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

February 26 to March 16, 2021

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 a decreased 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

Division of Removable Prosthodontics, Department of Restorative and Biomaterials Sciences, Meikai University School of Dentistry


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 removable partial 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.


#2. A case report of removable partial denture applied magnetic attachment and zirconia framework for a patient with a decreased occlusal vertical dimension


1)Dept. of Removable Prosthodontics, Tsurumi University School of Dental Medicine

2)Dental Technician Training Institute, Tsurumi University School of Dental Medicine



Infraocclusion is one of the most difficult prosthetic rehabilitation because it often leads to the denture fracture and the pain of alveolar ridge due to excessive occlusal force and insufficient denture space. In this presentation, we report a case of removable partial denture with magnetic attachments and zirconia framework for a patient with Eichner's classification B4 who had a infraocclusion due to highly wear of occlusal surface.


The patient was 84-years-old man with missing unilateral premolars and molars in the mandibular jaw. His chief complaints were masticatory disturbance and repeated denture fractures. Since the cause of the disturbance was considered infraocclusion, occlusal vertical dimension was increased by insertion of treatment denture that covered on the occlusal surfaces of the remaining teeth. After obtaining an adequate occlusal relationship using an treatment dentures, the definitive denture was fablicated, which was supported by occlusal rests on the worn occlusal surfaces of the remaining teeth. The magnetic attachment and clasp was applied as retainers, the major connector was used made of zirconia framework manufactured by milling.

【Results, Discussion】

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.


#3. Clinical evaluation of implant overdentures using magnetic attachment: retrospective study

Takayama H1,2),Suzuki Y1,2),Kurihara D1,2),Maruo R1,2),Shimpo H1,2), Ohkubo C1,2)

1) Dept. of Removable Prosthodontics,Tsurumi University School of Dental Medicine

2) Center of Oral and Maxillofacial Implantology, Tsurumi University School of Dental Medicine



Implant overdenture (IOD) is one of the most effectiveness treatment to improve the stability of the conventional removable denture by implant support. The objective of this retrospective clinical study was to evaluate the performance of IOD using magnetic attachment and to identify risk factors for prosthetic complications.

【Materials and Methods】

This retrospective study evaluated IODs using magnetic attachments which delivered to fully and partial edentulous patients between April 2003 and November 2018 in Tsurumi University Dental Hospital. Outcome measures were survival rates of implants and prosthetic devices, patient age when IOD placed, ratio of male and female, location and numbers of magnetic attachments, and Kennedy classification, etc.

【Results, Discussion】

A total of 14 patients (mean age: 65.5 years, 3 males and 11 females) with 42 implants and 34 magnetic attachments were included in this study. As results, 1 implant (2.3 %) was lost and 3 loosening of the abutment screw were observed. IODs can be used by most of the patient without any major complications.

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. Takahashi1, G. Togawa1, M. Kanyi2, H. Yamaguchi1,3 and Y. Takada1

1Division of Dental Biomaterials, Tohoku University Graduate School of Dentistry

2Moi Teaching and Referral Hospital, KENYA

3Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry


ISO 13017:2020 has specified a device for measuring the retentive force of dental magnetic attachments accurately. The recommended crosshead speed of measuring the retentive forces using this device has not been investigated yet. In this study, the retentive force measurements of two different types of magnets (Nd-Fe-B, Sm-Co) and one magnetic attachment (GIGAUSS D600) were done at crosshead speeds of 0.5 – 500 mm/min. From the obtained data the impact of crosshead speed on the measured values of retentive force was investigated.

There was no significant difference in the measured values at crosshead speed of 0.5 – 50 mm/min for all magnets and attachment. However, the measured values at 100 mm/min or more were significantly higher than the reference value at 0.5 mm/min. By using the retentive force measuring device specified in ISO 13017:2020, it is possible to measure retentive forces accurately at crosshead speed of 35 mm/min. Crosshead speeds above 50 mm/min yield measured values higher than the true retentive force as a result of extra force necessary to accelerate the movable part of device to the highly set crosshead speed.


#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.

Department of Removable Prosthodontics, School of Dentistry, Aichi-Gakuin University


The purpose of this study was to examine the mechanical effects of implant support in removable partial denture design using three-dimensional finite element analysis. The analysis model was a partial edentulous mandibular where #35, 36, 45, 46 and 47 were missing. For design of the basic model, the RPI clasps were designed on #34 and #44 as retainer, and a magnetic attachment was applied 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.