As for static frictional resistance , the optimal combination of archwire , brackets and time was : 3M MBT bracket, 0.018 inch stainless steel round wire and at the 30th day under artificial saliva condition and at 370C ;

• 就静摩擦力而言，最佳组合为：3M MBT托槽，0.；018英寸不锈钢圆丝，人工唾液作用时间为30天；