Diseases affecting Temporomandibular Joint (2) 口腔病理學 Diseases affecting Temporomandibular Joint (2) 顳 顎 關 節 疾 病 (2) 陳玉昆教授: 高雄醫學大學 口腔病理科 07-3121101~2755 yukkwa@kmu.edu.tw

學 習 目 標 Understanding: 1. Temporomandibular joint disorders 2. Patient evaluation 3. Examination 4. Imaging 5. Main pathological conditions affecting TMJ

參考資料 References: Oral Pathology for the Dental Hygienist. Olga AC Ibsen, Joan Anderson Phelan, 4th edition, 2004, Chapter 10, p. 356-364 Eric Whaites: Essentials of dental radiography & radiology 3rd edition, Chapter 29, p. 371-388 自購網路資源：super_toolcool

Normal Joint Function Harmonious function of temporomandibular joint depends on various factors. Anatomic relationship of condyle-disk complex governs smooth functioning of mandible. Whereas muscles of mastication are the machinery that powers mandibular movement, anatomic joint structures, such as condyle, articular eminence, and disk, act as the gears or bearings of the jaw. Refs. 1, 3

Normal Joint Function Normal joint function the jaw begins at a rest position of maximum occlusal contact. In this position, condyle rests within glenoid fossa, with articular disk situated between condyle, roof of glenoid fossa, and articular eminence. Rest position Mouth closed Refs. 1, 2

Normal Joint Function Rotary and translatory movements of condyle during normal mouth opening Rest position Mouth closed Primary rotation opened Translation initially widely Secondary 1 2 3 4 Ref. 2

Temporomandibular Disorders Temporomandibular disorders (TMDs) are caused by abnormalities in the functioning of temporomandibular joint or associated structures and these have been a clinical & diagnostic challenge in dentistry for many years. Most studies suggest that clinically significant TMD-related jaw pain, dysfunction, or both affects about 5% of the general population. Significant more frequent and more severe TMD signs & symptoms are seen in women & older adults. Ref. 1

Pathophysiology of Temporomandibular Joint Disorders Trauma affecting the temporomandibular joint is classified as direct (assault), indirect (whiplash injury), or secondary to parafunctional habits (clenching, bruxism). Other contributing factors include dentofacial deformities and psychosocial factors. TMDs may also be the result of disorders in growth & development (condylar hyperplasia or hypoplasia). Ref. 1

Pathophysiology of Temporomandibular Joint Disorders Iatrogenic causes of TMDs include indiscriminate use of corticosteroid injection into the joint. Numerous studies continue to dispute the significance of occlusal relationships. TMJ abnormalities are also associated with a systemic diseases such as rheumatoid arthritis and osteoarthrities. Ref. 1

Patient Evaluation History Trismus Malocclusion Parafunctional habits (bruxing, clenching) Dental symptoms Extensive dental or orthodontic treatment History of surgical treatment of jaws Progression of symptoms (sudden, gradual) Precipitating events (mastication, spontaneous, yawning) Ref. 1

Examination Ausculation (using a stethoscope) and palpation. Clinician relates joint noises such as clicking, crepitus. (crackling), or popping to the mandibular movement cycle. Muscles of mastication are palpated to determine tenderness. Patient is asked to move the mandible in a normal rotation (hinge) and translatory (forward slide) cycle. Interincisal opening is measured with any obvious deviation of motion to the right or left side. Ref. 1

Examination Patient’s ability to manipulate the mandible into right and left lateral excursions is noted. Patient is asked to protrude mandible to determine whether any deviations or disk interferences exist within joint. Patient’s occlusion is evaluated to determine gross abnormalities and whether occlusal abnormalities are related to patient’s temporomandibular problem. Ref. 1

Investigations Conventional radiographic projections Other techniques and investigations Transcranial Transpharyngeal Panoramic Reverse Town’s Transorbital Tomography, linear

Summary of different parts of TMJ shown by conventional projections Transcranial Lateral aspect of: Glenoid fossa Articular eminence Joint space Condylar head Transpharyngeal Lateral view of: Condylar head & neck Articular eminence Dental panoramic Lateral view of tomograph both condylar heads Reverse Towne’s Posterior view of: both condylar head & necks Transorbital Anterior view of: Condylar head & neck Articular eminence Tomography All aspects of: Glenoid fossa Articular eminence Joint space Condylar head Ref. 1

Main pathological conditions affecting TMJ TMJ pain dysfunction syndrome Internal derangements Osteoarthritis Juvenile rheumatoid arthritis (Still’s disease) Ankylosis Tumors Fractures Developmental anomalies (史迪爾氏症)

Summaries Knowing: Three factors implicated in TMD Two symptoms suggestive of TMD Imaging methods for TMD Main pathological conditions affecting TMJ