１．Comparison of Attractive Force for Cast-Bonding and Direct-Bonding Technique
on Dental Magnetic Attachments
Fujio Tsuchida, Yuko Suminaga, Norio Takishin,Toshio Hosoi,
Department of Removable Prosthodontics, Tsurumi University School of Dental Medicine
ABSTRACT
Purpose: In order to obtain maximum attractive force with magnetic attachments, plane accuracy of the keeper surface is important. The purpose of this study was to evaluate the difference in the method of manufacturing a keeper of the magnetic attachment affects an attractive force.
Materials and Methods: Magnetic attachment was performed using a Hyper Slim 3513 (NEOMAX MATERIALS Co., Ltd.). Specimens were made for cast-bonding （n=5） and direct-bonding (n=5) technique. The attractive force was measured using the digital force gauge (NIDEC-SHIMPO Co., FGC-1) in this study.
Results: The attractive force for two groups was statistically analyzed using t-test (p<0.05). There was a significant difference between cast-bonding and direct-bonding technique.
Conclusion: As a result of measuring the attractive force of magnetic attachment made by two techniques, magnetic attachment of direct-bonding technique showed the attractive force significantly higher than that of cast-bonding technique. As for the attractive force of magnetic attachment, it was suggested that the flatness and the smoothness of the keeper surface have influenced.
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２．Comparison of retentive force of different overdenture stud attachments in
various dislodgement patterns. In vitro study Part 2 Changes after Fatigue Test
Hiroshi Mizutani 1, Darline Destine1, Amarsanaa Bazar1, Kazuo,Nakamura2, Shin Ishikawa1, Hidetaka Sasaki1,
Shinya Matsuzaki1, Chihiro Tsuda1, Yasutomo Ogasawara1, Hirotaka Kazama1, Tatsu Matsumoto1, Yoshimasa
Igarashi1
1 Section of Removable Prosthodontics raduate School, Tokyo Medical and Dental University
2 Organized Center of Clinical Medicine Intrnational University of Health and Welfare
ABSTRACT
Objectives: To evaluate quantitative fatigue characteristics of overdenture attachments.
Methods: Seven commercially available attachments were tested: Era Overdenture orange and white Locator Root pink, white and blue, O-P anchor #4 and Magfit DX600W. Five specimens of each type of attachment were used. For Magfit DX600W, consecutive loadings were 0-2000 cycles and for the others 15000 insertion-removal cycles performed in 37C demineralized water. Maximum retentive force (N) was measured initially and after each 100 cycles.
Results:
Maximum Retentive Force
As for Era Orange and Era White sudden decrease follow by a constant curve was characteristic. Locator Pink, Locator White and Locator Blue increased after initial decrease. Locator Pink, Locator White and Locator Blue attachments had relatively wide variability among the different specimens.
Average Retentive Force
Era overdenture decreased sharply and continued to the same level during the 15000 cycles. The Locator Root overdenture decreased also at the beginning but rise slowly during the insertion-removal cycles.. However, O-P Anchor after a slight increasing persist on the same level. Regarding Magfit, it keeps the same level. After 2000 insertion-removal cycles for Magfit and 15000 for the other attachments, the retention was constant only for O-P anchor and Magfit.
Conclusion:
1) Decrease in retention of overdenture attachments is found for most of the specimens after fatigue test.
2) Magnetic attachments showed constant retentive force throughout the cycle.
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３．Clinical Application of Magnetic Attachment for Retention and Connection of
Maxillofacial Prosthesis
Eri Makihara 1, Shin-ichi Masumi 1, Masahiro Arita1, Tadafumi Kurogi2, Kohichi Sato3, Tetsu Takahashi 4,
Jinichi Fukuda3
1 Division of Occlusion & Maxillofacial Reconstruction, Kyushu Dental College.
2 Division of Removable Prosthodontics and Management of Oral Function, Nagasaki University.
3 Division of Maxillofacial Diagnostic and Surgical Science, Kyushu Dental College.
4 Division of Oral and Maxillofacial Reconstructive Surgery, Kyushu Dental College.
ABSTRACT
This study describes the fabrication method for a maxillofacial prosthesis by applying dental magnetic attachments for retention and connection. A 73 - year-old male patient with defects in the region of the right upper palate and right cheek after resection of squamous cell carcinoma had worn a removable partial prostheses and epithese. But he had been complaining of mastication, articulation, and esthetic problems. We reconstructed his new prosthesis. The evaluation of mastication and articulation was done before and after wearing the new prosthesis and his complaining improved.
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４．Effect of extremely low frequency magnetic field on proliferation of MC3T3-E1
cells
Imaizumi Y, Ozawa S, Tanaka Y
Department of Removable Prosthodontics, School of Dentistry, Aichi-Gakuin University
ABSTRACT
A purpose of this study was to elucidate a mechanism of promotional effect of extremely low frequency magnetic field (ELMF) on the healing of bone injury. At first we accessed an intensity of the magnetic field on the proliferation of mouse osteoblastic cell line (MC3T3-E1 cells). Culture was exposed by the time varying electro-magnetic power unit (Toei Co.) at 0.5 Hz at various magnetic intensity between 100mT and 1T. Cell proliferation was measured on the WST-8 method after 3 days of culture. As a result, an hour exposure of ELMF at 100mT inhibited its proliferation, however, 24 hours consecutive exposure of 1T significantly promoted cell proliferation of MC3T3-E1 cells. These results suggested that ELMF affects cell proliferation dependent on the duration of the exposure and magnetic intensity.
