Gillings B R
Int Dent J. 1984 Sep;34(3):184-97.
A magnetic retention system has been used in more than 6000 complete and partial overdentures, sectional dentures and implant overdentures, with excellent clinical results and patient acceptability. For the overdenture application, decoronated, root-treated teeth are fitted with preformed or cast magnetisable alloy root elements, or 'keepers'. Following conventional denture construction, paired cobalt/samarium magnets in a special configuration are cured into the denture base so that with the denture inserted, the magnets grip the root elements with a retentive force of approximately 300 g per root. The paired magnet arrangement eliminates any external magnetic field and doubles the available retention. Magnetic retention has few of the problems encountered with other retention devices. It offers simplicity, low cost, self-adjustment, inherent stress-breaking, automatic repositioning after denture displacement, comparative freedom of lateral denture movement, reduces trauma to retained roots and eliminates the need for adjustment in service. For the sectional denture application, undesirable undercuts on the abutment teeth are used to provide passive, positive retention. The separate buccal and lingual sections are joined together by parallel pins fitting into matching tubes, assembly being maintained by magnetic attraction between a retention element in one section and a keeper in the other. Insertion and removal are more difficult than with a conventional denture but soft tissue coverage is minimal. There are no visible retainer arms and food traps are eliminated. Abutment tooth preparation is negligible, the laboratory procedures simple, and the treatment inexpensive and reversible. A clinical trial of magnetic overdenture retention in conjunction with osseointegrated titanium implants is now in progress. After 21 months acceptable clinical results have been obtained. An improved implant with an alumina core and a sintered hydroxyapatite coating is at present undergoing animal trials. Chemical bonding at the bone/implant interface is anticipated.
一种磁性固位系统已应用于6000多例全口和局部覆盖义齿、分段义齿及种植覆盖义齿，临床效果极佳，患者接受度高。对于覆盖义齿应用，经过去冠、根管治疗的牙齿安装预制或铸造的可磁化合金牙根部件，即“固位体”。按照传统义齿制作方法，将特殊配置的成对钴/钐磁体固化到义齿基托中，这样在义齿就位时，磁体以每根牙根约300克的固位力夹住牙根部件。成对磁体排列消除了任何外部磁场，并使可用固位力加倍。磁性固位几乎没有其他固位装置所遇到的问题。它具有简单、成本低、自我调整、固有应力断裂、义齿移位后自动复位、义齿侧向移动相对自由、减少对保留牙根的创伤以及无需在使用中进行调整等优点。对于分段义齿应用，利用基牙上不理想的倒凹来提供被动、可靠的固位。单独的颊侧和舌侧部分通过插入匹配管中的平行销连接在一起，通过一部分中的固位元件与另一部分中的固位体之间的磁吸引力保持组装。插入和取出比传统义齿更困难，但软组织覆盖最小。没有可见的固位臂，消除了食物滞留问题。基牙预备可忽略不计，实验室操作简单，治疗成本低且可逆转。一项关于磁性覆盖义齿固位与骨结合钛种植体联合应用的临床试验正在进行中。21个月后已获得可接受的临床结果。一种改进的带有氧化铝芯和烧结羟基磷灰石涂层的种植体目前正在进行动物试验。预计在骨/种植体界面会发生化学键合。
