|
Temporomandibular Joint (TMJ) Dysfunction
and
Emotional Stress
Physiological effects of emotional stress on the body and its effects on the TMJ
Effects on the musculoskeletal system
Bones
In addition to cortical and trabecular bone, TMJ is composed of cartilage, ligaments and dense fibrous tissue containing proteoglycans and collagens. As the
TMJ articular cartilage is anchored into subarticular bone, their stress distributions are constrained respectively by movements between the mandibular condyle and temporal bone (TMJ).(Ravosa, Kunwar, Stock, & Stack, 2007)
There is a number of animal studies demonstrating the plastic changes in cranial and facial skeleton as a result of the increased load on TMJ. Human experiments, however, are limited due to obvious ethical problems involved in examining histological changes as a result of artificially changed mechanical overload.
Although, in a good example of primate experiment, macaques on an over-use/hard diet developed higher density of connective tissue and thicker condylar articular cartilage.(Bouvier & Hylander, 1981)
Another study done on rabbits has demonstrated that altering TMJ force application by tooth extraction or unilateral bite raise has resulted in gene expression changes and elevated glycosaminoglycan (GAG) content in condylar cartilage. Due to the elevated viscoelasticity of proteoglycan-rich tissues in joints subjected to cumulatively low stresses, analyses suggest that articular cartilage and fibrocartilage of such organisms are able to resist greater compressive stresses than that of repetitively over-loaded cranial joints.
Further analysis has shown that routine overloading induces accelerated cell death and increased cartilage degradation supporting the hypothesis that cartilage exhibits a compensatory adaptive response to joint over-loading. The authors also conclude that a component of the adaptive increases in TMJ proportions and biomineralization represent a compensatory mechanism to cartilage degradation.(Ravosa et al., 2007)
The above findings can be incorporated into the clinical picture of an osteopathic patient subjected to emotional stress. Bruxism and increased muscle tone resulting from emotional stress change TMJ biomechanics and can cause degenerative changes in the cartilage together with altered mineralization of the cranial bones. It is also interesting to note that biomineralization changes in the bones can correlate with osteopathic findings such as compaction of the joint or intraosseous lesions.(Zverev & Remizov, 2007)
|