Morphological change in the Magnetic Attachment Surface by Repeated Loads

Shoji K., Masuda T., Nakamura Y., Ando A., Kumano H., Miyata T., Shigemori T.,
Nakamura H., Tanaka Y.

The First Department of Prosthodontics, School of Dentistry, Aichi-Gakuin University

Introduction

In recent years, dentures with magnetic attachments came to be widely used clinically due to availability and numerous applications. Clinical use has shown that durability and wear play a factor in long term maintenance and use of these attachments.

It has been noted that transformational wear and abrasion frequently may develop at the joint area of a magnetic assembly. The magnetic attachment keeper appears to bear the main masticatory force components in the oral cavity over a relatively long duration. Therefore, potential functional damage of magnetic attachment and any possible decline in the attractive force are concerned.

OBJECTIVE

The present study focused on a keeper of a magnetic attachment. The purpose of the present study was to examine the influence of repeated loads applied in the vertical direction and the effect upon surface change and the keeper performance.

MATERIALS AND METHODS

GIGAUSS C 600 and D 600 ( GC ) were used as test samples. ( Fig1. )

As a pre treatment, 10 kgf loads were applied to each sample 100,000 times in 0.8 second cycles. ( reference to a chewing cycle ) ( Fig2. )

Surface observation ( Fig3. )

( using an actual situation microscope of 1.5 magnifications. )

Distortion measurement ( Fig4. )

1. shape

( using 3 Dimensional Digitizer ( MITUTOYO CYCLONE ) )

2.distortion quantity measurement

( using Power Shape (3 Dimensional CAD System ) )

Attractive force measurement ( Fig5. )

( using EZ-TEST ( SHIMAZU ) )

RESULTS

Surface observation

Distortion measurement

After loaded, GIGAUSS C 600, D 600 showed the edge distortion of 10 ∼ 50_and the surface distortion of 10_.( Fig8. Fig9. )

Attractive force measurement

Both GIGAUSS C 600, D 600 showed minor decline in attractive force, but no significant difference was observed.

DISCUSSION

It was confirmed that attractive force remains relatively unchanged, as far as the contact surface of a magnetic attachment is kept well.

REFERENCES

1. Jackson,T.R.: The applicaiton of rare earth magnetic retention toosseointegrated implants. Int. J. Oral & Maxill. Imp., 1: 81-92, 1986.

2. Tanaka, Y.: Dental Magnetic Attachment, Q&A, Ishiyaku Publishers, Inc. (Tokyo), 1995.

3. Mizutani, H., Ishihata, N. and Nakamura, K.: Removable partial denture used the magnetic attachment, Quintessence Publishing Co., Ltd. (Tokyo), 1994.

Discussion Board