Sunday, December 14, 2008
The study of mechanics of the temporomandibularjoint (TMJ) is important because its dysfunction and breakdown could be, at least partially, of mechanical origin. The incongruity of the articular surfaces of the TMJ is compensated by a fibrocartilaginous articular disc. Its dislocation and failure seem to be closely related to the development of osteoarthritis of the TMJ.
Studies performed of the dynamics of TMJ with the MRI indicate that both TMJs are loaded during chewing, the balancing side more so than the working joint. In fact, during chewing, the intra-articular distance is smaller for hard than for soft food, on closing than on opening, on the balancing than on the working side. This last finding is confirmed by static biting experiments, in which the condyle-fossa distance decreases more on the side contralateral to the bite force, depending on its magnitude.
Also studies on the dynamics of compression areas indicate that plowing can occur through the disc during function, especially mediolaterally, due to stress field translation. This effect might contribute to cartilage wear and fatigue also because the disc is weaker mediolaterally. Further data indicate that the lateral area of the disc is mostly exposed to a higher mechanical energy density. Gallo LM. Modeling of temporomandibularjoint function using MRI and jaw-tracking technologies–mechanics. SourceCells Tissues Organs. 180(1):54-68, 2005.
The purpose of this next study is to examine whether electromyographic activity (EMG) during chewing movement changes towards the control level spontaneously in the subsequent course after diagnosis in patients with non-reducing disc displacement of the temporomandibularjoint (TMJ) who do not receive any treatment.
In 15 such patients, EMG data were examined at initial visit and at a mean follow-up of 21.7 months. As a control, 23 persons who had no TMJ dysfunction were studied. The results of EMG were compared among patients at initial visit, those at follow-up, and controls. The patients' clinical signs and symptoms were alleviated during the follow-up period.
Duration of muscle contraction, cycle time and integrated EMG value (IEMG) at initial visit in patients were significantly different from those in the controls. In patients, IEMG for chewing -side masseter during chewing in the TMJ-affected side was greater at follow-up than that at initial visit. In patients, duration of muscle contraction or cycle time at follow-up was not different from that at initial visit.
Patients with non-reducing disc displacement of the TMJ showed spontaneous increasing of IEMG without any treatment in the subsequent course after diagnosis, coupled with improvement of clinical signs and symptoms. Duration of muscle contraction or cycle time did not change towards the control level. The results presented are useful as control data to understand the true effect of a particular treatment for patients with non-reducing disc displacement of the TMJ. ( Sato S. Kawamura H. Natural course of non-reducing disc displacement of the temporomandibularjoint: changes in electromyographic activity during chewing movement. Journal of Oral Rehabilitation. 32(3):159-65, 2005)
www.stopmusclepain.com
arthritis,
chewing,
pain,
TMJ
Sunday, December 14, 2008
The study of mechanics of the temporomandibularjoint (TMJ) is important because its dysfunction and breakdown could be, at least partially, of mechanical origin. The incongruity of the articular surfaces of the TMJ is compensated by a fibrocartilaginous articular disc. Its dislocation and failure seem to be closely related to the development of osteoarthritis of the TMJ.
Studies performed of the dynamics of TMJ with the MRI indicate that both TMJs are loaded during chewing, the balancing side more so than the working joint. In fact, during chewing, the intra-articular distance is smaller for hard than for soft food, on closing than on opening, on the balancing than on the working side. This last finding is confirmed by static biting experiments, in which the condyle-fossa distance decreases more on the side contralateral to the bite force, depending on its magnitude.
Also studies on the dynamics of compression areas indicate that plowing can occur through the disc during function, especially mediolaterally, due to stress field translation. This effect might contribute to cartilage wear and fatigue also because the disc is weaker mediolaterally. Further data indicate that the lateral area of the disc is mostly exposed to a higher mechanical energy density. Gallo LM. Modeling of temporomandibularjoint function using MRI and jaw-tracking technologies–mechanics. SourceCells Tissues Organs. 180(1):54-68, 2005.
The purpose of this next study is to examine whether electromyographic activity (EMG) during chewing movement changes towards the control level spontaneously in the subsequent course after diagnosis in patients with non-reducing disc displacement of the temporomandibularjoint (TMJ) who do not receive any treatment.
In 15 such patients, EMG data were examined at initial visit and at a mean follow-up of 21.7 months. As a control, 23 persons who had no TMJ dysfunction were studied. The results of EMG were compared among patients at initial visit, those at follow-up, and controls. The patients' clinical signs and symptoms were alleviated during the follow-up period.
Duration of muscle contraction, cycle time and integrated EMG value (IEMG) at initial visit in patients were significantly different from those in the controls. In patients, IEMG for chewing -side masseter during chewing in the TMJ-affected side was greater at follow-up than that at initial visit. In patients, duration of muscle contraction or cycle time at follow-up was not different from that at initial visit.
Patients with non-reducing disc displacement of the TMJ showed spontaneous increasing of IEMG without any treatment in the subsequent course after diagnosis, coupled with improvement of clinical signs and symptoms. Duration of muscle contraction or cycle time did not change towards the control level. The results presented are useful as control data to understand the true effect of a particular treatment for patients with non-reducing disc displacement of the TMJ. ( Sato S. Kawamura H. Natural course of non-reducing disc displacement of the temporomandibularjoint: changes in electromyographic activity during chewing movement. Journal of Oral Rehabilitation. 32(3):159-65, 2005)
www.stopmusclepain.com
arthritis, chewing, pain, TMJ