A Case Report of the Removable Partial Denture with the MagneticAttachment Applied to the Pontic of Anterior Bridge

Mineyo SONE, Yumiko TOYOTA, Risa NEGORO,Shigeru YORICHIKA, Kazuhiko OKAMOTO and Shuji OHKAWA

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

Abstract : The metallic color of the buccal clasps on cuspids and premolars in the removable partial denture is a common cause

of patient complaint, because it is not aesthetic. If buccal clasps were removed, the aesthetic appearance would be improved. How-

ever, the lack of the buccal clasp arm would be decreased the retentive function in these removable partial denture. So we devel-

oped a new retainer with no buccal clasp arm with the magnetic attachment in the occlusal rest of the clasps (Magnetic Rest

Clasp). In this case report, we report the fabrication of a removable partial denture using a modified Magnetic Rest Clasp in a can-

tilever bridge pontic. The patient, a 61-year-old female, complained of aesthetic dissatisfaction and masticatory dysfunction. A pa-

tient received a maxillary removable partial denture several years ago, but she was dissatisfied with the visible metal clasp on the

anterior teeth. As a definitive prosthesis, a maxillary removable partial denture was fabricated with a Magnetic Rest Clasp that ap-

plied to porcelain fused to a metal cantilever bridge (#11, 21 and the pontic at #22). The patient was satisfied with the aesthetic re-

sult of definitive prosthesis and the prosthetic retentive function without a clasp of the anterior teeth. In the 1 year since final pros-

thetic treatment, no complication with this fitted denture has occurred.

Key words : removable partial denture, magnetic attachment, Magnetic Rest Clasp

前歯部延長ブリッジのポンティック部に磁性アタッチメントを使用した可撤性局部床義歯の 1症例

曽根 峰世§ 豊田有美子 根来 理沙頼近 繁 岡本 和彦 大川 周治明海大学歯学部機能保存回復学講座歯科補綴学分野

要旨：可撤性局部床義歯の犬歯および小臼歯部における頬側クラスプの金属色は，審美的ではないので，患者が不満に思う共通した原因の 1つになっている．もし頬側クラスプを取り除くことができれば，審美的な外観は改善されるだろう．しかし，部分床義歯における頬側クラスプアームの欠如は維持力を低下させる事になる．そこで，我々はクラスプの咬合面レスト部に磁性アタッチメントを応用した，頬側クラスプアームの無い新しい支台装置「Magnetic Rest Clasp」を開発した．本報告では，延長ブリッジのポンティック部に「Magnetic Rest Clasp」の形態を一部修正して応用した上顎可撤性局部床義歯の製作について報告する．患者は 61歳の女性で，審美障害および咀嚼障害を主訴に来院した．数年前に上顎可撤性局部床義歯を装着したが，前歯部の目立つ金属クラスプに不満を有していた．最終補綴装置として，前歯部メタルボンドブリッジの延長ポンティック部に Magnetic Rest Clasp を応用した上顎可撤性局部床義歯を製作した．患者は審美的な結果と，前歯部にクラスプを設けることなく得られた可撤性局部床義歯の維持力に満足した．現在，最終補綴終了後 1年が経過したが，装着した義歯に問題は生じていない．

索引用語：可撤性局部床義歯，磁性アタッチメント，Magnetic Rest Clasp

明海歯学（J Meikai Dent Med）41（1）, 61−65, 2012 61

Introduction

The demand for aesthetic dental treatment has beenincreasing in contemporary society. The metallic colorof the buccal clasps on cuspids and premolars in theremovable partial denture is a common cause of pa-tient complaint, because it is not aesthetic. If buccalclasps were removed, the appearance would be im-proved. However, the lack of the buccal clasp armwould be decreased the retentive function in these re-movable partial denture. We developed a new retainerwith no buccal clasp arm. It had the magnetic attach-ment in the occlusal rest of the clasps (Magnetic RestClasp1−3)). In this case report, we describe the fabrica-tion of a removable partial denture using a modifiedMagnetic Rest Clasp.

Clinical History

The patient, a 61-year-old female, complained ofaesthetic dissatisfaction and masticatory dysfunction.

The patient had a partially edentulous maxilla(Kennedy class Ⅱ). She refused to have a maxillaryremovable partial denture because the patient was dis-satisfied with the visible metal clasp on the anteriorteeth.

Porcelain fused to metal crowns (#11, 21 and 22),resin-faced crowns (#12, 13, 14 and 15) and metal

crowns (#16 and 17) were placed (Fig 1). However,all prostheses were failing restorations with the mar-ginal discrepancy, and tooth #22 was damaged by car-ies. In addition, mobile teeth and poor periodontal tis-sue health were evident (Fig 2).

A radiographic examination was showed endodonticproblems of apical radiolucencies and poor endodontic

─────────────────────────────§Correspondence : Mineyo Sone, Division of Prosthodontics, Depart-

ment of Restorative and Biomaterials Sciences, Meikai UniversitySchool of Dentistry, 1-1 Keyaki-dai, Sakado, Saitama 350-0283, Ja-pan

Fig 1 Study model at the initial visit

Fig 2 Periodontal chart at the initial visit

Fig 3 Dental radiographs at the initial visit

62 SONE M, TOYOTA Y, NEGORO R et al J Meikai Dent Med 41, 2012

fillings (Fig 3).

