Lambert G.M. de Bont

TISSUE RESPONSES TO DEGENERATIVE CHANGES IN THE TEMPOROMANDIBULAR-JOINT - A REVIEW

The articular cartilage covering of the mandibular condyle and the articular eminence, as well as the tissue of the articular disc, may be affected by degenerative changes associated with osteoarthrosis. Degenerative changes of cartilage alter its physical properties and, as a result, affect its ability to withstand compressive and shearing stresses. Increased friction between the articular surfaces may impair joint movement and may elicit compensatory or pathologic responses of the cartilage and the adjacent tissues, such as capsule and ligaments, synovial membrane, subchondral bone, and associated musculature. In this review, these structural changes are described and related to common signs and symptoms of craniomandibular dysfunction, such as clicking, locking and instability, pain and tenderness, restricted ranges of mandibular motion, crepitation, deformity, muscle wasting, and changes of occlusion.

The structure, biochemistry, and metabolism of osteoarthritic cartilage: A review of the literature

PURPOSE To understand the possible significance of the presence of proteases, cytokines, growth factors, and arachidonic acid metabolites in the osteoarthritic temporomandibular joint (TMJ), the pathogenesis of TMJ osteoarthritis (OA) is discussed, based on knowledge of structure, biochemistry and metabolism of osteoarthritic cartilage in general, and a classification of TMJ OA is presented.

Pathology of temporomandibular joint internal derangement and osteoarthrosis

Temporomandibular joint (TMJ) osteoarthrosis and disk displacement seem to be strongly related, but they may also represent mutually independent temporomandibular disorders. This paper presents relevant aspects of normal physiology and degeneration of synovial joints, aspects of normal temporomandibular articular disk physiology and of displacement of the disk, the relationship between TMJ osteoarthrosis and disk displacement, and a general classification of temporomandibular disorders.

Evaluation of Temporomandibular Joint Prostheses: Review of the Literature From 1946 to 1994 and Implications for Future Prosthesis Designs

PURPOSE This article describes the useful elements of applied temporomandibular joint (TMJ) prostheses and discusses the factors necessary to be addressed in an appropriate TMJ prostheses design. MATERIALS AND METHODS Information about TMJ prostheses was gathered by a literature search. Only designs with the primary intention of true joint replacement were selected. The designs were divided in fossa-eminence, condylar, and total joint replacements, which are reviewed separately. RESULTS A fossa-eminence prosthesis can be fixed by a metal plate screwed to the root of the zygomatic arch. A condylar prosthesis can be fixed by a metal plate screwed to the mandibular ramus and fitted by bending the plate or using different sizes. All reviewed designs resulted in a loss of translational movements of the mandible, especially in an anterior direction. Although the recent designs use the same materials as are used in hip and knee joint prostheses, the wear properties of the existing TMJ prostheses are still unknown. CONCLUSIONS A future prosthesis must imitate the anterior movement of the mandible when the mouth is opened and also allow some mediolateral movement. The fitting to the skull is still a major problem, as is the combination of the required motions and low wear rates. To confirm good clinical performance of a new TMJ prosthesis, long-term follow-up studies are necessary.

Epidemiology and natural progression of articular temporomandibular disorders

The reported prevalence of temporomandibular disorders (TMDs) differs from study to study, probably because of methodologic errors and lack of standardized definitions of TMDs and their characteristics. Classification of TMDs should be in accordance with classification of synovial joint disorders as generally used by rheumatologists and orthopedic surgeons, in which articular disorders are distinguished from nonarticular disorders. Articular temporomandibular disorders appear to be self-limiting in a very high percentage of cases. Because of this nonprogressive nature, the outcome of nonsurgical management will be highly successful.

NORMAL CARTILAGE STRUCTURE, BIOCHEMISTRY, AND METABOLISM - A REVIEW OF THE LITERATURE

PURPOSE To understand the possible significance of the presence of proteases, cytokines, growth factors, and arachidonic acid metabolites in the osteoarthritic temporomandibular joint (TMJ), a review of the normal physiologic processes and participating factors in the normal TMJ is established, based on knowledge of structure, biochemistry and metabolism of normal cartilage in general.

Oral Appliance Versus Continuous Positive Airway Pressure in Obstructive Sleep Apnea Syndrome: A 2-Year Follow-up

STUDY OBJECTIVES Oral appliance therapy has emerged as an important alternative to continuous positive airway pressure (CPAP) in treating patients with obstructive sleep apnea syndrome (OSAS). In this study we report about the subjective and objective treatment outcome of oral appliance therapy and CPAP in patients with OSAS. DESIGN Cohort study of a previously conducted randomized clinical trial. SETTING University Medical Center, Groningen, The Netherlands. PATIENTS OR PARTICIPANTS One hundred three patients with OSAS. INTERVENTIONS CPAP and oral appliance therapy (Thornton Adjustable Positioner type-1, Airway Management, Inc., Dallas, TX, USA). MEASUREMENTS AND RESULTS Objective (polysomnography) and subjective (Epworth Sleepiness Scale, Functional Outcomes of Sleep Questionnaire, Medical Outcomes Study 36-item Short Form Health Survey [SF-36]) parameters were assessed after 1 and 2 years of treatment. Treatment was considered successful when the apnea-hypopnea index (AHI) was < 5 or showed substantial reduction, defined as reduction in the index of at least 50% from the baseline value to a value of < 20 in a patient without OSAS symptoms while undergoing therapy. Regarding the proportions of successful treatments, no significant difference was found between oral appliance therapy and CPAP in treating mild to severe OSAS in a 2-year follow-up. More patients (not significant) dropped out under oral appliance therapy (47%) compared with CPAP (33%). Both therapies showed substantial improvements in polysomnographic and neurobehavioral outcomes. However, CPAP was more effective in lowering the AHI and showed higher oxyhemoglobin saturation levels compared to oral appliance therapy (P < 0.05). CONCLUSIONS Oral appliance therapy should be considered as a viable treatment alternative to continuous positive airway pressure (CPAP) in patients with mild to moderate obstructive sleep apnea syndrome (OSAS). In patients with severe OSAS, CPAP remains the treatment of first choice. CLINICAL TRIAL INFORMATION The original randomized clinical trial, of which this study is a 2-year follow-up, is registered at ISRCTN.org; identifier: ISRCTN18174167; trial name: Management of the obstructive sleep apnea-hypopnea syndrome: oral appliance versus continuous positive airway pressure therapy; URL: http://www.controlled-trials.com/ISRCTN18174167.

