle, indicating an anterior disk displacement (DD). In the closed moth position, the disk was centered over the condyle, showing a disk displacement with reduction (DDR, Figure 4). The Rocabado analysis showed a modified hyoid bone position as well as decreased space between C1-C2 and C2-C3 vertebrae; moreover, the C2 vertebrae showed a rotation and the cervical spine had a vertical orientation.
On sagittal proton density MRI of the right joint, in an open mouth position, the posterior border of the distal band was positioned anteriorly to the posterior slope of the articular eminence and the head of the condyle, indicating an anterior disk displacement (DD). In the closed moth position, the disk was centered over the condyle, showing a disk displacement with reduction (DDR, Figure 4).
Sagittal proton density MRI of the left joint showed in an open mouth position an anterior disk displacement (DD). In the closed moth position, the disk was recaptured, showing a disk displacement with reduction (DDR, Figure 5). Bone changes of the left condyle were found; a flattened condyle with posterolateral compression of the left condylar head and lateral resorption with posterior positioning of the condyle in the articular fossa. A thickened posterior band disk shape was also noted.
In coronal MRI sequences, the right and left disk were found to be laterally displaced, as shown in Figure 6.
In sagittal T2 weight images, left joint effusion was found, as being an increased signal intensity in the joint space (Figure 7). The Rocabado analysis showed a modified hyoid bone position as well as decreased space between C1-C2 and C2-C3 vertebrae; moreover, the C2 vertebrae showed a rotation and the cervical spine had a vertical orientation.
On sagittal proton density MRI of the right joint, in an open mouth position, the posterior border of the distal band was positioned anteriorly to the posterior slope of the articular eminence and the head of the condyle, indicating an anterior disk displacement (DD). In the closed moth position, the disk was centered over the condyle, showing a disk displacement with reduction (DDR, Figure 4).   showing a disk displacement with reduction (DDR, Figure 5). Bone changes of the left condyle were found; a flattened condyle with posterolateral compression of the left condylar head and lateral resorption with posterior positioning of the condyle in the articular fossa. A thickened posterior band disk shape was also noted. In coronal MRI sequences, the right and left disk were found to be laterally displaced, as shown in Figure 6.  In coronal MRI sequences, the right and left disk were found to be laterally displaced, as shown in Figure 6. In sagittal T2 weight images, left joint effusion was found, as being an increased signal intensity in the joint space. (Figure 7). Based on the MRI examination, a diagnosis of right lateral disk displacement with reduction and left anterolateral disk displacement with reduction and left joint effusion was established.

Discussion
In this review were included a number of thirteen articles. Among these, two were prospective studies and eleven were cross-sectional studies.
A number of 1612 subjects resulting from the thirteen selected publications were included in this review. The majority of publications included young adult subjects, with ages ranging between 18 and 40 years; just a single study included young juvenile class II patients with anterior DDR [32]. Six of the studies included a control group and a study group. Most studies used the lateral cephalogram to determine the skeletal pattern [14,24,30,31,33].
Due to its excellent diagnostic accuracy, MRI is the gold standard in identifying TMJ disc position related to the condyle and articular eminence [40]. MRI investigation is also the standard reference in the diagnosis of inflammatory diseases of the TMJ [41] and can be also used for evaluating TMJ bone alterations [42]. For evaluating disk position, a number of eight included studies in this review used MRI images [14,24,26,[29][30][31][32][33].
A number of six studies used lateral cephalogram to determine craniofacial morphology as well as relationships between the cranial base, vertical skeletal, maxillary and mandibular dental and soft tissue [14,17,24,26,30,31].
Flores et al. used lateral skull and cervical teleradiography for performing cephalometric measurements. Along with morphometric variables, the authors evaluated the posterior-inferior angle, atlanto-occipital functional space, hyoid triangle and depth of the cervical skull curvature [28]. The authors concluded that there is a link between morpho- Based on the MRI examination, a diagnosis of right lateral disk displacement with reduction and left anterolateral disk displacement with reduction and left joint effusion was established.

Discussion
In this review were included a number of thirteen articles. Among these, two were prospective studies and eleven were cross-sectional studies.