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５． Evaluation of an electromagnetic jaw tracking device using a pair oftriaxial coils
Shuji Shigemoto, Eiichi Bando, Teruaki Ishikawa, Mariko Kitamura, Takeshi Yamamoto, Naoto Noguchi,
Motoharu Kori, Takaho Shigemoto, Masanori Nakano
Department of Fixed Prosthodontics, School of Dentistry, The University of Tokushima
ABSTRACT
A lot of useful diagnostic information of stomatognathic function is included in jaw movement data. The purpose of this study was to evaluate the data acquisition and data analysis of a new electromagnetic jaw tracking device with high usability and high accuracy based on the jaw tracking device utilizing a pair of triaxial coils (Kawaguchi 2002). Forty-five asymptomatic (23 males and 22 females) and 35 symptomatic (17 males and 18 females, with temporomandibular disorders) adult volunteers were participated in this study. The quantitative analyses of jaw movements were performed using the 36 jaw movement parameters (Ueda 1993). The means and standard deviations of jaw movement parameters considered the male and female reference values were computed from asymptomatic volunteers respectively. Thirty-three subjects who have temporomandibular joint clicking were found in symptomatic volunteers. Their jaw movement parameters were also calculated and compared to reference values. Additionally one dentist evaluated all subjects' jaw movement on width, smoothness, symmetry and reproducibility of incisal trajectories qualitatively.
The result of this study shows that the new device provides chairside high accuracy measurement of jaw movement and the quantitative and qualitative evaluations of jaw movement may be one of effective methods to diagnose temporomandibular disorders.
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６．Comparison of Load Transmission by Removable Partial Dentures with Magnetic
Attachments.
Y.Nakmura1, H. Nakamura1, K.T.Ochiai2, Y. Tanaka1, A.A. Caputo.2
Schools of Dentisry, 1Aichi-Gakuin University, Japan and 2UCLA
ABSTRACT
Objectives: Advances in technology have resulted in improved magnets for dental applications. These improvements have increased the potential for the use of magnets as retaining elements for prostheses. The purpose of this study was to photoelastically compare the forces exerted on the supporting structures by bilateral distal extension removable partial denture designs employing magnetic attachments.
Methods: A composite photoelastic model was made of a mandible bilaterally edentulous distal to the second premolars. Individual simulant materials were used for tooth structure, periodontal ligament, and alveolar bone. The teeth, roots, and tissue contours of the model were of average size and shape. Three partial dentures incorporating magnetic attachments (MAGFIT, Aichi Steel Corp.; Japan) were fabricated.with retaining keepers in different positions: a) radicular overdenture coping keeper, b) telescopic crown with internal retaining keeper, c) full crown with distal extracoronal keeper. One direct retainer design (RPI) also was made for comparison. Simulated occlusal loads were applied to the dentures The stresses which developed in the supporting structures were photographed in the field of a circular polariscope.
Results:. For all load conditions, the RPI extracoronal clasp design demonstrated the most uniform stresses about the supporting abutment tooth. Of the magnetic designs, the overdenture radicular-type coping keeper design generated the most uniform stresses, and was similar to the RPI. The telescopic crown with internal retaining keeper and the full crown with distal extracoronal keeper produced higher stress with a tendency towards distal rotation of the abutment tooth.
Conclusions: While the RPI extracoronal clasp design tended to transfer applied loads most equitably, the characteristics of the radicular overdenture coping keeper design were similar. Use of this magnetic attachment may be considered when esthetic considerations are paramount.
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７．The extracoronal magnetic attachment using ready-made pattern
Tetsuo Ohyama1,2,Tomohiko Ishigami1,2, Setsuko Sakaguchi 3, Eiichi Nagai1,2, Kenji Ohtani1,2, Toshiki Fujimoto1,
Yuusuke Katakura1, Masaaki Takamura1,Aiko Majima1
1 Department of Removable Partial Denture Prosthodontics, Nihon University School of Dentistry
2 Division of Oral and Craniomaxillofacial Research, Dental Research Center, Nihon University School of Dentistry
3 Dental Technicial Training School, Nihon University School of Dentistry
ABSTRACT
As applications of the magnetic attachment, it is classified with into the stad attachment and the MagnoTelescope Crown. The both attachment when it is applied to the nonbital tooth is many. However, it is important because also adaptation to the bital tooth expands the applied range to the magnetic prosthes. The case is ready-made pattern for extracoronal attachment due to the magnetic attachment [GIGAUS] used. This report was examined for especially labo work. The extracoronal magnetic attachment due to ready-made pattern is simple and useful.
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