Attractive Force of the Magnetic Attachment performed in combinations of MAGFIT EX Keeper and GIGAUSS Magnetic Assembly

Ando A., Nakamura Y., Masuda T., Kumano H., Nakamura H., Miyata T., Terao Y., Tanaka Y.

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

Introduction

Magnetic attachments in dentistry are retaining devices that are utilized to assist in the retention and stabilization of removable dentures in the oral cavity. The degree of retaining power of the magnets utilized determines clinical usage. Magnetic attachments have been widely used effectively with retained and existing dentitions. Magnetic attachments were developed in 1992, and have been well used during the last 14 years. Magnetic attachments have continued in development with new product applications. Variations of special form application and retentive force are now available by different manufacturers. Magnetic attachments are continuing in development as additional products become available to provide multiple applications and newer uses.

OBJECTIVE

Under clinical use, a magnetic assembly is exposed to a severe environment changes which include the oral cavity temperature and the presence of saliva. These clinical conditions under function may result in the loss of a magnetic assembly and denture breakage may ensue. In such cases, it is desirable to repair a fractured assembly using a similar magnetic assembly with a keeper. However, due to the rapid progress of magnetic attachment, the availability of an identical attachment of a compatible or identical design may be difficult to acquire and obtain.

MATERIALS AND METHODS

In the present study, we measured an attractive force under the combinations of the MAGFIT EX 600 (Aichi Steel) keeper and GIGAUSS (GC) magnetic assemblies of each kind; GIGAUSS D series and GIGAUSS C series.

For the attractive force measurement, we used die and JIG devised by us and measured with EZ test ( SHIMADZU ). (Fig1)

The schematic view

Fig. 2 shows the schematic view which illustrates the external form width of MAGFIT EX 600 keeper. The external form of MAGFIT EX 600 keeper is a rectangle with round corners.

The frame design of GIGAUSU D series magnetic assembly is a circle, and that of GIGAUSU C series is a circle with the edges cut off two parallel sides.(Fig3) In comparison with GIGAUSS D series, C series forms are similar to MAGFIT EX 600 keeper.

Fig. 4 and 5 demonstrate the overlap in shape between the keeper and magnetic assembly of each test sample. In D 400 and D 600, the area of the keeper was larger in the major axis direction.

In D 800 and D 1000, magnetic assemblies completely covered keepers. (Fig.4).

In C 300, the area of the keeper was lager than that of magnetic assembly.

In C 400, the minor axes had the same length between the keeper and magnetic assembly, and the major axis of the keeper was slightly longer that of magnetic assembly.

In C 600, magnetic assembly completely covered the keeper (Fig. 5).

RESULTS

The horizontal axis shows the types of magnetic assemblies and the vertical axis shows attractive force. The schematic view under the graph shows the overlap when we put GIGAUSS on MAGFIT EX 600 keeper. (Fig6)

All measured value

We obtained values with small standard deviations by using the custom order JIG. These values are considered reproducible.

GIGAUSS D SERIES

In D 400, a value close to the attractive force of a similar combination was obtained. We confirmed significant differences in D 600, D 800, and D 1000.

GIGAUSS C SERIES

In the C series, the value close to the attractive force of a similar combination was obtained in C300, C400, and C600.

DISCUSSION

We compared the attractive force of similar maker combination ( Magnet Assembly — GIGAUSS Keeper — GIGAUSS ) with that of different maker combination ( Magnet Assembly — GIGAUSS Keeper — MAGFIT EX 600 ) . Based on the comparison results, we examined and observed that how much of the original performance of magnetic assembly ( GIGAUSS ) has shown.

In the C series, the external form of keeper and magnetic assembly resembled in shape compared with the D series, and thus showed superior magnetic assembly performance. This is considered to be due to the fact that a magnetic assembly was adsorbed to a keeper without any magnetic force leaking out.

On the other hand, in the D series (D 800, D 1000), the size of a magnetic assembly was greatly larger than the outer contour of a keeper, and the attractive force that magnetic assembly can exert was not observed. This is considered to be due to the fact that the keeper was not able to adsorb a large quantity of magnetic force given by magnetic assemblies D 800, D 1000.

CONCLUSION

In the case of using GIGAUSS D400 or C series for MAGFIT EX 600 keeper, it is suggested that high performance of magnetic assembly can be achieved without magnetic flux leakage by using D 400 or C series in consideration of the size of magnetic assemblies.

REFERENCES

1. Tanaka, Y.: Dental Magnetic Attachment - new prothodontic treatment used the magnet -, Ishiyaku Publishers, Inc. (Tokyo), 1992.

2. Tanaka, Y.: Magfit System - the main point of clinical utilization -, DentalDiamond Co. (Tokyo), 1993.

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

Discussion Board