In order to study the initial corrosive changes of dental casting alloys in the mouth, the condition and composition of the proximal surface of the class II inlay were analyzed by the scanning electron microscope (SEM) and the electron probe microanalyser (EPMA) . These analyses on the same small areas of the proximal surface were carried out every week for four weeks. The results were compared with the condition and composition of the pre-placement in the mouth, and also with the data from former studies. 1. Changes observed in the 7OAu-3Pt-3Pd-lOAg-14Cu alloy (Au-alloy) were slight in comparison to the other alloys in this experiment, both on the surface condition and composition. 2. The 12Au-45Ag-2OPd-18Cu alloy (Pd-alloy) appeared to be stable in the mouth, but the changes were greater than that of the Au-alloy. 3. The Au- and the Pd-alloys appeared to be stabler after hardening heat treatment. 4. The greatest change was observed in the 65Ag-22Sn-13Zn alloy. 5. Little change was found in the 72Ni-19Cr-6Si alloy by visual inspection, but the dendritic structure was observed by SEM. 6. Almost all these changes of the alloys in this study showed somewhat greater changes than those observed in the conventional basic immersion tests of alloys.
It has been recognized that metallothionein (MT) is a low molecular-weight protein and can be induced by heavy metals in several organs. Most studies on MT focus on the liver and kidney, and little is known about MT in the bone marrow. In the present study, the characterization of the MT-like protein in bone marrow of rabbits was investigated after the injection of CdCl2. A dose of 8×10-5 mol/kg CdCl2 was injected subcutaneously into Japanese White Rabbits (male, 3.5kg) for five days. Twenty-four hours after the last CdCl2 injection, the bone marrow, liver and kidney were removed immediately and frozen. The fractions of metal-binding protein were obtained by gel filtration (Sephadex G-75) of cytosol from the tissues of Cd-treated rabbit. They were heat-stable and low molecular-weight (under 10 kDa) proteins. They had high absorption at 250 nm. These observations suggest that the injection of CdCl2 induced MT-like protein in bone marrow.
The purpose of this study was to polish electrolytically a large maxillary denture baseshaped titanium specimen with non-aqueous electrolyte. The test specimen was prepared by bending a sheet of titanium plate. An additional cathode was made by cutting off part of a cylindrical cathode. The effects of the shape and position of the additional cathode were investigated. Selected factors of the additional cathode were as follows : the connecting point between the additional cathode and the cylindrical cathode, the end position of the additional cathode, and the distance between the additional cathode and the titanium specimen. An acceptable polished titanium surface was obtained when the connecting point was below the electrolyte surface, the end position of the additional cathode was at a similar level to the bottom of the specimen, and the distance between the additional cathode and the specimen was 10 mm.
Influences of tooth contact patterns during mandibular retrusion on the terminal jaw relation (TJR) of habitual closures were investigated on five subjects. A maxillary stabilization splint with steep retrusive contacts was fabricated and applied to each subject for one week in the first series of this experiment. In the second series, steepness of the retrusive contacts was reduced and the splint with flat occlusal surface was applied. After each series, subjects were asked to perform habitual closures with an intraoral central bearing device and their TJR was recorded. The results were as follows: 1. TJR was influenced by the tooth contact pattern during mandibular retrusion. 2. TJR recorded after the second series tended to be more posterior than that after the first series. 3. It was suggested that the position of the condyle might change posteriorly with flatter retrusive contacts. 4. These results suggest the necessity of appropriate tooth guidance during mandibular retrusive movements for the dentulous subjects.
Children with trauma visit frequently the department of oral and maxillofacial surgery. The treatment for injured permanent teeth is different from that for injured deciduous teeth. We have experienced a case of a 9-year-old boy with an injured unerupted immature permanent tooth with tooth crown fracture. When the tooth erupted gradually, fractured pieces were removed three times, and indirect pulp capping was performed. Three years after the injury, eruption was almost completed and pulp was alive, even though the dental roentgenograph showed obliteration of the crown pulp cavity.
Recently in the field of clinical orthodontics, there has been increased interest in the relationship between jaw and head position, sleep apnea, and equivocal symptoms occurring in head, neck and shoulder. It has already been determined that a relation exists between head posture and mode of breathing. Since the craniof acial skeleton is supported by the cervical, thoracic and lumbar vertebrae, the head position might have some biomechanical connection to total body posture. Therefore, an integrated system of examining jaw position, head position and body posture is being developed.