日 磁 歯 誌
J J M ag Dent
ISSN 0918-9629

日本磁気歯科学会雑誌

2021

Volume 30. Number 2

第三十巻 第二号
J J Mag Dent

日本磁気歯科学会雑誌

The Journal of the Japanese Societyof Magnetic Applications in Dentistry
Volume 30, Number 2

日本磁気歯科学会
21

The Japanese Society of Magnetic Applications in Dentistry
日本磁気歯科学会

J J Mag Dent vol. 30

No. 2

2021

The Journal of the Japanese Societyof Magnetic Applications in Dentistry
Volume 30, Number 2

Proceedings of the 20th International Conference
on Magnetic Applications in Dentistry

The Japanese Society of Magnetic Applications in Dentistry

J J Mag Dent vol. 30

No. 2

2021

The 19th International Conference on Magnetic Applications in Dentistry
The 19th International Conference on The Japanese Society of Magnetic Applications in
Dentistry organized by JSMAD was held on the Internet as follows;
Meeting Dates:
Friday, February 26 to Tuesday, March 16, 2021
Location:
JSMAD web site
http://jsmad.jp/international/20/
General Chair:Prof. Jun Takebe, Aichi-Gakuin University
Subjects:
Researches and developments related to dentistry and magnetism such as:Magnetic attachments for dentures

Orthodontic appliances using magnets

Measurement of jaw movement using magnetic sensors

Biological effects of magnetic fields

Dental applications of MRIOthersJ J Mag Dent vol. 30

No. 2

2021

Conference Committee
The Japanese Society of Magnetic applications in Dentistry
President of the Japanese Society of Magnetic applications in Dentistry
Dr. Yukyo Takada, Tohoku University
Vice-President of the Japanese Society of Magnetic applications in Dentistry
Dr. Masayuki Hideshima, Tokyo Medical and Dental University
Conference Secretary
Dr. Masatoshi Takahashi, Tohoku University
Conference Organizing Committee
Dr. Hideki Aita, Health Science University of Hokkaido
Dr. Masatake Akutagawa, The University of Tokushima
Dr. Tetsuo Ichikawa, The University of Tokushima
Dr. Shuji Ohkawa, Meikai University
Dr. Tetsuo Ohyama, Nihon University
Dr. Chikahiro Ohkubo, Tsurumi University
Dr. Tohru Kurabayashi, Tokyo Medical and Dental University
Dr. Hisashi Koshino, Health Science University of Hokkaido
Dr. Mineyo Sone, Meikai University
Dr. Jun Takebe, Aichi-Gakuin University
Dr. Joji Tanaka, Tanaka Dental Clinic
Dr. Fujio Tsuchida, Mami's Dental Office
Dr. Kazuo Nakamura, Sanno Hospital
Dr. Kazuhiro Nagata, The Nippon Dental University
Dr. Yuji Honda, Honda Shika Daiichi Shinryoujo
Dr. Eri Makihara, Kyusyu Dental University
Dr. Shinichi Masumi, Kyusyu Dental University
Dr. Shunsuke Minakuchi, Tokyo Medical and Dental Universit
Dr. Motonobu Miyao, Asahi University
Conference Arrangements Committee
Dr. Shunsuke Minakuchi, Tokyo Medical and Dental Universit
Dr. Masatake Akutagawa, The University of Tokushima
Dr. Shogo Ozawa, Aichi-Gakuin University
Dr. Hisashi Koshino, Health Science University of Hokkaido
Dr. Shuji Ohkawa, Meikai University
Proceeding Committee
Dr. Mineyo Sone, Meikai University
Dr. Hideki Aita, Health Sciences University of Hokkaido

J J Mag Dent vol. 30

No. 2

2021

Dr. Masatake Akutagawa, The University of Tokushima
Dr. Hirokazu Kumano, Aichi-gakuin University
Dr. Masatoshi Takahashi, Tohoku University
Dr. Shinya Nakabayashi, Nihon University
Dr. Shinichi Masumi, Kyusyu Dental University

Published by the Japanese Society of Magnetic applications in Dentistryc/oDental Clinic for Sleep Disorders (Apnea and Snoring)Tokyo Medical And Dental University, Dental Hospital
1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549 JAPANCopyright (c) 2021 The Japanese Society of Magnetic Applications in Dentistry
All right reserved. No part of this publication may reproduced, stored in a retrieval
system, or transmitted, in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without prior written permission from thepublisher.
B&W:

