两种牙科磁性附着体静磁场磁通密度和固位力的测定  

Measurements of the Flux Densities of Static Magnetic Fields Generated by Two Types of Dental Magnetic Attachments and Their Retentive Forces

作　　者：胥春 巢永烈[1] 杜莉[1] 杨凌[1] 

机构地区：[1]四川大学华西口腔医学院口腔修复学教研室

出　　处：《四川大学学报（医学版）》2004年第3期412-415,共4页Journal of Sichuan University(Medical Sciences)

基　　金：四川省科委应用基础研究基金 (项目号 :0 2 sy0 2 9.13 8)资助

摘　　要：目的　测定、分析 MAGNEDISC80 0 (MD80 0 )、MAGFIT EX6 0 0 W(EX6 0 0 )这两种常用牙科磁性附着体的静磁场磁通密度和固位力 ,为磁性附着体的临床应用提供指导。方法　采用数字高斯计分别测定开放磁路、闭合磁路下以及模拟临床情况将衔铁与磁体水平错开一定距离、衔铁与磁体垂直拉开一定距离时 ,两种磁性附着体静磁场磁通密度。采用拉力试验机测定标准闭合磁路下以及模拟临床情况将衔铁与磁体水平错开一定距离、衔铁与磁体垂直拉开一定距离时 ,两种磁性附着体的固位力值。结果　两种磁性附着体在开放磁路、闭合磁路下均存在漏磁 ,MD80 0、EX6 0 0在开放磁路下磁体表面的磁通密度分别达 2 75 .0 m T、14 7.0 m T,闭合磁路下两种附着体的漏磁量均明显下降 ,相应表面磁通密度分别减小为 11.4 m T、4 .5 m T,附着体周围磁通密度随距附着体表面距离的增大而递减。当附着体衔铁与磁体水平错开或垂直拉开一定距离时漏磁量增大。两种磁性附着体在标准闭合磁路下其固位力值最大 ,MD80 0、EX6 0 0分别为 6 .2 0 N和 4 .80 N ,随衔铁与磁体水平错开或垂直拉开距离的增大其固位力值逐渐减小。结论　磁性附着体存在一定的漏磁 ,当其应用于患者口腔中时 ,若衔铁与磁体未完全对位 ,漏磁量将增大 ,同时附着体固位力减?Objective To measure and analyze the flux densities of static magnetic fields generated by two types of commonly used dental magnetic attachments and their retentive forces, and to provide guidance for the clinical application of magnetic attachments. Methods A digital Gaussmeter was used to measure the flux densities of static magnetic fields generated by two types of magnetic attachments, under four circumstances: open-field circuit; closed-field circuit; keeper and magnet slid laterally for a certain distance; and existence of air gap between keeper and magnet. The retentive forces of the magnetic attachments in standard closed-field circuit, with the keeper and magnet sliding laterally for a certain distance or with a certain air gap between keeper and magnet were measured by a tensile testing machine. Results There were flux leakages under both the open-field circuit and closed-field circuit of the two types of magnetic attachments. The flux densities on the surfaces of MAGNEDISC 800 (MD800) and MAGFIT EX600W (EX600) magnetic attachments under open-field circuit were 275.0 mT and 147.0 mT respectively. The flux leakages under closed-field circuit were smaller than those under open-field circuit. The respective flux densities on the surfaces of MD800 and EX600 magnetic attachments decreased to 11.4 mT and 4.5 mT under closed-field circuit. The flux density around the magnetic attachment decreased as the distance from the surface of the attachment increased. When keeper and magnet slid laterally for a certain distance or when air gap existed between keeper and magnet, the flux leakage increased in comparison with that under closed-field circuit. Under the standard closed-field circuit, the two types of magnetic attachments achieved the largest retentive forces. The retentive forces of MD800 and EX600 magnetic attachments under the standard closed-field circuit were 6.20 N and 4.80 N respectively. The retentive forces decreased with the sliding distance or with the increase of air gap between keeper and magn

关 键 词：磁性附着体 静磁场 磁通密度 固位力 

分 类 号：R783.6[医药卫生—口腔医学]