Temporomandibular Joint Dysfunction

Introduction

The cause of temporomandibular pain can include masticatory dysfunction, myofacial pain syndromes, atypical facial pain, and temporomandibular joint (TMJ) abnormalities.

An estimated 30-40 % of the Western population may experience symptoms suggestive of TMJ dysfunction. A preponderance of young women are affected by these disorders.

Anatomy

The gross anatomy of the TMJ is unique but typical of most diathrodial synovial joints except for the following features:

1. Both TMJs function as a single unit (the so-called craniomandibular articulation)

2. The articular surfaces are lined by fibrocartilage,

3. Finally, the articular disk separates the joint into two spaces, each with a different function.

The articular disk is a biconcave structure composed of dense fibrous connective tissue.

It is anchored anteriorly to the superior head of the lateral pterygoid muscle and the eminentia articularis, inferiorly to the medial and lateral aspect of the mandibular condyle, and posteriorly in two zones.

Joint mechanics

The prime function of the mandible is chewing and speech. During a maximal jaw opening, the TMJ undergoes two separate motions, which are permitted by the two distinct joint spaces. The lower ginglymoid compartment is capable of simple hinge motion only, and it is here that the first 20 mm to 25 mm of interincisor jaw opening is achieved. The upper gliding compartment is capable of translatory motion anteriorly along the eminence and allows the last 15 mm to 20 mm of interincisor jaw opening to occur. It is only after translation past the height of the eminence that the additional 20 mm of rotation is possible.

The TMJ is capable of protrusion and retrusion as well as lateral excursion, with unilateral or bilateral movement in the upper joint spaces only. Humans display an envelope of jaw motion reflective of a combination of hinge and translation movement in the mandible. At rest the mandibular condyle lies inferior to the TMJ disk. On jaw opening, the condyle rotates to engage the intermediate zone of the disk, causing it to move anteriorly and come in contact with the eminence. At this point, further opening is achieved by translating with the condyle along the slope of the eminence. In the final stage of opening, the condyle rotates beneath the disk.

Salivary Gland Tumors

Neoplasms of the salivary glands comprise a small percentage of head and neck tumors.

Types of tumor

The parotid glands are the largest and are bilateral pre- and infra-auricular structures. The submandibular glands and the sublingual glands are similarly paired and lie below the mandible and in the floor of the mouth, respectively. The minor glands are scattered throughout the upper aerodigestive tract along the mucosal surfaces.

1. Pleomorphic adenoma (benign mixed tumor);

a. the most common benign tumor of all of the salivary glands.

b. typically, it is a firm, mobile, asymptomatic mass and has a pseudocapsule.

c. these lesions require adequate excision initially or they recur and can become locally invasive.

d. for lesions of the lateral lobe, superficial parotidectomy is the accepted treatment.

2.Warthin’s tumor (cystadenolymphomatosum);

a. a cystic tumor that occurs primarily in the parotid glands

b. men over 40 years of age

c. it can be bilateral in 10% to 15% of patients.

d. lateral parotidectomy is adequate treatment.

3.Necrotizing sialometaplasia;

a. a benign condition,

b. most commonly presenting on the palate (as an ulcerative mass)

c. it is thought to be a metaplastic reaction to local ischemia.

d. the significance of this lesion is that it looks grossly malignant and

histologically can mimic salivary malignancies.

e. unlike its malignant counterparts, necrotizing sialometaplasia resolves

without aggressive treatment.

Facial Fractures

Etiology: Maxillary fractures often result from high-energy blunt force injury to the facial skeleton. Typical mechanisms of trauma include motor vehicle accidents, altercations, and falls. The patterns of fracture propagation in midface trauma originates from the work of René Le Fort. In 1901. He concluded that predictable patterns of fractures follow certain types of injuries. Three predominant types were described.

LeFort I fractures (horizontal) may result from a force of injury directed low on the maxillary alveolar rim in a downward direction. The fracture extends from the nasal septum to the lateral pyriform rims, travels horizontally above the teeth apices, crosses below the zygomaticomaxillary junction, and traverses the pterygomaxillary junction to interrupt the pterygoid plates .

LeFort II fractures (pyramidal) may result from a blow to the lower or mid maxilla. Such a fracture has a pyramidal shape and extends from the nasal bridge at or below the nasofrontal suture through the frontal processes of the maxilla, inferolaterally through the

lacrimal bones and inferior orbital floor and rim through or near the inferior orbital foramen, and inferiorly through the anterior wall of the maxillary sinus; it then travels under the zygoma, across the pterygomaxillary fissure, and through the pterygoid plates .

LeFort III fractures (craniofacial dysjunctions), may follow impact to the nasal bridge or upper maxilla. These fractures start at the nasofrontal and frontomaxillary sutures and extend posteriorly along the medial wall of the orbit through the nasolacrimal groove and ethmoid bones.

The fracture continues along the floor of the orbit along the inferior orbital fissure and continues superolaterally through the lateral orbital wall, through the zygomaticofrontal junction and the zygomatic arch. Intranasally, a branch of the fracture extends through the base of the perpendicular plate of the ethmoid, through the vomer, and through the interface of the pterygoid plates to the base of the sphenoid .

In most instances, maxillary fractures are a combination of the various Le Fort types. In very high-energy blows, maxillary fractures may be associated with fractures to the mandible, cranium, or both (ie, panfacial).

Physical examination

Evaluation of the maxilla and facial bones should be undertaken only after the patient has been fully stabilized and life-threatening injuries have been addressed. In particular, airway considerations and intracranial injuries must take immediate priority.

Maxillofacial Trauma

Initial Management of the Trauma Patient

The initial assessment and management of a patient’s injuries must be completed in an accurate and systematic manner to quickly establish the extent of any injury to vital life-support systems. About

30 % of deaths caused by injury can be prevented when an organized and systematic approach is used

Death from trauma is within seconds or minutes of the injury due to;

1. 1. lacerations of the brain,

2. brainstem,

3. upper spinal cord,

4. heart,

5. aorta, or

6. other large vessels.

First few hours after injury (calls golden hours) is also important for life saving. Death is usually due to;

1. 1. central nervous system (CNS) injury

2. hemorrhage.

Sepsis, multiple organ failure, or pulmonary embolism is another reason of death within days or weeks.

Patients are assessed and treatment priorities are established based on patients’ injuries and the stability of their vital signs. Injuries can be divided into three general categories:

1. severe (airway, inadequate breathing ,hemorrhage, and circulatory system damage or shock)

2. urgent (injuries to the abdomen, orofacial structures, chest, or extremities) and

3. nonurgent (nonurgent injuries account for approximately 80% of all injuries)