Ryuwa print
223-5, Fukawa, Kawagoe, Saitama 350-0831 JAPAN

Visit JSDMD Home Page for updates!
http://www.jsmad.jp/

J J Mag Dent vol. 30

No. 2

2021

The 21th International Conference on Magnetic Applicationsin Dentistry General Information
General Information
The Japanese Society of Magnetic Applications in
Dentistry (President: Yukyo Takada, Tohoku University)
is a scientific association founded in 1991 and is devoted
to furthering the application of magnetism in dentistry.
The 21st International Conference on Magnetic
Applications in Dentistry organized by JSMAD willtake place on the Internet as follows.
Meeting Dates:
Monday, February 21 to Monday, March 7, 2022
Location:
JSMAD web site:
http:/ /jsmad.jp/international/21/
General Chair:
Clin. Associate Prof. Tetsuo Ohyama, Nihon University
Executive Committee Chair:
Assist Prof. Hiroyasu Yasuda, Nihon University
Subjects:
Researches and developments related to dentistry andmagnetism such as:·Magnetic attachments for dentures·Orthodontic appliances using magnets· Measurement of jaw movement using magnetic
sensors·Biological effects of magnetic fields·Dental applications of MRI·Others
Registration Infomation
Registration:
Send e-mail titled "registration for 21st international
conference" with your Name, University or Institution,
Postal address, Phone, Fax and E-mail address toconference secretariat.
Registration Fees:
No registration fees. Anyone who is interested inmagnetic applications in dentistry can participate in theconference via the Internet. Publishing Charge for
Proceedings:
After the conference, the proceeding will be published.
The publishing charge is 10,000 yen per page. (Nocharge for invited paper.)Deadlines:
Entry: January 24, 2022
Poster submission: February 7, 2022
Entry:
Send Title and Abstract within 200 words with yourRegistration.
Paper submission:
Please send papers in Microsoft Word format to theconference secretariat by E-mail. All contents should be
written in English. No multi-byte character, such as
Japanese Kanji, should be contained. A template file canbe obtained from the conference web site. Web
presentations for the conference will be produced by thesecretariat from the paper. The secretariat will not makeany correction of the paper even miss-spelling,grammatical errors etc. Alternative format files are
acceptable. Please contact to the secretariat for moredetailed information.
Discussion:
Discussions will be done using a bulletin board on
JSMAD Web Site via the Internet. The authors should
check the board frequently during the meeting dates. Ifquestions or comments on your presentation are posted,
please answer them as soon as possible.
Notice to Contributors:
Freely-given informed consent from the subjects or
patients must be obtained. Waivers must be obtained forphotographs showing persons.
Note:
Copyright of all posters published on the conference will
be property of the Japanese Society of Magnetic
Applications in Dentistry. Copies of the posters will bemade and transferred to JSMAD web site for continuouspresentation after the meeting dates.
For further information,
send e-mail to conference secretariat.
Conference Secretariat

Hiroyasu Yasuda, Nihon University
E-mail: jsmad31@gmail.com
Tel: +81-3-3219-8144

Guidelines for Presentation

Visit JSMAD Home Page for updates!
http://jsmad.jp/

J J Mag Dent vol. 30 No. 2

2021

Contents
Session 1

Chair: Shogo Ozawa (Aichi-Gakuin University)

1. A case report of a removable denture using magnetic attachments for a missing mandibular molar with adecreased occlusal vertical dimension followed up for 9 years
M. Sone，D. Matsumoto, N. Koyama, F. Narumi, T. Matsukawa, S. Uchida, S. Somekawa, K. Takahashi,
M. Suzuki, Y. Miyoshi, D. Sakamoto, K. Okamoto, and S. Ohkawa・・・・・・・・・・・・・・1
2.

A case report of removable partial denture applied magnetic attachment and zirconia framework for a patient witha decreased occlusal vertical dimension
TAKEYAMA J, SUZUKI Y, HARADA N, SHIMPO H, KURIHARA D, MUTOH R, OHKUBO C・・・・5

3.

