Jun-Ichi Ishimaru

A model for osteoarthritis of the temporomandibular joint

There is a need for a simple, reproducible animal model of advanced osteoarthritis of the temporomandibular joint (TMJ). In this study, gentle removal of the condylar articular layer in the sheep TMJ resulted in an eburnated condyle with peripheral osteophytes, thin or perforated discs, and temporal surface proliferation. This model can be used for both the study of osteoarthritis and the evaluation of therapeutic methods.

The role of the disk in sheep temporomandibular joint ankylosis

OBJECTIVE The purpose of this study was to determine the role of the disk in intraarticular ankylosis of the temporomandibular joint. STUDY DESIGN Twelve adult sheep were divided into 2 groups. In group 1, removal of the temporal and condylar articular surfaces was performed on the right temporomandibular joint and the disk was maintained; in group 2, removal of the articular surfaces and diskectomy were performed on the right temporomandibular joint. One sheep from each group was killed just after surgery and 5 sheep from each group were killed at 3 months. The joints were examined radiologically, macroscopically, and histologically. The range of jaw movements was recorded preoperatively and at sacrifice. RESULTS Each of 2 sheep in group 2 had lost 4% of their body weight by 3 months; all of the other sheep maintained or increased their weight. The range of jaw motion to the right was significantly lower in group 2 than in group 1 (P<.01). In group 1, fibrous repair of the articular surface and regeneration of the condylar head was seen. In group 2, each of the joints showed a total fibrous ankylosis with some calcification. There was a statistically significant difference in radiologic score between the groups (P<.0001). Histologic scores for group 1 demonstrated significantly lower scores on the degree of ankylosis scale and degree of calcification scale (P<.0001). CONCLUSIONS This study showed that the presence of the disk prevented the development of fibrous intraarticular ankylosis of the temporomandibular joint.

The effect of an intra-articular bone fragment in the genesis of temporomandibular joint ankylosis

The aim of this study was to examine the effect of an intra-articular bone fragment on the genesis of temporomandibular joint (TMJ) ankylosis. Twenty-two adult sheep had a unilateral operation of removal of the temporal and condylar articular surfaces, plus discectomy with or without insertion of an intra-articular bone fragment. Functionally, radiologically, macroscopically and histologically, in the group with the intra-articular bone fragment, the joints showed more advanced ankylosis both at one and three months after the operation, as compared to the group with no intra-articular bone. This study shows that the bone fragment increases the extent of ankylosis in the sheep model. The clinical significance of the various experimental findings of this study and others in the same series is presented.

A sheep model for temporomandibular joint ankylosis

PURPOSE The purpose of this study was to develop an animal model for temporomandibular joint (TMJ) ankylosis. MATERIALS AND METHODS Five sheep had removal of the temporal and condylar articular surface plus discectomy in the right TMJ; the left side was used as a control. One sheep was killed just after operation and four at 3 months. The joints were examined histologically, and a scoring system was developed to evaluate the extent of the ankylosis. The range of jaw movement was compared between preoperatively and 3 months. RESULTS Two sheep lost 4% of their body weight by 3 months. The range of jaw movement, particularly to the left, decreased at 3 months (P < .001). The joint spaces were filled with fibrous tissue and cartilage-like tissue. Development of new bone from the damaged temporal and condylar surfaces was seen, but full bony fusion did not occur. The average histologic score of a zone was 4.9 on the degree-of-ankylosis scale and 1.7 on the degree-of-calcification scale. There were statistically significant differences between the operated and control TMJs for both changes (P < .0001). CONCLUSION Fibrous ankylosis occurs rapidly after removal of the TMJ articular surfaces and the disc. This model can be further developed to isolate relative factors in the development of ankylosis and in evaluation of different treatment methods.

