The Effect of Removal of the Disc on the Friction in the Temporomandibular Joint
Purpose
The amount of friction in the temporomandibular joint (TMJ) is dependent on the joint components, including the synovial fluid, disc, and articular surface cartilage. As friction in the TMJ is less than in other (discless) joints, we hypothesized that this is caused by the presence of the disc.
Materials and Methods
The frictional coefficient of the TMJ was first measured in the intact porcine joint (n = 10). After the disc was removed the measurement of frictional coefficient was conducted again. Furthermore, the subsequent effects of loading duration and the application of hyaluronic acid (HA) were examined.
Results
The mean frictional coefficient in the intact joint was 0.0177 (SD 0.0021). After disc resection it became 0.0361 (SD 0.0063). The frictional coefficient increased with the length of the preceding loading duration and exceeded 0.0635 (SD 0.0085) after 30 minutes. Subsequent application of HA resulted in a slight decrease of the frictional coefficient.
Conclusions
The presence of the disc reduces the amount of friction in the TMJ. This reduction is likely due to the role of the disc in reducing the amount of incongruity between the articular surfaces and in increasing synovial fluid lubrication.
⁎Associate Professor, Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
†Graduate Student, Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
‡Assistant Professor, Department of Orthodontics, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
§Graduate Student, Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
‖Graduate Student, Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
¶Professor and Chair, Department of Functional Anatomy, ACTA, Amsterdam, The Netherlands.
#Professor and Chair, Division of Mechanical Science, Department of Systems and Human Science, Osaka University School of Engineering Science, Osaka, Japan.
⁎⁎Associate Professor, Department of Oral Maxillofacial Pathobiology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
††Professor and Chair, Department of Oral Maxillofacial Pathobiology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
‡‡Professor and Chair, Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
Address correspondence and reprint requests to Dr Tanaka: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
ABSTRACT