Clinical evaluation of implant overdentures using magnetic attachment: retrospective study
Takayama H，Suzuki Y，Kurihara D，Maruo R，Shimpo H, Ohkubo C・・・・・・・・・・・9

Session 2 Chair: Hideki Aita (Health Sciences University of Hokkaido)
4. Effect of crosshead speed on retentive force measured using a device specified in ISO 13017:2020
M. Takahashi, G. Togawa, M. Kanyi, H. Yamaguchi and Y. Takada・・・・・・・・・・・・・・12
5.

Mechanical consideration of implant support in removable partial denture design applied by a magnetic
attachment using three-dimensional finite element analysis
Kumano H, Kanbara R, Fujinami W, Matukawa R, Ando A, Hata M, Kojima N, Yoshioka
F, Ozawa S, Nakamura Y, Nakamura H, Shoji K and Takebe J・・・・・・・・・・・・18･

Appendix
How to Write the Proceedings?
for International Conference on Magnetic Applications in Dentistry・・・・・・・・・22

1

A case report of a removable denture using magnetic attachments for a
missing mandibular molar with a decreased occlusal vertical dimension
followed up for 9 years
M. Sone㸪D. Matsumoto, N. Koyama, F. Narumi, T. Matsukawa, S. Uchida, S. Somekawa, K. Takahashi,
M. Suzuki, Y. Miyoshi, D. Sakamoto, K. Okamoto, and S. Ohkawa
Division of Removable Prosthodontics, Department of Restorative and Biomaterials Sciences, Meikai
University School of Dentistry

Abstract
This case report describes our establishment of an appropriate OVD for a patient with a decreased
OVD to restore the aesthetics and function by the use of magnetic attachments.
As a definitive prosthesis, a maxillary removable overlay denture with coping-type magnetic
attachments and a horseshoe plate as the major connector was fabricated, and a mandibular removablepartial denture with an extracoronal-type magnetic attachment was also fabricated.
Nine years after the denture setting, the definitive prosthesis has been used without serious problems,
and the magnetic attachment has no clinically significant loss of retention.

Introduction
To maintain a harmonious craniofacial system, it is essential to establish an appropriate occlusal
vertical dimension (OVD). 1) This case report describes our establishment of an appropriate OVD for apatient (missing mandibular molar) with a decreased OVD to restore the aesthetics and function by theuse of magnetic attachments.

Clinical History
The patient, a 59-year-old female, complained of aesthetic dissatisfaction and masticatory dysfunction.
The patient had a partially edentulous maxilla (Eichner classification :B3, Disease type classification at
Japan Prosthodontic Society :1-Ϩ LevelϨand Occlusal-triangle :area A) (Figs.1, 2, and 3). All fixed
prostheses were failed restorations with marginal discrepancies and damaged by caries and periodontal
disease. The patient refused to wear a mandibular removable partial denture because of dissatisfaction
with a visible metal clasp on the anterior teeth. She was diagnosed with infraocclusion by analysis of
OVD.

Fig.1 Intraoral view at the first visit

Fig.2 X-ray photographs at the first visit

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Fig.3 Periodontal disease examination at the first visit

Treatment Procedure
First, the prosthesis with the marginal discrepancy was removed (Fig.4), and temporary restorations
were placed. The 3 and 12 teeth were extracted because of severe caries. After preprosthetic treatment,
the OVD was increased by the use of the treatment denture, and the patient obtained an adequate
occlusal relationship (Figs.5 and 6).

Fig.4 Intraoral views ofremoving the prosthesis

Fig.5 Occlusal reconstructionof denture

Fig.6 Intraoral views ofinserting temporary
restorations

As a definitive prosthesis, a maxillary removable overlay denture with coping-type magnetic
attachments and a horseshoe plate as the major connector was fabricated , and a mandibular removablepartial denture with an extracoronal-type magnetic attachment was also fabricated. The magnetic
attachments used in this case report were GIGAUSS C400® (GC, Japan). The keepers of the magnetic
attachment and magnetic assemblies were fixed with adhesive resin cement (Multilink® Automix,
Ivoclar Vivadent, Liechtenstein) (Figs.7 and 8). Figure. 9 shows an intraoral view of the definitive
prosthesis.

