Akiko Ohtsuka

Ectopic osteogenesis with biphasic ceramics of hydroxyapatite and tricalcium phosphate in rabbits

Porous calcium phosphate ceramics consisting of hydroxyapatite (HA) and tricalcium phosphate (TCP) with different HA to TCP ratio were implanted intramuscularly in rabbits for six months in order to carry out a comparative study on osteogenic activity of the ceramics. Bone formation was detected only in HT73 (HA to TCP ratio, 7-3) specimens. Other implants, HT28 (2-8) and HT010 (0-10), could not induce bone. After a six-month period of implantation, HT28 and HT010 implants showed obvious degradation of the implants changing their shape and size macro and microscopically. Microscopically, they showed aggregates of fine particles and appearance of multinucleated cells. However, HT73 implants was less degraded and could maintain their original structure macro and microscopically. This study showed that HT73 ceramics can induce bone in rabbit muscle tissue and it is considered that maintenance of porous structure, that is, degradation rate of the materials may be one of the affecting factors in ceramic-induced osteogenesis.

Efficacy of a mandibular manipulation technique in reducing the permanently displaced temporomandibular joint disc

PURPOSE The purpose of this study was to determine whether disc reduction occurred in patients with closed lock after mandibular manipulation (MM) and to analyze the factors that influenced the result. PATIENTS AND METHODS Two hundred fifteen patients with closed lock received MM. Of these, 74 patients (79 joints) were assessed by means of magnetic resonance imaging (MRI) for disc reduction. The results of the MRI were compared with the findings from the clinical and radiographic examinations. RESULTS According to the MRI assessment, only 18% (14 of 79) of the joints had successful disc reduction. The unsuccessfully treated joints had severe joint pain, disc displacement, condylar bone change, and disc deformity. CONCLUSIONS The results of this study suggest that successful reduction of the disc by MM is rare. They also suggest that MM is least effective in the advanced stages of internal derangement, when the disc becomes deformed.

Change of position of the temporomandibular joint disk with insertion of a disk-repositioning appliance

OBJECTIVE We report alteration of the temporomandibular joint disk and the condyle position through the construction of a mandibular full-coverage occlusal appliance (often referred to as a disk repositioning appliance). STUDY DESIGN Forty-five joints with displaced disks with reduction were available for the study. We assessed these joints for disk recapture and the change of disk position with insertion of the appliance using magnetic resonance imaging. RESULTS Of the 41 joints that had a recaptured disk with insertion of the splint, 25 slid in a posterior direction, although the amount of movement was negligible. No disk slid posteriorly in the joints without splint capture. CONCLUSIONS On the basis of our results, we conclude that many of the occasionally displaced disks might have moved backward with successful treatment involving a disk-repositioning splint. However, the amount of the movement was negligible.

Evaluation of disk capture with a splint repositioning appliance: clinical and critical assessment with MR imaging.

OBJECTIVE The purpose of this study was to evaluate disk repositioning clinically and through use of magnetic resonance imaging after the insertion of a disk repositioning appliance. STUDY DESIGN Seventy-four patients with 82 temporomandibular joints showing middle to late opening movement click and closing movement click near maximum intercuspation were treated with a mandibular full-coverage repositioning splint. These joints were assessed clinically and by means of magnetic resonance imaging for disk recapture. RESULTS According to clinical assessment, 75.6% (62/82) of the joints were treated successfully; no click was observed from the splinted mandibular position. When compared with the results of magnetic resonance imaging assessment, clinical assessment showed an accuracy rate of 91.5%, although the incidence of the false negatives was high (40%). CONCLUSIONS The results of this study showed that about 70% of reducing displaced disks were captured with use of the disk repositioning appliance. And it was also suggested that magnetic resonance imaging is helpful to evaluate disk repositioning therapy.