The effect of hyaluronic acid on experimental temporomandibular joint osteoarthrosis in the sheep

PURPOSE The purpose of this study was to test the effect of repeated injections of hyaluronic acid (HA) on the sheep model of osteoarthrotic temporomandibular joint (TMJ) disease. MATERIALS AND METHODS Bilateral osteoarthrosis (OA) was induced in the TMJs of six sheep. HA was injected into one joint on 7, 10, 14, 17, and 21 days postoperatively. Normal saline was injected into the contralateral joint. Three sheep were killed at 1 month and 3 at 3 months. The joints were removed and examined macroscopically and histologically. A special scoring system was applied following the modified Mankins score to evaluate the histologic changes. RESULTS The control group showed severe osteoarthrotic changes in the condyle, deviation in form from normal morphology, and marked marrow fibrosis. The HA-treated group showed less deviation from normal condylar morphology. The histologic scores at 1 month were HA 12.6, control 24.2 (P < .001), and at 3 months were HA 6.9, control 18.9 (P < .001). There was a significant difference in osteoarthrotic changes between HA-treated and control TMJs, with the HA-treated TMJs having less severe changes. CONCLUSION Repeated intraarticular injections of HA into a sheep TMJ with experimentally induced OA minimizes the extent of osteoarthrotic change when compared with the control joint. Thus, HA may have a role in preventing the progression of TMJ OA.

A simple cryosurgical method for treatment of oral mucous cysts

A simple and easy cryosurgical method to treat intraoral mucous cysts is described. Twelve female and six male patients, with mucous cysts on the lower lip and the tip of the tongue, were treated by direct application of liquid nitrogen with a cotton swab. Each lesion was exposed to four or five cycles composed of freezings of 10-30 s and thawings of double the freezing times. No anesthesia was required. All lesions had disappeared completely 2-4 weeks after one or two treatment courses of cryosurgery. In all cases, neither scarring nor recurrence was noted during the 6 months to 5 years of follow-up.

Effect of experimental disc perforation in sheep temporomandibular joints

The effect of surgical perforation of the disc on intra-articular morphology was examined using sheep. Eight sheep had bilateral perforations and 2 animals were used as controls. After 8 months the sheep were killed and the joints examined radiologically and histologically. Osteophytes were seen on all the condylar radiographs. Histologically, there were proliferative changes in both the condylar and temporal surfaces adjacent to the disc perforations.

Kabuki make-up syndrome (Niikawa-Kuroki syndrome) with cleft lip and palate

Kabuki make-up syndrome (Niikawa-Kuroki syndrome), recognized in Japan in 1981, is characterized by mental and growth retardation with specific craniofacial malformation such as lower palpebral eversion and depressed nasal tip. In this paper we describe a case associated with cleft lip and palate. Attention should be paid by maxillofacial surgeons to this syndrome, since 41% of the cases have been associated with cleft lip and palate (Niikawa et al., 1988; Tonoki and Niikawa, 1988).

The effect of occlusal loss on normal and pathological temporomandibular joints: an animal study

The effect of unilateral posterior malocclusion on temporomandibular joint intra-articular pathology was studied in sheep. In Group I, osteoarthritic changes were induced in the left temporomandibular joint by gentle scraping of the articular surface (Ishimaru and Goss, 1992). Group II had the same procedures as Group I, with concurrent extraction of all the left maxillary posterior teeth. Group III had a different osteoarthritic precondition in the left temporomandibular joint, allowing synovial fluid to contact the condylar marrow (Ishimaru et al., 1992). Group IV had the same procedure as Group III, with concurrent extraction of all the left maxillary posterior teeth. Group V had unilateral maxillary molar teeth extraction in the left side. At 3 months, the animals were sacrificed and the joints examined histologically. There were no significant differences between normal control joints and those with unilateral tooth extraction (Group V). Similarly the degree of osteoarthritic change was the same between Groups I and II. Significant differences (p < 0.05) were seen between Groups III and IV with tooth extraction increasing the osteoarthritic effects. Hence it was concluded that in sheep, malocclusion had no effect on the normal temporomandibular joint and on one type of experimental osteoarthritis, but accelerated osteoarthritic change in another model.

Effect of marrow perforation on the sheep temporomandibular joint

The effect of surgically perforating the mandibular condyle to allow synovial fluid to contact the marrow was examined in 5 sheep temporomandibular joints. The surgical defect showed replacement of the marrow with fibro-osseous tissue and subcortical cysts. A vertical, central osteophyte emerged from the perforation, causing attenuation or perforation of the disc and temporal surface proliferation. These changes were radiographically and histologically similar to advanced osteoarthritis. This supports the concept that intraarticular micro or macrofracture may result in osteoarthritis.