[an error occurred while processing this directive]Magnetic Line of Force and Its Magnetic Application to Dentistry
Hajime Yamada, Tsutomu Mizuno*, Seiichi Watanabe**, Makoto Utsuno***
Shinshu University Doctoral International Collaboration Institute
*Faculty of Engineering Shinshu University
**Nagano National College of Technology
***Graduate School of Science and Technology Shinshu University

The paper deals with fundamental property of magnetic line of force and operation principles of Magnetic sensors and eddy current sensors which are acted by the magnetic line of force. Mechanical models of tooth movement are analyzed based on the past research results.
Useful magnetic sensors and eddy current sensors in the magnetic application in dentistry are surveyed. The paper explains each measuring range, resolution, size and production companies or small-sized SQUID, magneto impedance sensor and Hall-sensor. It is listed up the principle or measurement and the characteristics of displacement sensors, velocity sensors, acceleration sensors and pressure sensors. The paper also suggests relationship between the saliva and the permanent magnet or the magnetic attachment. Present research results of "new tracking systems of jaw movement" by two research groups are Introduced. It is classified five Japanese Patents related the chewing counters in 1993-2000, the key Point of the chewing counter development also describes in the paper.

Key Words: Magnetic application in dentistry, Magnetic line of force, Magnetic force, 3-dimensional measurement, Chewing counter

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A Prosthetic Design Guideline for Effective Usage of Magnetic Attachments -Application to Restorations Supported by Implants-
Jyoji Tanaka*,**, Kazumasa Hoshino**
* Clinical Implant Society of Japan
** Department of Anatomy, Nihon University School of Dentistry at Matsudo

A magnetic attachment is an excellent retaining device with various benefits. Due to the unique retaining mechanism using "magnetic energy", however, its maximum potential cannot be attained if used based solely on prosthetic concepts proven for conventional flexible and rigid support restorations. For this reason, a design guideline has been developed by classifying the functional roles of magnetic attachments into Type R for retention only, Type SR for support and retention and Type BSR for bracing, retention and support. Further, the practical design chart we have developed, focusing on implant-supported overdentures, based on the guideline has led us to successful treatment outcomes. The guideline and the design chart have demonstrated their effectiveness in prosthetic restoration using the MACS System (Magnetic Attachments of a Cap Shape), a magnetic attachment system having high compatibility with the classification mentioned above. "Universal Support" is the new prosthetic policy we proposed, in which the highest priority is placed on freeing the patients from feelings of inadequacy due to tooth loss. Magnetic attachments have been indicated to be the optimal retaining device for Universal Support restorations.

Key Words: Magnets , Implants , Prosthetic design , MACS System , Universal Support

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Influences of the Heat Treatment for Magnet Assemblies with or without Keepers on Attractive Force of Magnetic Attachments
Kazuo Nakamura, Masato Kotake*, Hiroshi Mizutani**
Organized Center or Clinical Medicine, international University or Health and Welfare
** Removable Prosthodontics, Department or Masticatory Function Rehabilitation, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University

The property of magnets incorporated in magnetic assemblies are affected by surrounding environments i.e. airgap. The purpose of this sturdy was lo evaluate the effect of the airgap (with or without keepers) on the attractive force or magnetic attachments after heating procedures. 5difrerent sized HICOREX SLIM (Hitachi Metals Ltd), which consisted or the Nd-Fe-B magnet were used in this study. The results were as follows.
1.Magnetic assemblies heated with keeper. Attachments forces remained stable until they were heated at 190 degrees C. The difference of their sizes did not affect their heat-stabilities.
2. Magnetic assemblies heated without keepers. Attractive forces remained stable until they were heated at 120 degrees C. (HICOREX SLIM 4513,4013), 130 degrees C. (HICOREX SLIM 3513), 150 degrees C. (HICOREX SLIM 3013,2513). Magnetic attachments became wider in size, their heat-stabilities dropped.

Key Words: Dental magnetic attachment, Air gap, Heat resistance

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Expression of Gap-magnetic force Characteristics of Magnetic Attachments
Yoshinori Tegawa, Yohsuke Kinouchi*
School of Health Sciences, The University of Tokushima
*Faculty of Engineering, The University of Tokushima

Several different types of magnetic attachment have being used together for retention of the oberdenture in ordinary clinical practice. Evaluating the retention characteristics of such magnetic attachments may be very complex. For analysis of magnetic retention , it is convenient to represent the retention characteristics by a simple expression. The expression is derived here and applied to each magnetic attachment. Functional efficiency of various magnetic attachments is also compared With each other.

Key words: Magnetic attachment, Prosthodontics, Numeric analysis, Attractive force

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The laboratory procedure of magnetic attachment by Direct Bonding method

Tomokazu Hirano, Kouichi Sugiyama, Yukihiro Mizuno, Fujio Tsuchida* Michio Motonaga* Toshio Hosoi*

Dental Technician Training Institute Tsurumi University School of Dental Medicine
*The First Department of Prosthetic Dentistry, Tsurumi University School of Dental Medicine

Dental laboratory techniques for direct bonding method, which will solve some of the problems associated with casting and make full use of the attachment magnetic property were investigated in this study. The following results were obtained using an ultra-precision finishing film and cover glass cementing technique.
1. Adhesive resin cement can be light-cured through the cover glass.
2. It is possible to obtain a same finish plane between the surface of the adhesive resin cement and the keeper.
3. The smooth surface of the cover glass is transferred to the surface of the adhesive resin cement.
4. The keeper surface can be fabricated without overflow resin cement and scratch.

Key words: Magnetic Attachment, Root Cap, Cover Glass, Adhesive Resin Cement, Direct Bonding Method

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