Research on the clinical application of a dental magnetic attachment

目前市场上有几种类型的牙科磁性附着体，但没有一种是临床上令人满意的。一个问题是它们太大，否则保持力太弱。此外，它们中的大多数不具有足够的耐腐蚀性，这是临床使用的关键点。通过设计一种夹层结构和椭圆形截面，并借助三维有限元分析，研制了一种体积小、功能强的附着体。附件采用激光焊接到轭上的不锈钢帽密封。在临床试验中显示出足够的吸引力和稳定性。建立光弹性模拟模型，研究游离端可摘局部义齿下粘膜和骨组织的连续应力分布。将我们研制的磁性附着体与传统的固位体如O形环、钢丝卡环和Bear附着体进行比较。本文通过摄像系统和连续摄影的方法，对双杠杆式义齿基托在垂直载荷作用下产生的光弹性条纹进行了连续观察，虽然还没有得出最终结论，但本研究表明，磁性附着体作为一种新型的义齿固位体，与其他固位体表现出相同的力学状态。这意味着磁性附着体可以在临床上使用，没有任何特殊的焦虑。MAGFIT 600型附着体是日本1992年8月上市的第一种国产附着体，本研究应采用有限元技术进行三维动态分析，以建立确定实际临床指征的基本原则。

Several types of dental magnetic attachment are commercially available at the moment, however none of them are clinically satisfactory. One problem is that they are too large, otherwise the retentive force is too weak. Furthermore, most of them do not have enough corrosion resistance, which is a crucial point in clinical use. A very small and powerful attachment has been developed by devicing a sandwich typed construction and the elliptic cross-section with aid of three dimentional FEM analysis. The attachment is sealed with a stainless steel cap laser-welded to the yoke. It has shown sufficient attractive force and stability in clinical trials. A photoelastic simulation model was fabricated to study the continuous stress distribution in the mucous membrane and the bone under a free- end typed removable partial denture. Our originally developed magnetic attachment was compared with other conventional retainers such as the O-ring attachment, wire clasp and Bear attachment. The photoelastic fringes produced when the vertical loads were applied on the canti-lever denture saddle, were continuously by video system and serial photos.Although a final conclusion has not been determined, it was clarified by this research that a dental magnetic attachment which belongs to quite new category of denture retainers, showed the same mechanical attitude as other retainers. That means the magnetic attachment can be clinically used without any special anxieties. This new attachment of which commercial name is "MAGFIT 600" has benn put on the market in August 1992 as the first domestic product in Japan.This research should be followed by the three-dimentional dynamic analysis by FEM technique to establish a basic principle to determine the actual clinical undications.