16. An Application of Magnetic Attachment to Cast Clasp
- Development of Magnetic Rest Clasp -

Toshiaki Hasuike, Toshiyuki Kusano, Fumiko Okutsu, Takaaki Matsukawa, Mineyo Sone, Shuji Ohkawa

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

Introduction

The increased emphasis on physical appearance in contemporary society has increased the demand for esthetic dental treatment.

The metallic color of the buccal clasps on premolars or canines is one of the common causes of patient rejection. The appearance would be vastly improved if metal buccal clasps were eliminated. However, the retentive function of clasps eliminated buccal arms is extremely poor. We developed a new retainer of no buccal clasp arm with the magnetic attachment in the occlusal rest of clasps (Magnetic Rest Clasp).

The purpose of this study is to introduce the fabrication of a new retainer "Magnetic Rest Clasp" for lower premolars with a plastic jaw model having artificial teeth.

Fig.1 Keeper and its housing pattern

Fig.2 Magnetic assembly and its housing pattern

GIGAUSS C400 (GC) was used in this report.

Fig.3 Working model (lingual view of the abutments)

Fig.4 Working model (occlusal view of the abutments)

The abutments have partially concave forms for the magnetic attachment.

Fig.5 Wax pattern of connected full cast crown

The wax pattern has guide plane on the lingual and distal sides.

Fig.6 Space adjustment of the wax pattern for keeper and magnetic assembly with surveyor

Minimum 0.3mm thickness of wax between keeper and abutment is required for proper casting.

Fig.7 Wax pattern with keeper housing pattern

Fig.8 Connected full cast crown without keeper on the working model (lingual view)

Fig.9 Connected full cast crown without keeper on the working model (occlusal view)

The connected full cast crown is cast with 12% gold and silver palladium alloy (CASTWELL M.C., GC)

Fig.10 Connected full cast crown with keeper on the working model

The keeper is fixed with a cementing material (Super-Bond C&B, SUN MEDICAL).

Fig.11 Resin pattern of Magnetic Rest Clasp and minor connector, incorporating magnetic assembly housing pattern (lingual view)

This pattern has no buccal clasp arm.

Fig.12 Finished Magnetic Rest Clasp (lingual view)

Fig.13 Inner surface of Magnetic Rest Clasp

Magnetic assembly is fixed with a cementing material (Super-Bond C&B, SUN MEDICAL)..

Fig.14a lingual view Fig.14b occlusal view Fig.14c buccal view

Fig.14 The Magnetic Rest Clasp seated in the connected full cast crown on the working model

Conclusions

In this study, we introduced the fabrication of a new retainer "Magnetic Rest Clasp" for lower premolars with a plastic jaw model having artificial teeth.

For the future we will try to apply the Magnetic Rest Clasp to a porcelain fused to metal crown for patients.

Discussion Board