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Effect of the Denture Cleanser and Gargle on the Magnetic Attachment

Lin-Jin, Naomasa Sawada, Akio Asano, Makoto Sakai, Masatoshi lwahori,Mutsuo Yamauchi and Tooru Nagasawa


Recently, magnetic attachment is widely used in Japan. However, clean method for magnetic attachment has not been established.

In this study, the effect of chemical cleaning agent such as denture cleanser and gargle on the magnetic attachment was investigated.

Two kinds of magnetic attachment, HicorexTM (Hitachi Metals) and MagifitTM (Aichi Steel Co. Ltd), were immersed into denture cleanser, povidone iodine and high acid water for 4 weeks. The magnetic attachments were observed with a metal microscope before and after immersion. Surface roughness and attractive force were also determined, and an EPMA analysis of keepers was performed.

Although a haziness was observed on the surface of magnetic attachment, surface roughness, attractive force and electron micro-probe analysis were not affected by immersion.

These results suggested that denture cleansers and gargles don't have an affect on the magnetic attachments.


Key Words : Magnetic attachment, Denture cleanser, High acid water, Surface roughness, Attractive Force

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Effect of the Beneficial Ingredients Contained in Dentifrice on the Keeper of Magnetic Attachment

Naomasa Sawada, Akio Asano, Makoto Sakai, Mutsuo Yamauchi and Tooru Nagasawa


There are some beneficial ingredients contained in dentifiice such as fluoride, which is known to affect the surface properties of pure titanium. Because the keepers of magnetic attachments are fixed to the teeth, the effects of the beneficial ingredients contained in dentifrice on these devices need to be studied. In this study, we investigated whether the beneficial ingredients contained in dentifrice influence the keepers of magnetic attachments.

Two kinds of magnetic attachments, HicorexTM, (Hitachi Metals) and MagifitTM (Aichi Steel Co. Ltd. ) were selected for the study. The keepers of these attachments were immersed for 4 weeks in nine formulations of liquid dentifrice. The keepers were observed with a metal microscope before and after immersion. Surface roughness and attractive force were also determined, and an EPMA analysis was performed.

There were no significant changes in the surface roughness or attractive force. There were no new products detected on the surfaces of the keepers by EPMA analysis.

These findings indicated that none of the beneficial ingredients contained in dentifrice have any influence on keepers of magnetic attachments.


Key Words : Magnetic attachment, Dentifrice, Beneficial ingredients, Surface roughness, Attractive force

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Questionnaire Survey of the Patients' First Impressions on Magnetic Attachment

Kazutoshi Furukawa and Kanji Ishibashi


The purpose of this study was to understand a patients' first impressions on the magnetic attachment introduced to patients in our clinic by means of questionnaire survey.

From September 1992 to June 1998, magnetic attachments were applied to the dentures of 41, 36 of the patients (20 males and l6 females ; mean age of 68. 2 years) cooperated with the survey.

The results were as follows :

l) Evaluation of the satisfaction of patients using dentures with magnetic attachments was useful.
2) According to the answers from the patients to the questionnaires,the image for the magnetic attachment was obscure.


Key Words : patients' first impressions, questionnaire survey, magnetic attachment

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Dental Casting of Magnetic-Stainless-Steel (Investment)

Kojiro Aida, Katsunori Haoka, Taro Kanno, Kohei Kimura, Yukyo Takada, Osamu Okuno and Takafumi Nakayama


Crowns and bridges made of removable magnetic material are being developed with Fe-Pt magnetic alloy for outer crowns and magnetic-stainless-steel for inner crowns, respectively. While basic research on the casting of outer crowns has been carried out, nothing has been done on the use of magnetic-stainless-steel for dental casting inner crowns. The use of magnetic-stainless-steel for dental casting is, however, anticipated because it allows for the preparation of retainers for any configurations as well as the application of preformed magnetic attachments.

In this study, with regard to the preparation of retainers, basic research on the possible use of magnetic-stainless-steel for dental casting was carried out.

Six commercially available founding materials were examined in terms of their reactions to and the resulting surface roughness of SUS447J1, a magnetic-stainless-steel widely used in clinical practice for retainers of preformed magnetic attachments. Furthermore, the castability of those with good reactions and surface roughness was measured.

The results show that the founding material TitavestCB exhibits the best surface roughness and that its castability is as good as that of commercially available Co-Cr alloy.

This study suggest the possibility of using magnetic-stainless-steel for dental casting.


