各种类型的活动矫正器对狭窄牙弓的开展已取得一些进展,用于开展上牙弓的大多数活动矫正器是由埋在硬橡胶托内的Coffin氏圈演变改进而来的(图1.A)。尽管该矫正器是定期加力,因有腭部复合圈的结构,所以产生的力是持续性的。开展牙弓用的最普通的一种活动矫正器是由Martin和Schwarz提出的。此矫正器利 Various types of active braces have made some progress in the development of stenosed dental arch. Most of the braces used to perform the upper arch are modified from the Coffin's ring embedded in a hard rubber bracket (Figure 1 .A). Although the appliance is periodically energized, the resulting force is constant due to the structure of the palatal ring. The most common type of activity braces used for dental arch is made by Martin and Schwarz. This appliance is beneficial