| Magnetic retainer is a kind of attachment to aid retention of prostheses, and developed in recent years. Several types of magnetic retainers have been used for oral and maxillofacial prostheses and made the retentive foroe increase notably. It is becoming an important retentive way for improving retention of prostheses. However, there are some disadvantages which have been found in magnetic retiners used now, such as no enough retentive force; heat-demagnetizing and demagnetized by magnet corrosion etc. So, it is necessary to find a new type magnetic retainer with stronger retentive force, good heat stability and excellent anticorrosive ability. Meanwhile, to valuate the real applying effect of magnetic retainer is significant for popularizing the application of magnetic retainers.The influential factors of magnetic retainer were observed and analyzed in our experiments. These factors include: the property of magnetic materials', materials matching rate; designing forms of retainer; corrosion of magnetic materiats erc. The results show that:1. Rerentive force of magnetic retainer is affected directly by magnetic properties and heat stability of permanent magnet. BGH-1 NdFeB magnet has the highest magnetic property and the best heat stability among many types of magnets.2. None of cytotoxicity was found in FeCrMo soft magnetic alloy, the good biocompability and better magnetic property made this alloy be utilized for fabricating the components of magnetic retainer.3. Very different Retentive force was found in different designed retainers. Closed-field magnetic retainer can gain stronger retentive force than open-tield magnetic retainer in same volume. The strongest magnetic retentive force is got by "sandwich" design in minimun volume among 5... |
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