Hideo Tsutsui

Studies on the Sm-Co Magnet as a Dental Material

The Sm-Co magnet has superior and convenient magnetic properties as compared with conventional ones used hitherto in prosthesis, and even very small pieces can provide the force necessary in dentistry. Also, the magnet has high corrosion resistance and is innocuous to tissues. Therefore, it can be used as a dental material, overcoming the limitations in past applications.

Materials Science Cytotoxicity of Pd-Co Dental Casting Ferromagnetic Alloys

The biocompatibility of three kinds of Pd-Co dental casting ferromagnetic alloys was assessed in a toxicity test in vitro. The test showed that the Pd-Co binary alloy may have weak cytotoxicity, while the Pd-Co-Cr and Pd-Co-Ni ternary alloys may be less cytotoxic. The Pd-Co-Ni alloy was least cytotoxic of the three.The biocompatibility of three kinds of Pd-Co dental casting ferromagnetic alloys was assessed in a toxicity test in vitro. The test showed that the Pd-Co binary alloy may have weak cytotoxicity, while the Pd-Co-Cr and Pd-Co-Ni ternary alloys may be less cytotoxic. The Pd-Co-Ni alloy was least cytotoxic of the three.

Pd-Co Dental Casting Ferromagnetic Alloys

Three kinds of Pd-Co alloys have been newly developed. Their magnetic and physical properties and corrosion resistances have been examined. As a result, it was found that they are available as the dental casting ferromagnetic alloy which can be used in combination with Sm-Co magnets, overcoming such problems as non-castability and brittleness.

Sectional prostheses connected by samarium-cobalt magnets

Large acquired defects with undercuts can be restored with sectional prostheses. Sections of the prosthesis can be connected with small Sm-Co magnet pairs. The advantages of Sm-Co magnets are that (1) sections of prostheses can be connected by magnets less than 1 cm in size, (2) they can be embedded in thin sections of acrylic resin, (3) they are easy to place, (4) insertion is easy (magnetic attraction enhances), (5) hollow obturators can be used, and (6) tissue undercuts can be used for additional retention of prostheses.

Study on abnormalities in the appearance of finger and palm prints in children with cleft lip, alveolus, and palate

The aetiology of abnormalities in the appearance of finger and palm prints in children with cleft lip, alveolus, and palate was examined by comparing the frequencies of abnormalities in hereditary cases and sporadic cases, and those in hereditary cases with those in their parents. The following results were obtained: Comparison of hereditary cases and sporadic cases. Abnormalities in the appearance of finger and palm prints were greater in hereditary cases than in sporadic cases. Abnormalities in the appearance of finger and palm prints were greater in parents of hereditary cases than in parents of sporadic cases. The rate of agreement in the appearance of finger and palm prints between parents and children was greater in hereditary cases than in sporadic cases. Comparison within hereditary cases. Abnormalities in the appearance of finger and palm prints were greater in affected children when one of the parents was affected (gamma = 1/2) than when both parents were normal (gamma = less than 1/2). Abnormalities in the appearance of finger and palm prints were greater in parents, one of whom was affected, than in normal parents. The rate of agreement in the appearance of finger and palm prints of parents, one of whom was affected, and their gamma = 1/2 children cases was higher than of normal parents and their gamma = less than 1/2 children. It was concluded that the above results could be explained by multifactorial inheritance.

Optimization and Design of Permanent Magnet Devices for Retaining Dental Prosthetic Appliances

Attraction between a pair of rare earth-cobalt magnets is very useful for retention of dental prosthetic appliances. In these applications, the space available for embedding magnets is very narrow. Therefore, the magnets must have those optimum dimensions which cause the mximum attraction. The optimum dimensions are calculated for a rectangular or disk magnet pair utilizing the axial or radial attraction. In order to maximize the axial attraction of a magnet pair in small separation, the rectangular magnet must be slender and the square or disk magnet must have a size ratio of about OA, which is defined as the ratio of thickness to length of edge or diameter of the magnet. In the case of radial attraction, the optimum disk magnet has a little larger size ratio, e.g., about 0.55 in zero separation. Based on these theoretical analyses, the method of designing the optimum magnets with a required attraction is proposed.