Treatment Procedure

At first, the prosthesis with the marginal discrep-ancy was removed, and temporary restorations were

placed. After the initial preparation, the treatment den-ture was delivered, and the patient obtained the oc-clusal relationship. The patient then wanted to cut out

Fig 5 Top and bottom view of a new fabricated maxillary removable partial denture

Fig 6 Magnetic Rest Clasp and porcelain fused to metal cantilever bridge with a keeper

Fig 4 Maxillomandibular registration for a maxillary removablepartial denture

Fig 7 Magnetic attachmenta : Keeper ; b : Keeper tray ;c : Magnetic assembly ; d : Housing pattern(GIGAUSS C 400, GC, Japan)

A Case of RPD with a Magnetic Attachment 63

the metal clasp on the anterior teeth to correct the aes-thetic problems. As a definitive prosthesis, the metalcrown (#16 and 17), porcelain fused to metal crown(#12, 13, 14 and 15), porcelain fused to a metal canti-lever bridge (#11, 21 and the pontic at #22) and metalcoping under the pontic at #22 were sat using adhe-sive resin (Super-Bond C&BⓇ, SUN MEDICAL, Ja-pan). A maxillary removable partial denture with theMagnetic Rest Clasp was fabricated in the conven-tional impression technique and maxillomandibularregistration (Figs 4 and 5). A keeper of a magnetic at-tachment applied to the pontic (#22) of the porcelainfused to metal cantilever bridge (Fig 6). The magneticattachment used in this case report was GIGAUSS C400Ⓡ (GC, Japan) (Fig 7). A keeper of a magnetic at-tachment and a magnetic assembly were cementedwith adhesive resin (Super-Bond C&BⓇ, SUN MEDI-CAL, Japan). An intraoral view with a final prosthesisis presented in Figs 8 and 9.

Discussion

In this case report, the patient accepted and toler-ated the definitive prosthesis with a Magnetic RestClasp. Female patient frequently objected to solutionsrequiring removable partial dentures for aesthetic rea-sons. Magnetic attachments have been recently used asretentive structures in removable partial dentures4−10).Typical magnetic applications include studs11), extra-coronal attachments12) and telescopic crowns13). Withsuch applications, it has advantage of an aesthetic, be-cause there are no metal clasps in the removable par-tial denture using the magnetic applications. Howeverthe magnetic assembly which is remained in the oralact as functionally-deficient structure that has an aes-thetic problems in removing the denture. MagneticRest Clasp is more aesthetic than them, because Mag-netic Rest Clasp is modified intercoronal attachmentand have satisfactory appearance of anatomical crown.Thus patient’s complaints of aesthetic dissatisfactionare improved.

A magnetic attachment provides the supports andthe retention elements, but it has no bracing elementfor horizontal force control. In this case report, theabutment crown of the Magnetic Rest Clasp (the pon-tic at #22) has both guide planes and channels that actas a bracing element. These structures make it possi-ble to fix a magnetic assembly at the normal positionfor a keeper. A magnetic assembly and a keeper worktogether to serve as a rigid retainer.

The cantilever bridge that has the extension of dis-tal side could be exposed to overload on the abutment

Fig 9 Borderline between pontic and denture

Fig 8 Intraoral view with definitive prosthesis

64 SONE M, TOYOTA Y, NEGORO R et al J Meikai Dent Med 41, 2012

teeth. It is considered that the excessive occlusalforces are could be due to drop off the cantileverbridges. Therefore, the forces have to be taken controlduring using of them. In this case report, the abutmentteeth (#11 and 21) are interconnected and metal cop-ing as support element for vertical force is attachedunder the pontic of a cantilever bridge. As a result, acantilever bridge has dynamic stability.

The magnetic attachment used in this case report,GIGAUSS C 400Ⓡ, is very compact device (3.5×2.7×1.6 mm). In addition, the magnetic retentive force issufficient (400 gf) and nearly permanent. The pontic at#22 required to set partially concave space on palatalside for the magnetic attachment inserting, but thatspace is very small and narrow. So we chose it in thiscase report.

It is difficult to maintain the ideal combination ofaesthetics and functionality because the design of a fi-nal prosthesis is complex. So continuous follow-up isnecessary with bite raising and relining of the denturebase to prevent any reduction of the occlusal verticaldimension. In addition, periodontal management andforce control of the remaining dentition are required.

Conclusion

The results suggest that the Magnetic Rest Clasp isaesthetic and has satisfactory retention for porcelainfused to metal crowns in the removable partial den-ture. In the 1 year since final prosthetic treatment, nocomplication with this fitted denture has occurred. Inclinical use, the retentive forces occurring in the re-movable partial denture functions to resist the dis-placement of the denture. It is important that weevaluate the resulting forces of a certain level or de-structive effect on the structures. Therefore, the reten-tive force of the Magnetic Rest Clasp and the peri-odontal structure around the abutment teeth should beevaluated at the maintenance program to ensure theadequate retention for the magnetic attachment using

this removable partial denture.

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(Received October 31, 2011 ; Accepted November 30, 2011)

A Case of RPD with a Magnetic Attachment 65