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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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Dentistry. All rights reserved.