Key Words : magnetic stainless steel, dental casting, crowns and bridges, surface roughness, castability

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Effects of a Time-Varying Magnetic Field on Acetylcholine-Induced Transient Increase in Intracellular Ca2+ in Cultured Chromaffin Cells

Ki Ho Park, Toshitaka lkehara, Hisao Yamaguchi, Hitoshi Houti, Kazuo Yoshizaki, Yohsuke Kinouchi and Hiroshi Miyamoto


A transient increase in the intracellular Ca2+concentration ([Ca2+]c) occurred by adding O. 1mM acetylcholine (ACh) in bovine adrenal chromaffin cells. We studied the effects on the increase in [Ca2+]c during exposure to a magnetic field varied between 0.07 and 1.51 T at an interval of 3 sec. The increase in [Ca2+]c was unaffected by 2 hr-exposure in the normal medium, but was inhibited by30min-exposure in a Ca2+-free medium, and the effect continued for 4 hr. The increase in [Ca2+] c in the Ca2+-free medium was smaller than that in the normal medium. The similar results were obtained by addingl0-5M nicotine to the normal medium. Catecholamine (CA) secretion from the cells induced by ACh was intact when exposed to the magnetic field in the normal medium, where as it was inhibited in the Ca2+-free medium. CA secretion in this medium was less than that in the normal medium. These results lead to conclusions : magnetic field-exposure inhibits Ca2+ release from the intracellular Ca2+ stores stimulated via muscarinic ACh receptor but not via nicotinic ACh receptor, and inhibition of CA secretion by the exposure is due to the inhibition of Ca2+ release.
Key Words : adrenal chromaffin cells, time-varying magnetic field, acetylcholine, intracellular Ca2+, nicotine

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Analyses of Induced Currents in the Periodontium by ELF Magnetic Fields as a Basis of Alveolar Regeneration

Yasuhiro Fukui, Ki Ho Park,Yohsuke Kinouchi, Keiko Hosokawa,Toshitaka lkehara, Hisao Yamaguchi and Kazuo Yoshizaki


It has been reported that ELF (Extremely Low Frequency ; typically 50 or 60Hz) magnetic fields increase collagen syntheses of cultured osteoblasts significantly at an induced current level of 7 mA/m2. This effect may be applied to alveolar regeneration. The objective of this study is to determine ELF magnetic exposure conditions to induce the above effective currents in the periodontium. Induced currents for canine and first molar models in the mandible are analyzed by a finite element method. As a result, it has been found that :

l) Induced currents circulate mostly in the periodontium.
2) Magnetic fields applied in the mesial-distal direction induce larger currents.
3) Induced currents for both models are almost the same.
4) Magnetic fields of 10 to 20mT may be required to induce effective currents. This can be made possible by use of either electro or permanent magnets.


Key Words : ELF magnetic field, finite element analysis, induced current, periodontium, alveolar regeneration

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Analyses of Magnetic Retention Characteristics for Cylinder Types of Magnetic Attachment

Yoshinori Tegawa and Yohsuke Kinouchi


It is required, on one hand, to develop a magnetic attachment which has large forces and restoring forces to resist the reduction of magnetic retention due to the deformation of the alveolar ridge and dentures. Here we propose four types of cylinder type magnetic attachments. Theoretical analyses show that some of them have large forces and large restoring forces as compared with those of usual attachments on the market. Therefore, the cylinder type magnetic attachments proposed here will supply useful retention characteristics in magnetic prostheses.


Key Words : magnetic attachment, cylinder type, denture, restoring force, magnetic force

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Dynamic Analysis of a Magnetic Attachment using Finite Element Method - Comparison of the two dimensional analysis with the three dimensional one -

Yoshinori Nakamura, Yoshinobu Tanaka, Takashi Ishida, Tatsuhiko Masuda,Yoshinori Desaki, Kenji Tsuda, Sachiko Okazaki,Takeshi Kanazawa.Tomohiko Ishigami and Kiyohiko Nomura


A three dimensional analysis is basically an appropriate approach for magnetic analysis which is indispensable to make a reasonable design of a magnetic attachments. But making models and analyzing them is complicated and much time, so it is not feasible to use a three dimensional model for all investigations. Therefore, it is very important to recognize the precise value from the point of view of praticality depending on each purpose. From this investigation, some very valuable results of the two dimensional analysis were confirmed. It also was made clear that there is a dangerous possibility of making an error when the air gap between the magnetic assembly and the keeper is increased.


Key Words : FEM method, magnetic attachment, magnetic attractive force

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Effect of a Magnetic attachment on the Bending Strength of the Acrylic Resin Denture Base

Norie Nozaki, Yoshinobu Tanaka, Yoshinori Desaki, Yasuo Kishimoto, Tohru Sato, Yoshinori Nakamura, Nobuhiro Hasegawa and Shigeo Tanaka


The denture base of an over-denture installed with a magnetic attachment tends to be fragile due to insufficient cross sectional area at the said portion. The purpose of this paper is to investigate the breaking point of the magnetic denture base due to its shape.

The results suggested from our three-point bending test on various shapes of resin blocks which simulate clinical denture bases are as follows :

1. The thickness of the resin layer above the magnetic assembly is very important to ensure the denture base strength.
2. Cutting the denture base at the abutment site for hygienic reasons weakens the strength.
3. Application of a metal bonding agent on a magnetic assembly works well to improve the strength.


Key Words : magnetic attachment, bending strength, denture base strength, metal bonding agent

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