Fig.7 Maxillary removable overlay denture
and the magnetic attachment

Fig.8 Mandibular removable denture
and the magnetic attachment

3

Fig.9 Intraoral view with definitive prostheses

Outcome of Treatment
Presently, 9 years and 6 months have passed since the definitive prosthesis was set(Fig.9). During thattime, maintenance was initially carried out every month; however, after 3 years, at the request of theperson, it was reduced to every 3 months. The results of the most recent treatment of periodontal disease
examination showed no significant change in both periodontal pockets and tooth mobility compared tothe end of the definitive prostheses. The results of examination during the most recent treatment of
periodontal disease showed no significant change in periodontal pockets or tooth mobility as comparedto the end of the definitive prosthesis setting. The results of dental X-ray photographs showedenlargement of the periodontal ligament cavity of the left support tooth from the middle of the mandible(Fig.10). In addition, gingival recession of #34 was recognized in the oral cavity, and significant bitewear of the artificial tooth of #35 was recognized (Fig.11). From the inquiry result that the remaining
part of the maxillary abutment tooth was biased to the left side and the habitual chewing side was on theleft, it was inferred that this was caused over time because the burden of the bite force was larger thanthat of the right side.

Fig. 9 Intraoral view with definitive
prosthesis at 9 years after treatment

Fig.10 X-ray photographs at 9 years Fig.12 Degradation over timeafter treatment

4

The elution amount of glucose in the masticatory function test 3 years after the operation was 121
mg/dl, but increased to 150 mg/dl after 9 years and 6 months (Fig.12).
Additionally, the score of OHRQoL using OHIP-142) decreased over time, and treatment results wereobtained with high patient satisfaction (Fig.13).

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Fig.13 Oral Health Impact Profile-14 for JapaneseConclusions
A magnetic attachment could be provided as a useful retentive appliance for alleviating patientcomplaints regarding aesthetics and function. It is difficult to maintain an ideal combination of aesthetics
and functionality because the design of a final prosthesis is complex. Therefore, continuous follow-up isnecessary with occlusal adjustment and relining of the denture base to prevent any reduction of the
OVD.

References
1.
2.

M. Sone, Y. Kawakami, F. Okutsu, T. Matsukawa, Y. Toyota, R. Negoro, S. Shimokawara, K.
Okamoto, and S. Ohkawa: A case report of Occlusal Reconstruction with Overdentures Using
Magnetic Attachments, JJ Mag Dent, 23(2), 1-3, 2014
Allen F, Locker D: A modified short version of the oral health impact profile for assessing
healthrelated quality of life in edentulous adults, Int J Prosthodont 15, 446-450, 2002.

5

A case report of removable partial denture appliedmagnetic attachment and zirconia framework for a patientwith decreased occlusal vertical dimension
TAKEYAMA J1, SUZUKI Y1, HARADA N2, SHIMPO H1, KURIHARA D1, MUTOH R1, OHKUBO C1

1) Dept. of Removable Prosthodontics, Tsurumi University School of Dental Medicine
2) Dental Technician Training Institute, Tsurumi University School of Dental Medicine

Introduction
Infraocclusion is one of the most difficult prosthetic problems because it often leads todenture fracture and the pain of alveolar ridge due to excessive occlusal force andinsufficient denture space. In this case report, a case of partial denture with magnetic
attachments and zirconia framework for a patient with Eichner's classification B4 who
had a infraocclusion due to high occlusal wear, was introduced.

First consultation
Patient: 84 years old, male
Chief complaint: Masticatory disturbance and repeated denture fractures
Past history: Right trigeminal neuralgia
Remaining teeth:

74 2
3

2

57

Eichner classification: B4

Fig.1 Intraoral at first consultation

Fig.2 Panoramic x-ray

6

Table 1. Pocket depth
Pocket (mm) 4 / / 4 / 3 3 3 3 / / / / /dental formula 7 6 5 4 3 2 1 1 2 3 4 5 6 7
dental formula 7 6 5 4 3 2 1 1 2 3 4 5 6 7
Pocket (mm) / / / / 3 3 3 3 3 3 3 3 / 4Materials and Methods
Since infraocclusion was considered as the cause of the disturbance, occlusal verticaldimension was increased by insertion of mandibular treatment denture that covered on
the occlusal surfaces of the remaining teeth (Fig. 3). After obtaining an adequate
occlusal relationship, the definitive denture was fabricated, which was supported by
occlusal rests on the worn occlusal surfaces similar to the treatment denture. The
magnetic attachment (GIGAUSS C, GC) (Fig. 4) and clasps were applied as retainers,
the framework including major connector was milled from zirconia disk based on thescanned STL data of the wax denture (Aadva EϨ, GC) (Fig. 5). The zirconia framework
was tried to fit in patient’s mouth, then the mandibular removable partial denture wasconventionally completed (Fig. 6-8). After about three weeks from the definitive
denture were deliverd, the magnetic assembly was fixed to the zirconia framework.