A number of 1612 subjects resulting from the thirteen selected publications were included in this review. The majority of publications included young adult subjects, with ages ranging between 18 and 40 years; just a single study included young juvenile class II patients with anterior DDR [32]. Six of the studies included a control group and a study group. Most studies used the lateral cephalogram to determine the skeletal pattern [14,24,30,31,33].
Due to its excellent diagnostic accuracy, MRI is the gold standard in identifying TMJ disc position related to the condyle and articular eminence [40]. MRI investigation is also the standard reference in the diagnosis of inflammatory diseases of the TMJ [41] and can be also used for evaluating TMJ bone alterations [42]. For evaluating disk position, a number of eight included studies in this review used MRI images [14,24,26,[29][30][31][32][33].
A number of six studies used lateral cephalogram to determine craniofacial morphology as well as relationships between the cranial base, vertical skeletal, maxillary and mandibular dental and soft tissue [14,17,24,26,30,31]. Flores et al. used lateral skull and cervical teleradiography for performing cephalometric measurements. Along with morphometric variables, the authors evaluated the posterior-inferior angle, atlanto-occipital functional space, hyoid triangle and depth of the cervical skull curvature [28]. The authors concluded that there is a link between morphological and functional features of the cervical spine in patients with TMD. D'Attilio et al. evaluated the cervical lordosis angle (CVT/EVT) in class II subjects with TMD and found a significant relationship between several cephalometric parameters and CVT/EVT, such as the following: maxillary and mandibular protrusion, mandibular length, overjet and overbite and significantly reduced cervical lordosis angle in TMD [26].
Di Giacomo et al., combined the standard cephalometric analysis with Rocabado's approach [43] for determining other cervical characteristics as follows: the craniocervical angle, the C0-C1 vertebrae distance, the C1-C2 vertebrae distance, the hyoid bone position [17]. The authors suggested that functional modifications in the mandible may influence cervical spine evaluation, although they did not find a relationship between class II and cervical spine alterations. Matheus et al. evaluated the association between DD and skull position related to the cervical spine by examining the craniocervical angle, the suboccipital space between C0-C1, the cervical curvature and the position of the hyoid bone [33]. They, too, found no proven link between TMD and the evaluated parameters. In addition, Câmara-Souza et al., by studying the position of the hyoid bone, the craniocervical angle and the occiput-atlas distance, found no association between TMD and cervical posture [25]. On the contrary, Flores et al. concluded that the anatomical and functional characteristics of the cervical spine in patients with TMD are related [28]. De Farias Neto et al. also found an association between craniocervical angles and distances and TMD, namely, flexion of the first cervical vertebra as well as hyperlordosis of the cervical spine [27].
The objectives of the prospective studies included in this systematic review were to evaluate the influence of occlusal splint therapy on cervical spine pain and range of movement in patients with myofascial pain or DDR [34] and, respectively, to determine whether an anterior repositioning splint (ARS) can effectively treat anterior DDR in juvenile class II patients [32]. The mean treatment duration with an ARS reported by Ma et al. [32] was 11.5 months. The authors reported significantly improved pain and function, therefore a successful treatment. In addition, Walczynska-Dragon et al. showed significant improvements in TMJ function after three months of occlusal splint therapy, with 78 percent of the participants experiencing no DDR symptoms [34].
The relationship between head posture, cervical pain and occlusion has been intensively studied and debated. Neck pain may be associated with forward head posture [42][43][44] whereas Manfredini et al. state that occlusal and postural features and TMDs are not related [45], and Haralur et al. found an influence of the head posture on dynamic occlusal parameters [46].
Nevertheless, the biomechanical behavior of the TMJ is considered to be influenced by the head posture [47]. Inoue et al. studied the relationship between TMJ DD diagnosed by MRI and muscle pain patterns and showed that DD is possibly associated with ipsilateral muscle soreness [48]. Still, it has been shown that there is a relationship between improved head and cervical posture and the reduction of TMD symptoms [49].
