Table 1 Reaction forces of maxillary teeth and temporomandibular joint discs, calculated during simulated clenching with nonmodified geometry dental arches Location of Total reaction Total reaction force/moment in force in axis force in axis masticatory system X, N Y,N Right articular disc -65.
The created biomechanical model representing entire masticatory system consisted of eight basic parts: two rigid structures representing the mandibular and maxillary dental arches, two mandibular condyles, two mandibular fossae of temporal bone, and solid models of two articular discs.
There were five criteria for inclusion in the study: 1) confirmed active CH type 1 based on serial clinical and radiographic evaluations (serial lateral cephalograms and lateral temporomandibular joint [TMJ] cephalometric tomograms); 2) bilateral or unilateral high condylectomy to remove the active growth center and articular disc repositioning for group 2; 3) orthognathic surgery to correct the associated dentofacial deformity; 4) at least 2 years of postsurgical follow-up; and 5) adequate clinical and radiographic records for analysis.
Group 1 patients (n = 12) were treated with orthognathic surgery only, while group 2 patients (n = 42) had high condylectomy procedures, articular disc repositioning, and orthognathic surgery.
This peripheral blood supply, in all probability, allows peripheral tears of the TFCC to mount a reparative response, while the avascularity of the central portion of the TFCC renders the articular disc unable to repair or heal.
Since the articular disc is avascular, there is little chance for healing with repair, thus debridement is the treatment of choice.
This portal provides excellent visualization of the lunotriquetral interosseous ligament (LTIL), the articular cartilage over the proximal surface of the triquetrum, the ulnolunate and ulnotriquetral ligaments of the TFCC, and the triangular fibrocartilage (TFC), or articular disc.
In another study comparing arthrography to arthroscopy in patients who eventually underwent operative arthrotomies, arthroscopy was again more accurate than arthrography for identifying the size and location of ligament and articular disc injuries.
In contrast, MRI is useful in evaluating the soft tissues, particularly in its assessment of the articular disc
The articular disc
may or may not demonstrate significant deformation and degenerative changes, depending on the length of time that the disc has been displaced.
The most common cause of TMJ dysfunction is anterior and/or medial displacement of the articular disc
(also known as internal derangement of the TMJ) (Figure 1b).
Ameniscus is a crescent-shaped fibrocartilaginous structure that partly divides a joint cavity, unlike articular discs
, which completely separate the cavity.