  Fig. 3 Treatment denture    Fig. 4 Magnetic attachment (GIGAUSS C, GC)




7

D

E
Fig. 5b Repair the undercut of remaining
teeth and space making for magnetic
assembly

Fig. 5a Scanned image ofmandibular working modelF
Fig. 5c Framework design

Fig. 6 Trial fitting of zirconia framework(High permeability zirconia, Aadva EϨ)Fig. 7 Definitive mandibular denture

8Fig. 8 Placement of the definitive denture

Results and Discussion
Compared with the previous denture, the definitive denture improved denture rigidity
and stability. Futhermore, the occlusal contact area and the maximum occlusal force
were increased.(Fig.9) The paitient’s satisfaction and masticatory function were
improved by the placement of removable partial denture with the magnetic
attachments and zirconia framework using CAD/CAM technology.

Previous denture

Definitive denture

Fig. 9 Occlusal examination by dental prescale9

Clinical evaluation of implant overdentures using magnetic㻌
attachment: retrospective study
Takayama H1,2)䠈Suzuki Y1,2)䠈Kurihara D1,2)䠈Maruo R1,2)䠈Shimpo H1,2),Ohkubo C1,2)
1)

Dept. of Removable Prosthodontics䠈Tsurumi University School of Dental Medicine
Center of Oral and Maxillofacial Implantology, Tsurumi University School of Dental Medicine

2)Introduction
Implant overdenture (IOD) is one of the most effectiveness treatment for removable denture
treatment to provide improvement for removable denture. The objective of this retrospective clinicalstudy was to evaluate performance of IOD using magnetic attachment and to identify risk factors forprosthetic complications.

Materials and Methods
This retrospective study evaluated data collected from edentulous and partial edentulous patientstreated April 2003 and November 2018 in Tsurumi University with IOD using magnetic attachment.
Outcome measures were implant and prosthetic survival rates, patient age when IOD delivering,ratio of male and female, location and number of implant.

Results
A total of 14 patients (3 males and 11 females) with 42 implants (30 maxilla and 12 mandibular) and
36 magnetic attachments were included in this study.The mean age of these patients was 65.5 years(in a range from 64 to 80 years) (Fig. 1,2). The patients were treated using a conventional 2-loading
protocol.

Fig.1 Gender ratio

Fig.2 Age Gender10

A total of 42 implants were placed, 30 (71,4%) in the maxilla and 12 (28,6%)in the mandible. The
positions of implant placement were: incisor (14,3%)㸹canine (47,6%)㸹premolar (23,8%) andmolar(14,3%). In mandibular, a greater number of implants were anterior compared to posterior. (Fig.
3). Two different implant systems were used : 30 implants were regular implants and 12 implants
were mini implants(Fig.4). Approximately 2patients (14,3%) were partially edentulous, and12patients (85,7%) were fully edentulous (Figures 5). The most common denture material was resinbase (8 dentures), followed by Co-Cr base (4 dentures) and titanium base (2 dentures) (Fig. 6).

Number of teeth

Number of teeth
Tooth type

Tooth type

MaxillaMandibular
Fig.3 The position of Implant placement

Fig.4 Type of implantFig.5 Missing teeth situation

Fig.6 Denture modalities

One (maxilla incisor) of 42 implants failed because of lack osseointegration, during the 7 years after
placement. The implant have functioned at a rate of 97 % (maxilla91,7% mandible 100%). The
failed implamt case was no occlusal contact in spite of remaining maxillary and mandibular teeth(Eichner classification C1), which is caused by excessive occlusal force to the implant. In prosthetic
complication, attachment loosing (maxillary anterior region and mandibular canine region) wereobserved 3 patients, during the 1 to7 years after denture delivered. (Figs.8and 9 ). However someof attachment looseing and detachment may also be attributed to nomal functions, including patient
insertion and removal of the prostheses. Therefore, it seems to be impotant that controls for thesecomplication risks be made at regular intervals in clinic.