It has been shown that craniofacial morphology and the cervical spine are interrelated structures [50,51]. Although there are relationships between occlusal variables and postural changes, there is little actual data to suggest a direct causal correlation [52]. An awkward posture is shown to be involved in neck pain [53] as well as the biomechanical posture of the cervical spine [54].
Although in the presented case we did not measure the Cobb's angle for evaluating the cervical lordosis, it is obvious that the cervical spine has a vertical orientation by drawing the line connecting the second and seventh cervical vertebrae, sustained also by the modified hyoid bone position. The change in the depth of the cervical skull curvature, as described by Penning [55] and highlighted by Flores et al., was modified in TMD patients, implying the absence of the physiological lordosis of the cervical spine [28]. This is in accordance with our findings. The reduced hyoid triangle is encountered when the neck muscles are stretched and tensioned. The hyoid bone is a functional unit that allows mandibular and cervical dynamics [56]. The modifications of the hyoid triangle were related to TMD [24], which is in concordance with our findings, which showed a major increase in the hyoid triangle. Flores et al., have shown that in subjects with TMD the craniovertebral angle was decreased (below 96 • ) [28], whereas our patient had a craniovertebral angle of 100 • , but with similar symptomatology.
The space between C2 and C3 vertebrae was decreased, also the C2 vertebrae showed a rotation, which could lead to transmitting an increased pressure on the spinal nerves. Concerning the functionality of the atlanto-occipital joint, involved in flexion and extension of the head, our findings are in concordance with the authors of de Farias Neto et al., who showed that in subjects with TMD there was an increased predisposition to flexion [27]. Greenbaum et al., when investigating the connection between TMDs and upper neck performance, have shown that subjects with pain-related TMD diagnoses are more likely to have considerable upper-neck hypomobility and poor muscle assets than patients with intra-articular TMDs [57]. On the contrary, our case report showed neck-related symptoms as well as bilateral disk displacement with reduction and left joint effusion, indicating an intracapsular disorder. Nevertheless, it has been reported that in patients with myogenic temporomandibular dysfunction, especially in women, there is a possibility that the higher cervical joints (C1-C2) are involved, the cervical range of motion and the extent of rotation during cervical flexion being reduced [58]. Moreover, Greenbaum et al. pointed out that cervicogenic headache was associated with pain-related TMDs, especially hypomobility and upper neck symptoms [59]. Our case also had upper cervical spine modifications, which could highlight the above-mentioned statements.
A debate relates to the changes in the vertical dimension of the head and changes in the craniocervical relationships. Solow and Tallgren found associations between craniofacial morphology and head posture [60], as well as Sharma et al. have found [61]. Liu et al. have described that subjects with skeletal class II patterns had a tendency to have a more extended head [62], with techniques of extension traction restoring lordosis in the cervical spine [63].
When Derwich et al., was studying craniovertebral and craniomandibular changes in patients with TMDs, have shown that the vertical and sagittal position of the mandible, as well as the width of the functional space between C1 and C2, were considerably influenced by combined occlusal splint therapy and physiotherapy [64].
McCormick et al. have shown that spinal cord compression may lead to neck pain [65]. Due to the fact that the head and neck complex are maintained in a neutral posture by the muscle forces [66], any disruption between the equilibrium of the muscles or the axial position of the vertebrae could lead to cervical and temporomandibular joint pain. Our presented case had a low anterior facial height and a hypodivergent profile and class II skeletal pattern, indicating a muscle imbalance of the neck muscles, leading to the pain symptoms. It has been shown that in children with class II malocclusion, low-intensity pulsed ultrasound (LIPU) associated with functional therapy may aid in mandible growth stimulation [67]. In adults, LIPU, due to its properties in soft tissue repair and bone regeneration, is used to stimulate mandibular condylar cartilage tissue regeneration and to decrease the progression and development of osteoarthritis [68]. At first, we considered LIPU in conjunction with the occlusal splint and physiotherapy to treat the joint effusion, but we decided to postpone this treatment method due to the patient's lack of joint pain.
Obtaining correct facial proportions, controlling the factors that influence the hyoid bone position and maintaining the functionality of the mandible, as well as pain relief by myorelaxant agents, nonsteroidal anti-inflammatory drugs and physiotherapy/kinetotherapy, is vital in obtaining functional harmony. Occlusal splints may contribute to increasing the vertical dimension of occlusion, therefore aiding in symptom relief, being part of this complex treatment approach.

