The Journal of Osaka University Dental School最新文献

In this study, the activities of the two external glossal muscles, Genioglossus (Gg) and Styloglossus (Sg), related to respiration were examined through the electromyography (EMG) in dog. During quiet breathing, no phasic respiratory activity were observed in either muscle. With hypercapnic condition induced by closed rebreathing respiratory system, both Sg and Gg showed phasic respiratory activities in respiration period. At first inspiratory EMG activity was observed from Sg (PaCO2 > 50 mmHg), then after a while from Gg (PaCO2 > 55 mmHg). NaCN injection bilaterally to the carotid body enhances the inspiratory ENG activities in both muscles. Sg was more sensitive than Gg to respiratory stimulation such as hypercapnia or NaCN injection.

The effects of nerve fibers on bone formation during tooth movement were examined using eight rabbits with denervation of inferior alveolar nerve (IAN). IAN on one side for all the animals was denervated and and sham operation was performed on the other side of denervation. The distance of tooth movement on the denervated and sham operated sides was very similar and 1.20 +/- 0.17 and 1.24 +/- 0.12 (mean +/- S.D. mm), respectively. From the fluorescent observations, the denervated and sham operated sides in the animals without tooth movement i.e. control group showed similar morphology. The animals with tooth movement i.e. experimental group showed significant new bone formation than the control group. However, the amount of new bone formation on the denervated side was less than the sham operated side. It was suggested that the nerve fibers might play some roles on bone formation during the tooth movement.

In this study the mechanisms controlling the biomechanical relationship between form and function in the temporomanidbular joints were investigated using two-dimensional finite element analysis and optimization theory. Factors investigated included morphology and occlusion, the latter being an important attribute of this system. Results indicate that change in frontal condyle head morphology was closely related to the occlusion condition.

In order to investigate the clinical characteristics of patients with condylar atrophy, we examined 146 patients with craniomandibular disorders using tomography. No statistical difference in occurrence of the condylar atrophy between males and females was observed. Patients with condylar atrophy was younger than those without condylar atrophy. And, condylar atrophy was closely related to craniomandibular disorders, especially to internal derangement or osteoarthrosis of the temporomandibular joint.

A patient with severe habitual dislocation of the bilateral temporomandibular joint involving epilepsy was operated using porous hydroxylapatite blocks as intervention material. The patient was followed up for 4 years. He has been well without recurrence of dislocation or any complication. In this paper, we report the procedure and the relevant literature is discussed.

The purpose of this study is to determine the effects of heat treatment and soldering on the change of shape and mechanical properties of cobalt-chromium-nickel alloy wrought wire clasps. The change of distance between the tips of the clasp arm was measured and mechanical properties were examined using the bending test. The following results were obtained. 1) By heat treatment at 500-700 degrees C for 10 minutes, bending rigidity and deflection at the proportional limit of the clasp arm increased significantly (p < 0.01), while permanent deformation after the bending test decreased considerably (p < 0.01). Concerning the deformation of clasp arms by heating, the distance between clasp tips increased remarkably above 500 degrees C (p < 0.01). 2) These mechanical properties of clasp arms were improved both by electric resistance soldering with silver solder and by heat treatment at 500 degrees C for 10 minutes after soldering. From these results, it was concluded that electric resistance soldering and adequate heat treatment were very effective to improve the mechanical properties of the clasp arm, especially to increase the deflection at the proportional limit and reduce the permanent deformation.

Intramuscular hemangioma is a distinctly rare neoplasm originating within normal muscle. In the head and neck region, it occurs most frequently in the masseter muscle. Diagnosis of intramuscular hemangioma is extremely difficult because it is not encountered frequently and is often confused with salivary gland stone, parotid neoplasm or other tumors. In this report, a second case of intramuscular hemangioma of the digastric muscle and the diagnosis of this type of tumor in the early stage and the importance of its treatment are described.

We performed an experiment on adhesive strength between teeth and resin cements for porcelain laminate veneer. A compression shear test was performed using three types of resin cement in extracted human anterior teeth. In dentin, the effects of various surface treatment methods were also evaluated. All three types of resin cement showed high adhesive strengths to enamel, but low adhesive strengths to dentin that were less than 1/2 of those to enamel. Treatment of the dentin surface with both a surface treatment agent and primer significantly increased adhesive strength.

It is very important for design and construction of complete dentures to evaluate the condition of residual ridges of edentulous patients objectively and precisely. The authors have been developing a shape measurement system for residual ridges. In this study, the outline of the system is described and the accuracy of the system is evaluated. The system consists of a high precision laser displacement meter, a working table and its controller, and a personal computer. The working table, on which a plaster model is placed, can move until the end of the moving range at a speed of 0.7 mm/sec. The height of the plaster model was measured intermittently with a frequency of 7 points/sec. To determine the accuracy of this system, experimental plaster models, which simulated the simplified shape of residual ridge, were measured and analyzed. The measurement error was 2.5%, which seemed to be highly accurate. The accuracy of the measurement decreased with the darkness of the color of the plaster model.

Resin-Hydroxyapatite has been developed to take the advantages of bioactivity of hydroxyapatite (HAP) and plasticity of resin (Bis-GMA). It was composed of 75% HAP, 15% Bis-GMA and 10% quartz reinforced filler. Tested pellets of Resin-HAP as well as its constituents were implanted into subcutaneous connective tissue of femurs of adult dogs. Histological observation at 12 weeks postoperatively showed that each pellet was surrounded by the fibrous connective tissue almost free of the inflammatory cells. The thickness of the fibrous layer around HAP was relatively thin, while those around Bis-GMA and Resin-HAP showed some variance. Taking our previous data into consideration, it was suggested that Resin-HAP had bio-compatibility both in soft tissue and bone, although its long-term stability as well as its stability under function should further be examined.