Methods The expanders were divided into two groups, the normal expansion and the continuous and constant pressure expansion (4.6 kPa).

• 方法在扩张囊内注入0.；2%25甲硝唑后分为常量扩张组和持续恒压扩张组；将扩张囊置入生理盐水中；分别于1、2、4、8、12、24、48及72小时取样；测定囊外的药物浓度。