インプラントにおける磁性アタッチメントの応用

―第3報　各種インプラント対応オーバーデンチャー用キャップ式磁性アタッチメント（MACS）の検討―

抄録

For design of the superstructure of implants, overdentures are regarded as an indispensable alternative in the aspects of lip-support, speech, cleansability, economy, and aesthetics. As a retainer of overdentures, magnetic attachments have attracted attention due to their many useful aspects; for example, they can reduce lateral adverse force.
We have developed various types of Magnetic Attachments of a Cap Shape (MACS) that can be applicable to implants. We applied them in many clinical cases, obtaining good results. In this study, for further detailed evaluation of three types of MACS, such as those applied to ITI, POI, and 3i, among various types of MACS applied to implants used in overdentures, we examined the fit, using a scanning electron microscope (SEM) and a retentive force test using dental force gauges, and evaluated the results with those of the clinical application of MACS. MACS applied to various types of implants used in overdentures are composed of a removable keeper that is directly connectable to the fixture or component using screws, and of a magnet that has a resin cap to cover the keeper.
As a result, the three types of MACS showed good of fit by SEM observation. Regarding measurements by the retentive force test, 772.6 gf was measured in the MACS applied to ITI, 760.3 gf in that applied to POI, and 448.7 gf in that applied to 3i, showing sufficient suction force in all three types. As a result of clinical application of MACS, dislocation due to an improperly installed magnet, and falling of the magnet in later days, were prevented. Moreover, the magnet attachments were applicable to implants with a simple manipulation using self-curing resin without complicated laboratory procedure, and were excellent in retention force, feeling of use, and maintenance, showing a good clinical course. Because the keeper was removable, it was considered that adverse effects on magnetic resonance imaging (MRI), and deterioration of the keeper due to casting or treatment with acids, were prevented. From these results, it was suggested that MACS may have useful applicability for implant overdentures.