Stress distribution in the temporomandibular joint affected by anterior disc displacement: a three‐dimensional analytic approach with the finite‐element method

Abstract

The purpose of this study was to investigate the influences of anterior disc displacement on TMJ loading during maximum clenching by use of finite-element analysis. Based on a young human dry skull, an analytic model of the mandible including the TMJ was developed. In addition to the standard model with normal disc-condyle relation, two models were designed to simulate various degrees of anterior disc displacement. In the standard model, compressive stresses were induced in the anterior, middle and lateral areas on the condyle and glenoid fossa, whereas tensile stresses were observed in the posterior and medial regions. In the models with anterior disc displacement, compressive stresses were recognized in all the areas of TMJ components excluding the bilaminar zone. Shear stresses in the articular disc and bilaminar zone significantly increased in most areas. In conclusion, stress distributions in the TMJ with a normal disc position was substantially different from those with anterior disc displacement, suggesting that the progress in disc displacement may have some association with the nature of stress distributions in the TMJ, in the articular disc in particular.

Temporomandibular Joint: Disorders, Treatments, and Biomechanics

“…Other possible causes include grinding or clenching the teeth, which puts a lot of pressure on the TMJ; dislocation of the disc; presence of osteoarthritis or rheumatoid arthritis in the TMJ; stress, which can cause a person to tighten facial and jaw muscles or clench the teeth; aging. 7,15,31,38,48,92,97 The most common TMJ disorders are pain dysfunction syndrome, internal derangement, arthritis, and traumas. 18, 21,22 TMD is seen most commonly in people between the ages of 20 and 40 years, and occurs more often in women than in men.…”

“…Disc displacement is the most common TMJ arthropathy and is defined as an abnormal relationship between the articular disc and condyle. 26,97 As the disc is forced out of the correct position there is often bone on bone contact which creates additional wear and tear on the joint, and often causes the TMD to worsen. 15,97 Disc displacement generates a popping sound when the disc is first forced out of alignment as the mouth opens up and then again as the disc is forced back into place as the mouth is closed.…”

“…26,97 As the disc is forced out of the correct position there is often bone on bone contact which creates additional wear and tear on the joint, and often causes the TMD to worsen. 15,97 Disc displacement generates a popping sound when the disc is first forced out of alignment as the mouth opens up and then again as the disc is forced back into place as the mouth is closed. Clinically, this popping sound or clicking is regarded as an initial symptom of the temporomandibular joint internal derangement (TMJ-ID).…”

“…Clinically, this popping sound or clicking is regarded as an initial symptom of the temporomandibular joint internal derangement (TMJ-ID). 97 The anterior disc displacement has different degrees of severity. Wilkes developed staging classifications for the TMJ related internal derangement, or disc displacement (see Table 1).…”

“…72,78,86 Almost 70% of TMD patients have disc displacement. 21,26 According to Tanaka et al 97 stress distributions in the TMJ with a normal disc position are substantially different from those with anterior disc displacement. It is suggested that the disc displacement induces the change of stress distribution in the disc and the increase of frictional coefficients between articular surfaces, resulting in the secondary tissue damage.…”