It is easily conceived that occlusal alteration may be responsible for the onset or progression of temporomandibular disorders, but its exact role is still unknown. In this study using rats, Immunohistochemical changes of mandibular condylar cartilage after teeth extraction were examined.
Unilateral upper molars of rats were extracted, and temporomandibular joints were resected at intervals of 1, 2, 3, and 6 months after resection. The tissues were fixed with paraformaldehyde, embedded in paraffin after decalcification with EDTA, and then serial sections were prepared for Immunohistochemical examination of types I, II, and X collagen, chondroitin 4-sulfate (C4S), chondroitin 6-sulfate (C6S), keratan sulfate (KS), and dermatan sulfate proteglycan (DSPG).
In the rats, stainability for types I, II, and X collagen, C4S, KS, and DSPG were stronger, whereas that for C6S was weaker, than in the control. These findings confirmed that occlusal alteration causes changes in extracellular matrix components of the mandibular condylar cartilage.

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This article reports two cases of intracapsular fracture of the mandibular condyle. This kind of fracture may be caused by intrinsic mastication. Case 1 was a 70-year-old male who visited with complaints of pain of the left temporomandibular joint during function and opening limitation. Case 2 was a 59-year-old female, referred to by a local clinic, with complaints of pain and swelling of the right preauricular area and opening limitation. In both cases, the diagnosis was condylar surface fracture based on X-ray, CT, MRI findings and operation was performed to remove the fragments of the condyle. The patients began to perform mandibular movements 3 days after operation, and the pain and dysfunction have been al leviated. Fragments of the condyle were investigated pathologically. It was suggested that the condylar heads had bone degeneration before the fracture.

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The purpose of this study was to investigate the effect of the superior jointcompartment irrigation on TMD patients with TMJ pain. Arthrocentesis was performed in 49 TMD patients with unilateral TMJ pain resistan to conservative treatment. These patients were assigned nonartificially to two arthrocentesis tecnique groups. The 1st group (26 patients) was injected with a steroid solution after irrigation, and the 2nd group (23 patients) was only irrigated. The improvement rate of TMJ pain and maximal mouth opening (MMO) during 3 months after (1 week and 1, 2, and 3 months) arthrocentesis was compared in the two groups. The results were follows:
1) There was no significant difference between the improvement rate of the TMJ pain in the two groups at all times. The improvement rate was 76% in the 1st group and 71.5% in the 2nd group 3 months later.
2) There was no significant difference between the MMO in the two groups at all times. The MMO was 39.4mm in 1st group (pre-MMO: 32.2mm) and 40.6mm in 2nd group (pre-MMO: 32.4mm) 3 months later.

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The purpose of this study was to investigate the outcome of arthrocentesis to III b and IV type TMD patients with unilateral TMJ pain. Arthrocentesis was performed in 41 TMD patients (III b type: 22 patient, IV type: 19 patients). Prior to and 3 and 6 months after arthrocentesis, the condition of TMJ pain and maximal mouth opening (MMO) were evaluated. The results were as follows:
1) The improvement rate of TMJ pain was 63.5% in III b type patients and 89.4% in III type patients 3 months later. The average MMO was increased from 29.4±5.0mm (mean±SD) to 38.1±6.5mm in III b type patients, and from 33.9±6.1mm to 40.1±5.4mm in IV type patients 3 months later.
2) The patients that underwent arthroscopic surgery, pumping manipulation, or rearthrocentesis because of a poor response to arthrocentesis 3 months later, were excluded from the evaluated subjects 6 months later (III b: 6 patient, IV 3 patients). Nine of 16 III b type patients (56.3%) and 13 of 16 III type patients (81.3%) had no TMJ pain 6 months later. The average MMO was 41.9±5.3mm in III b type patients, and 42.8±4.8mm IV type patents 6 months later.
It was concluded that arthrocentesis was effective on the TMJ pain of TMD IV type patients compared with TMD III b type patients.

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It is reported that satisfactory therapeutic effects on temporomandibular disorders (TMD) in elderly females are hard to obtain. In order to study local and systemic factors on TMD, complication and past illness, life style, and oral habits of patients with or without TMD were examined by questionnaire. Patients used in this study were 52 with TMD and 55 without TMD. The results were as follows:
1. Complications such as gynecological diseases, circulation diseases or osteoporosis were seen in more than 20% of the patients in both groups. A significant difference (P<0.05) was found in osteoporosis between patients with TMD and those without TMD.
2. By comparing occurrence of tinnitus, stiff shoulder, and lumbar and knee pain in both groups, the frequency of stiff shoulder was significantly high (P<0.05) in those with TMD.
3. As for the life-style, the patients with TMD preferred hard foods more than the others (P<0.05). No significant difference between both groups was seen in exercise.
4. History of traumatic injury to TMJ area was less than 5% in both groups.
5. As for oral habits such as grinding and clenching, those with TMD had a significantly higher clenching habit than those without TMD (P<0.05).
The results showed that the patients with TMD preferred hard foods and had clenching habit more frequently than the patients without TMD. Furthermore, the incidence of osteoporosis was higher in the patients with TMD.

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In recent years, biochemical analyses of synovial fluid (SF) in the temporomandibular joint (TMJ) have been conducted. The authors of those studies suggested that the inflammatory mediators and the matrix metalloproteinases (MMP) play a role in TMJ disorders. In joint-degenerating disease like arthritis, MMP have been reported to possibly be involved in the cartilage degeneration. MMP activity in SF collected from the TMJ was detected by using an easy assay system with fluorescent peptides (NFF-2 and NFF-3) as a specific substrate for MMP. How MMP proteins contribute to the enzyme activity was investigated by using enzymography with gelatin and Western blot analysis. As a result, the fluorogenic assay showed that some MMP activities were highly increased in SF isolated from patients with inflammatory signs. Pro MMP-1, active MMP-2, pro MMP-3 and active MMP-3 in the SF were by using Western blot analysis. The active MMP-2 was detected in nearly all. SFs tested. The active form of MMP-3 was detected in SFs isolated from TMJ in which synovitis was confirmed by arthroscopy. The existence of active MMP-3 correlated with the increase in activity of the MMP. Thus it was concluded that MMP-2 and MMP-3 serve as markers to early degenerative changes in the TMJ articular cartilage.

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The purpose of this study was to obtain interior views of the temporomandibular joint (TMJ) by computed arthroscopic simulation. Volume-rendering the TMJ from cryosections of the Visible Human female on the Internet and fly-through into the simulated TMJ were performed with three dimensional processing software of Analyze_AVW on the Silicon Graphics 02 workstation. Fly-through provided computed arthroscopic images, in which the structures of the interior of the joint space and a partial defect of the articular disc were visualized. These results showed that computed arthroscopic simulation would be a new modality to observe the pathological changes in the TMJ in the near future.

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