11

Number of troubles
Tooth typeFig.8 Complication

Fig.9 Complication area

Conclusions
In this study, 14 patients (mean age 65.5 years, 3 males and 11 females) with 42 implants and 34
magnetic attachments with a maximum follow-up of 16 years were included. One of 42 implants
were failed and attachment loosing were observed 3 patients, but most of the patients were usedwithout any major complaints.The implant over denture with magnetic attachment were exceedingly
for rehabilitation with a high survival rate.

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Mechanical consideration of implant support in removable partial
denture design applied by a magnetic attachment using
three-dimensional finite element analysis
Kumano H, Kanbara R, Fujinami W, Matukawa R, Ando A, Hata M, Kojima N, Yoshioka F,
Ozawa S, Nakamura Y, Nakamura H, Shoji K and Takebe J.
Department of Removable Prosthodontics, School of Dentistry, Aichi Gakuin University
Abstract
The purpose of this study was to examine the mechanical effects of implant support in removablepartial denture design using three-dimensional finite element analysis. The analysis model was apartial edentulous mandibular where #35, 36, 45, 46 and 47 were missing. For design of the basicmodel, the RPI clasps were designed on #34 and #44 as retainer, and a magnetic attachment wasapplied on #37 as overdenture abutment. The implant support models were created in which two
types of implants with different lengths (6.5 mm and 10.0 mm) were placed in cantilever missing on
the right side of the mandible of the basic model. Stress analysis of these analysis models was
conducted. In the implant support models, there was no significant difference in the analysis results
depending on the length of the implant. Additional support by the implant demonstrated the stress
reducing of the abutment teeth even by the short implant. These results suggest implant supported
removable partial denture would expand its indication on designing removable partial denture.

Introduction
In the design of removable partial dentures in which tooth support and tissue support with different
amount of tissue displacements are complicated, it is very difficult to set appropriate mechanicaldistribution especially for cantilever missing.
In such a situation, the application of the magnetic attachment to the posterior molar can change themissing form from the cantilever missing to an intermediary missing by providing the tissue support
at the posterior position. In addition, it is clinically very useful to acquire the retentive force of thedenture by the attractive force of the magnetic attachment.
In recent years, as a method of prosthetic treatment from the crown bridge to the removable denture,
although implant treatment has been established, as another method, as well as the magnetic
attachment applied to the posterior molar, There is also report on the use of implant support in the at
the posterior position to stabilize removable partial denture.
However, there are still many questions about the mechanical effects of implant support in thedesign of removable partial denture.

Objective
The purpose of this study was to examine the mechanical effect of implant support in the design ofremovable partial denture applied by a magnetic attachment using three-dimensional finite element
analysis.

Material and Methods
1. Analysis model
The mandibular model used in this study is shown in Fig.1. For model construction, a mandibular
plaster model and a skull model (P10 - SB.1) manufactured by Nissin Co., Ltd. were used (Fig. 2).
Initially, this mandibular plaster model was scanned using a model and impression scanner (7 series,

19

Dental Wings, Montreal, Canada) to makemodel shape data in STL format. Next, askull model was CT photographed and theobtained CT data was prepared in STL
format with mandibular bone data andtooth root shape data using
three-dimensional construction soft
Fig.1 : The mandibular
Fig.2 : Mandibular plastermodel used in this study
model and a skull model(Mimics version l1.0㸪Materialise㸪Leuven㸪Belgium). We imported these data into computer
aided engineering㸦CAE㸧pre㸭post processing software(Patran 2013 windows 64bit, MSC software, Los Angeles,
USA) and constructed a model. The thickness of theresidual ridge mucosa and periodontal ligament were set
with reference to the literature values and the morphologyof the mandible was simple form. 1
Fig.3 : The design of the removable partial denture
The design of the removable partial
denture is shown in Fig.3. The
magnetic attachment was applied on#37 as overdenture abutment and the
RPI clasp was applied on #34 and #44
as the direct retainer. The magnetic
attachment applied in this research
was GIGAUSS D1000 and accurately
reproduced its high diameter andwidth for model construction.
The analysis model created by the above
method was used as the basic model in this study.