Synovial membrane involvement in osteoarthritic temporomandibular joints : A light microscopic study

OBJECTIVE To study the light microscopic characteristics of the synovial membrane of osteoarthritic temporomandibular joints to evaluate synovial membrane involvement in the osteoarthritic process. STUDY DESIGN Synovial membrane biopsies were obtained during unilateral arthroscopy in 40 patients. Thirty-one temporomandibular joints were diagnosed with osteoarthritis. Osteoarthritis subgroups were defined on the basis of the presence of symptoms related to disk displacement and perforation. The control group consisted of nine temporomandibular joints that were not involved by osteoarthritis. During light microscopic examination of the synovial membranes, several light microscopic variables were recorded. Differences between groups and between subgroups were tested with chi 2 or Fishers exact tests with Mann-Whitney U tests and with Students t tests. RESULTS In the osteoarthritis group, the number of synovial intima cell layers was significantly higher, and fibrous intima matrix and fibrous subintima were found significantly more frequently than in the control group. Moreover, in the osteoarthritis group, intima cell hypertrophy in combination with a closely packed cell composition was found significantly more often in the first year of clinical signs and symptoms, whereas intima hyperplasia, fibrous intima matrix, dense surface material, and subintima elastic fibers were found significantly more frequently in the first 2 years of clinical signs and symptoms. CONCLUSIONS The findings in this study suggest that osteoarthritis of the temporomandibular joint may initially result in synovial intima hyperplasia and cell hypertrophy, and subsequently in deposition of fibrous material in the intima matrix. Eventually, fibrosis of the subintimal tissue may occur in combination with degeneration and subsequent normalization of the synovial intima cell layer. Overall, fibrosis was the most characteristic feature of synovial membranes of osteoarthritic temporomandibular joints. In conclusion, the involvement of the synovial membrane in osteoarthritis of the temporomandibular joint is characterized by an early proliferative phase and a late fibrous phase. It appears that the intense and prolonged fibrous phase may not be a normal appropriate response to an initial insult but rather an aberrant counterproductive response.

TMJ articular disc position and configuration 30 years after initial diagnosis of internal derangement

PURPOSE This study evaluates disc position and configuration on magnetic resonance imaging (MRI) in temporomandibular joints (TMJs) with a long history of internal derangement. PATIENTS AND METHODS Sagittal T1-weighted MRIs of 55 TMJs that were diagnosed with internal derangement approximately 30 years ago were made with the mouth closed and open, and the position and configuration of the articular disc were determined. For comparison, a control group consisting of 15 asymptomatic TMJs without clinical signs of internal derangement or of other TMJ disorders were studied in the same way. RESULTS Anterior disc position was found in 90% of the TMJs with a history of internal derangement. Reducing disc displacement was found in one third of these TMJs, whereas permanent displacement was found in two thirds. In four joints, no disc was discernible. In one of the joints of the control group, a permanent disc displacement was found; normal disc position was found in all other joints of the control group. A biconcave disc configuration, which was considered normal, was found only in TMJs with normal disc position or with reducing discs. CONCLUSION It was concluded that, after 30 years of displacement, the TMJ disc can be clearly identified on MRI in most cases. If the disc becomes permanently displaced, its configuration deviates from the normal biconcave configuration, and its anteroposterior length decreases. Convex and folded appearances of the disc are common in this situation. However, the disc usually maintains its biconcave configuration as long as it resumes its position on top of the condyle during mouth opening, even if this condition lasts for several decades.

Calcium pyrophosphate dihydrate crystal deposition disease: a review of the literature and a light and electron microscopic study of a case of the temporomandibular joint with numerous intracellular crystals in the chondrocytes

The pathogenesis of calcium pyrophosphate dihydrate (CPPD) crystal deposition disease of synovial joints is still unclear, although overproduction of extracellular pyrophosphate (PPi) is thought to play a key role. We studied the light and electron microscopic appearances of a case of CPPD crystal deposition disease of the temporomandibular joint (TMJ) in search of new clues for its pathogenesis. Light microscopic examination of CPPD-containing material from the joint space revealed cartilaginous nodules with various degrees of crystallization. Transmission electron microscopic examination revealed numerous extra- as well as intracellular crystals and crystal shaped spaces in the chondrocytes. Other striking ultrastructural features of the chondrocytes included the presence of many mitochondria, frequently containing crystalline material, and the presence of highly dilated rough endoplasmic reticulum and large glycogen islands. The presence of intramitochondrial crystals may hypothetically imply a derangement in mitochondrial adenosine triphosphate or PPi metabolism. The finding of intracellular CPPD crystals in chondrocytes points to the existence of an intracellular pathway of CPPD crystal formation in CPPD crystal deposition disease of the TMJ and possibly in CPPD crystal deposition disease in general.