Previous reports of condylar movement have used arbitrary condylar, hinge axis and/or kinematic axis points as reference points. These reference points can suitably represent the path and amount of condylar movement, but understanding the relationship between condylar movement and anatomical structures from the resulting information is difficult. Four-dimensional (4 D) analysis of mandibular movement combines reconstructed three-dimensional images from computed tomography with mandibular movement data. This system can depict various condylar movements, including anatomical relationships between the condyle and temporal bone. The present study investigated the relationship between condylar deformity and the temporal bone using 4 D analysis of mandibular movement, achieving unprecedented anatomic and kinematic depiction of the movements. Deformity of the condyle accorded with corresponding temporal bone at a slightly protrusive mandibular position. Given this result, we suggest that a path of lateral excursion may represent one cause of osteoarthritic TMJ.

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A variety of surgical procedures are available for the treatment of recurrent dislocation of the temporomandibular joint, among which less invasive procedures are always preferred. We have developed an arthroscopic Nd-YAG laser surgery procedure (1986) combined with disc suture-fixation technique (1989) and applied these techniques without opening the joint in cases of recurrent dislocation of the temporomandibular joint requiring surgical treatment. This report briefly reviews the long-term follow-up data on these treated cases. The procedure comprises arthroscopic observation of the upper joint cavity and subsequent endoscopic infliction of fresh wounds from the posterior aspect of the disc in the upper joint cavity structures such as the oblique protuberance of the posterior wall of the upper joint cavity, the mandibular fosse, the articulator tubercle and the medial wall synovium by means of arthroscopic laser surgery (Advanced Medical Care, Ministry of Health and Welfare, Health Insurance Bureau, No. 5). Through the subsequent endoscopic disc suture-fixation process, sutured/stitched tissues posterior to the articular disc are fixed by traction onto the posterior wall and eventually adhere to the mandibular fossa and tubercle surface, resulting in contraction or disappearance of the upper joint cavity and in limitation of mandibular head movement. This surgical procedure has proven to be useful as a minimally invasive surgical technique for correction of recurrent temporomandibular joint dislocation. It permits the objectve to be achieved without involving joint opening, is repeatable, and hence is less invasive than the conventional open surgical procedures. Surgical treatment with this operative procedure has been indicated for a total of 35 jaw joints in 23 patients during the 17-year period from 1986 to 2002, and of these, only a single joint developed recurrence necessitating re-operation. All patients including this one case have since been progressing without recurrence or any problematic events.

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Forty-one closed lock cases were subjected to arthroscopic examination, and the relation between the presence of adhesion in the upper joint cavity and the change of mouth opening range after local anesthesia to the temporomandibular joint was evaluated.
In patients with adhesion, the change of mouth opening range after local anesthesia to the temporomandibular joint was smaller than that in patients without adhesion. In patients whose mouth opening range became more than 39mm and increased by over 11mm after local anesthesia, adhesion in the upper joint cavity was observed in 0%. On the other hand, in patients whose mouth opening range became less than 38mm or increased by under 10mm after local anesthesia, the prevalence of adhesion was 80% and 75%, respectively.
In order to diagnose adhesion before pumping or arthrocentesis, measurement of mouth opening range after local anesthesia to the temporomandibular joint is an easy and effective procedure.

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Purpose: A three-dimensional finite element model of the mandible including the temporomandibular joint (TMJ) was constructed to examine the biomechanical influences of changes in the mandibular morphology on TMJ. This study investigated the influences of changes in the horizontal condylar angle and gonial angle on the condylar displacement.
Methods: Based on a juvenile human dry skull specimen and the specimen containing the TMJ, which was sliced into serial sections, a numerical model of the mandible, including the TMJ, was developed. In this model, the ramus of the mandible is modeled by rigid beam elements, and thus the horizontal condylar angle and the gonial angle can easily be changed. The direction of the condylar displacement was analyzed with respect to changes in the horizontal condylar angle and gonial angle.
Results:
1. In changes in the horizontal condylar angle, the direction of the condylar displacement was influenced in unilateral occlusion, but was not influenced in bilateral occlusion.
2. When the gonial angle was opened, the direction of the condylar displacement migrated to the anterior. On the other hand, when the gonial angle was narrowed, the direction of the condylar displacement migrated upward.
Conclusions: It was found that changes in the horizontal condylar angle and gonial angle influenced the direction of the condylar displacement.

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This study simulated the influences of changes in the horizontal condylar angle and gonial angle on the disc displacement. A three-dimensional finite element model of the mandible including the temporomandibular joint (TMJ) and a model that changes the horizontal condylar angle and gonial angle were constructed. A load condition, which was clenching, was given to these models, and the direction of disc displacement was examined. The direction of disc displacement was analyzed with respect to changes in the horizontal condylar angle and gonial angle.
The results were as follows:
1. In the standard model, the disc displaced forward and upward without displacement in the mediolateral direction. The lateral area of the disc displaced in the lateral direction, and the central and medial area of the disc displaced in the medial direction.
2. Changing the horizontal condylar angle influenced the mediolateral direction of the disc. When the horizontal condylar angle increased, the disc displaced further in the lateral direction.
3. Changing the gonial angle influenced the anteroupward direction of the disc. When the gonial angle increased, the disc displaced in the forward direction, and when the gonial angle decreased, the disc displaced further in the upward direction.
Conclusions: It was found that changes in the horizontal condylar angle and gonial angle influenced the disc displacement.

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To evaluate the efficacy of drug therapy in the treatment of patients with temporomandibular disorders, we investigated clinical characteristics and treatment outcome in 180 patients with TMD treated with drug therapy in our hospital from April 1997 to March 2002. The following results were obtained.
The patients were 65 males and 115 females. The largest group of patients was the 20s age group (54 cases). Thirty patients were type I, 39 patients type II, 33 patients type IIIa, 58 patients type IIIb and 19 patients type IV. One hundred and thirty-four patients came to the hospital with the chief complaint of temporomandibular joint pain and 42 patients came with the chief complaint of trismus.
We treated 62 cases with only drug therapy, and 118 cases with drug therapy and other therapies. We gave only non steroidal anti-inflammatory drugs (NSAIDs) in 114 cases, only muscle relaxants in 26 cases and both of them in 36 cases. The most frequently used drugs were ampiroxicam in NSAIDs, and tolperisone hydrochloride in muscle relaxants.
As for prognosis in 134 cases, 15 cases (11.2%) were completely healed, 42 cases (31.3%) were almost completely healed, 35 cases (26.1%) had some improvements in their symptom, but 42 cases (31.3%) were not improved. Better clinical outcome was obtained in patients with type I and with type II.

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