Fig.4 : Analysis items

2. Analysis Items
Table1 : Mechanical property values
Analysis items are shown in
Fig.4. The implant supportmodels were created in which two
types of implants with different
lengths (6.5 mm and 10.0 mm)
were placed in cantilever missing
on the right side of the mandible ofthe basic model. The implant of theimplant support model was
equipped with a healing abutment (height 4.0 mm) and set as a support
area under the denture base.
The mechanical property values of the analysis model are shown in
Table 1. About the periodontal ligament and the residual ridge mucosa,these nonlinear viscoelastic properties were introduced by material
constant conversion program㸦Table 2㸧.
3. Analysis Conditions
The load conditions are shown in Fig.5. The
loading site was a total of 4 places on the denture
occlusal surface and the loading direction wasperpendicular to the occlusal plane. Based on theliterature value, the load amount was set to 200 N
in total2. The inferior border of the mandible was defined as aconstraint condition in the x, y, and z directions. In the contact

Table2 : Material constantconversion program

Fig.5 : Load conditions

20

condition, the contacting relationship with the tooth and the mucosa in contact with the denture wasadded by Coulomb friction and the coefficient of defined Coulomb friction was set at μ = 0.090 for
this study. 3
The evaluation of the analysis results was based on the Von Mises stress and the displacement of
the denture.

Analysis Results
1. Stress distribution in the alveolar boneFig. 6 shows a stress
distribution in the alveolar bone
in each abutment tooth. In the#37 of the alveolar cavity whichapplied a magnetic attachment,
stress relaxation was confirmedin the implant 10.0 model, theimplant 6.5 model as comparedwith a basic model. Next, in the#34 of the alveolar cavity, no
significant difference wasconfirmed in the alveolar cavity
in any of the models. However, inthe distal alveolar cavity, stressrelaxation was confirmed in theimplant 10.0 model and theimplant 6.5 model compared withthe basic model.
2. Stress distribution in
Fig.6 : Stress distribution in the alveolar bone
the residual mucous
membraneFig. 7 shows the stress
distribution in the residual mucous
membrane. In the residual mucous
membrane of the right side,
significant stress relaxation wasobserved in the implant 10.0 modeland the implant 6.5 model comparedwith the basic model, confirming thatFig.7 : Stress distribution in the residual mucous membrane
the mucosa supporting area of denture
was decreased. Next, comparing the implant 10.0 model with the implant 6.5 model, no significant
difference was observed in stress distribution in the residual mucous membrane.
3. Displacement of denturebaseFig. 8 shows the amount of
displacement of the denture base. In
the part corresponding to the # 45,
46 and 47, a decrease in the amountof displacement was observed in theimplant 10.0 model and implant 6.5
model compared with the basic
Fig.8 : A mount of displacement of the denture base

21model. The basic model showed a tendency for the displacement amount to increase toward the
distal side, and the implant 10.0 model and the implant 6.5 model showed a tendency for the
displacement amount to increase toward the mesial side. In the part corresponding to the # 35, 36
and 37, the difference in the amount of displacement was not observed in all models, and the amountof displacement tended to increase toward the mesial side.

Discussion and Conclusion
From the results of this study, as a mechanical effect of implant support in the design of removablepartial denture,
1: Stress relaxation was observed in the tissue around the abutment tooth, including the magnetic
attachment.
2: In the burden style of denture, it was confirmed that the tissue borne area was reduced and thedisplacement of the denture base was suppressed.
3: In the implant 10.0 model and the implant 6.5 models, significant differences were notobserved in both stress distribution and denture displacement in the alveolar bone.
Therefore, these results suggest implant supported removable partial denture would expand its
indication on designing removable partial denture.

References
1.
M. Kishi : Experimental studies on the relation between area and displacement of loading
surfaces in connection with displaceability in the mucosa of edentulous alveolar ridge underpressure, Shikwa Gakuho, 72, 17-45,1972.
2.
M. Manda, C. Galanis, V. Georgiopoulos, C. Provatidis, P. Koidis : Effect of severely
reduced bone support on the stress field developed within the connectors of three types ofcross-arch fixed partial dentures, J Prosthet Dent, 101, 54-65,2009.
3.
Y. Sato, Y. Abe, Y. Yuasa, Y. Akagawa : Effect of friction coefficient on Akers clasp
retention, J Prosthet Dent,78, 22-7,1997.

22
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