Implications for Practice and Future Research
Based on the systematic review results and the reported case, there is evidence suggesting a correlation between cervical pain, head posture and temporomandibular disorders. The recommendations regarding therapy refer to conservative therapy as a first step, including pharmacologic treatments (non-steroidal anti-inflammatory drugs) associated with cognitive behavior therapy and biofeedback in order to improve short-and long-term pain management, as well as physical therapy [69]. Among the most commonly reported conservative therapies are custom-made occlusal splints and massage therapies, with additional methods being light and laser therapy or drugs [70].
Following a re-evaluation performed in two to four weeks, other conservative measures could be considered as well, such as relaxing therapies for muscle spasms and occlusal splints. Occlusal adjustments and orthognathic surgery, as well as joint surgery, might also be taken into consideration; however, surgical procedures (arthrocentesis, arthroscopy, diskectomy, condylotomy, total joint replacement) are rarely indicated in the case of TMDs; usually, they are chosen for correction of anatomic or articular abnormalities [71][72][73]. Surgical techniques, such as arthrocentesis, should be considered in refractory cases after a six-month period of splint treatment with no pain improvement or symptom relief. Due to the possible associations between head and neck pathology and TMD symptoms, a specialist in the cervical spine (physio/kineto therapist) with knowledge of the TMD area should be included in the workflow of this complex disease approach.
The relationship between TMD, head and neck posture and the skeletal pattern is still challenging. We tried to enlighten the connection between these, although the literature still debates contradictory opinions. We believe that a connection between them exists; however, which one relates to the other in terms of sequence, causality or influence is unclear. Correcting a malposition of the spine or a dental malocclusion still remains challenging in terms of TMD prevention.
Considering that craniocervical posture is related to facial characteristics and temporomandibular joint disorders, we emphasize the need for careful consideration of the muscle equilibrium of the head and neck, as it can have an impact on treatment outcome. We consider that the results of this review are relevant for practitioners, as they can reveal a possible association between skeletal pattern [74], cervical spine posture and TMD that may assist in treatment planning. We attempted to identify future areas of interest in the medical field that need more investigation. However, due to the limited methodological quality of the studies and the heterogeneity of the data, results should be interpreted with caution.

Conclusions
Based on the results found by performing the systematic review, we can conclude that the association between head position, cervical symptoms and occlusion has been investigated and debated intensively. Additionally, while the literature still shows contradictory opinions, a relationship between TMD and cervical posture has been revealed.
According to the literature, occlusal splint therapy can result in significant improvements in TMJ function. Occlusion, postural alterations, craniofacial morphology and TMD have been correlated. The findings revealed by reviewing the existing literature are consistent with the case report disclosed.
The lack of physiological lordosis, associated with modifications of the hyoid triangle and a decreased space between C2 and C3 vertebrae, may explain an over-pressure on the spinal nerves and the overall patient's symptomatology. In this context, the literature suggests that occlusal splints, as part of this comprehensive therapeutic approach, may help to increase the vertical dimension of occlusion, therefore aiding in symptom relief.
Based on our findings, we believe that further research should be performed based on a higher number of subjects with TMD and cervical spine modifications, using the RDC/TMD protocol, cervical examination protocol and MRI.
There is a relationship between TMD and symptoms, as well as the cervical spine and occlusion. The treatment guidelines should include the cervical spine assessment as part of the initial reversible therapy and, in addition, postural treatment with a physiotherapist and a kinetotherapist, as well as splints for occlusion, without irreversible alterations to the dentition. The first treatment option aims to alleviate symptoms by addressing the spine while using splint therapy, with irreversible tooth changes being considered only afterward (orthodontics, prosthodontics). Other specialists are being considered as well, yet this approach may be included in the RDC/TMD protocol in the future. Informed Consent Statement: Written informed consent for publication has been obtained from the patient to publish this paper.

Conflicts of Interest:
The authors declare no conflict of interest.