Temporomandibular Joint Disorders

CHAPTER 94 Temporomandibular Joint Disorders




Key Points















Temporomandibular disorders, or TMDs, is a collective term that has been used traditionally to describe multiple disorders. These include both intracapsular disorders, or true abnormalities of the temporomandibular joint (TMJ), and muscular disorders, or myofascial pain dysfunction syndrome (MPD). Additionally, some disorders have not been considered under the umbrella of TMD but either directly or indirectly affect the structures of the TMJ. Examples of these disorders are congenital and developmental deformities, trauma, and neoplastic disease.


The general presenting complaints of the temporomandibular disorders include facial pain, earache, and headache. Therefore it is important for otolaryngologists to be familiar with the diagnosis and treatment of these various conditions. Much of the difficulty encountered in the treatment of TMDs relates to the failure to distinguish between these disorders and other causes of head and facial pain because of the similarity of the signs and symptoms with which they present. The emphasis in this chapter is on the diagnosis of TMDs, with a subsequent discussion of what is known about the etiology of the various conditions, forming the basis for a rational approach to therapy.



Anatomy


The anatomy and function of the TMJ are unique in several ways. The TMJ is a diarthrotic joint. Because the mandible is hinged at both ends, each joint is incapable of independent movement. This is clinically important because dysfunction in one joint can adversely affect the function of the contralateral joint, producing bilateral symptoms.


Each individual joint consists of the condylar process of the mandible, which is housed within the glenoid fossa of the squamous portion of the temporal bone. The anterior wall of the glenoid fossa is formed by the articular eminence, which is the articulating counterpart to the condylar process. The articulating surfaces are lined with fibrous connective tissue and are enclosed by a fibrous capsule.


Interposed between the articulating surfaces of the TMJ is the articular disk. The disk is a unique structure that is concavo-convex on its superior surface and concave on its inferior surface, where it contacts the convex condylar head. The presence of the articular disk divides the joint into two distinct compartments and contributes to the dual action of this ginglymoarthrodial joint. The inferior compartment, or inferior joint space, allows for purely anterior and posterior rotational movement between the condyle and disk. The superior joint space allows for translational movement between the disk and the glenoid fossa and articular eminence. In addition to assisting movement within the joint, the disk acts to compensate for any incongruencies between the articular surfaces and acts as a shock absorber within the joint.1


The degree of condylar movement is governed by the limiting actions of the joint capsule, the articular disk, and the joint ligaments. The primary ligaments of the TMJ are the lateral, sphenomandibular, and stylomandibular ligaments. The relationship of the articulating components of the joints is also influenced by the presence of the teeth. When the mouth is in an open position, the degree and direction of movement of the joints are influenced by the components discussed earlier. However, when the teeth come into contact, this occlusal relationship determines the final position of the condyle with respect to the rest of the joint. This factor becomes increasingly important in individuals who exhibit occlusal disharmony or parafunctional habits.



Diseases and Disorders


The TMJ is susceptible to the same conditions that affect other joints in the body such as congenital and developmental anomalies, traumatic injuries, dislocations, internal derangements of the articular disk, ankylosis, various arthritic conditions, and, rarely, neoplastic diseases (Table 94-1). Although many of these conditions are treated in the same manner as in other joints, the previously described anatomic and functional differences of the TMJ often require some variations of therapy.








Intracapsular Disorders


Intracapsular disorders of the TMJ include the following: (1) anterior disk displacement with reduction on opening the mouth, (2) anterior disk displacement without reduction, and (3) degenerative joint disease.


Anterior disk displacement is typically caused by trauma. This may be a single, macrotraumatic event or, more likely, frequent episodes of microtrauma that occur over a prolonged period. The majority of microtraumatic events are the parafunctional habits such as tooth clenching or grinding, which is also known as bruxism.14



Anterior Disk Displacement with Reduction


Anterior disk displacement with reduction is typically characterized by clicking or popping sounds on mouth opening (Fig. 94-1). Reciprocal or closing clicks are not consistently present. Patients who present with anterior disk displacement with reduction generally exhibit a normal range of mandibular motion. There may or may not be pain associated with mandibular movement. Multiple studies have shown that asymptomatic anterior displacement with reduction is common and often persists for years without signs of progression.1416 It is believed that these asymptomatic, nonprogressive cases represent physiologic accommodation of the joint.17 They require no treatment. When pain is present, it is the general determinant of any functional limitation that exists. Treatment of these painful joints consists of soft diet, self-limitation of opening, NSAIDS, splint therapy, and physical therapy. Patients refractive to these conservative modes of therapy may be candidates for more invasive procedures such as arthrocentesis, arthroscopy, or open joint surgery.




Anterior Disk Displacement without Reduction


Anterior disk displacement without reduction is characterized by a closed lock (Fig. 94-2). In the nonreducing joint, forward translation of the condyle on mouth opening forces the disk anteriorly, causing it to become a physical impediment to further opening. The maximum interincisal opening (MIO) is generally only 25 to 30 mm, and the mandible deviates toward the affected joint. Lateral excursive movements of the mandible are generally restricted to the contralateral side but not to the ipsilateral side. Pain is a common symptom, particularly on forced opening (beyond the MIO).



Acutely displaced disks without reduction can often be successfully treated by manual manipulation of the mandible with coincident reduction of the disk. In chronic conditions, manual reduction is much less likely to lead to satisfactory reduction of the disk. This is generally due to loss of disk morphology. Patients who exhibit a chronically nonreducing disk should be initially treated with a stabilization splint in order to reduce the pressure on the retrodiskal tissues produced by masticatory and parafunctional forces. When pain is a significant component of this disorder, more aggressive or invasive procedures may be indicated.


Jun 5, 2016 | Posted by in OTOLARYNGOLOGY | Comments Off on Temporomandibular Joint Disorders

Full access? Get Clinical Tree

Get Clinical Tree app for offline access