间接粘结中托槽转移精确度的比较

Comparision of bracket transfer accuracy of indirect bonding methods

目的 比较间接粘结技术中使用两种不同转移托盘及不同牙列拥挤度时的托槽转移精确度.方法 收集30名患者的上颌或下颌硬石膏模型,各取2付,在之后的托槽转移步骤中根据用单层膜片和双层膜片制作间接粘结的转移托盘,分为A、B两组;根据其牙列拥挤度、1为轻度及以下拥挤,2为中度拥挤,再分为A1、A2、B1、B2组,每组中各有15付模型.模型上粘结托槽后经CBCT扫描并重建数字化三维模型,分别用单层膜片（A1、A2组）和双层膜片（B1、B2组）制作间接粘结的转移托盘,将转移托盘重新放回初始模型完成托槽粘结,再次经过CBCT扫描并重建数字化三维模型,通过Geomagic软件比对前后的数字模型,比较托槽位置在转移过程中的变化程度.结果 托槽转移前后的最大距离及平均距离各组之间无统计学差异（P＞0.05）,B组平均距离的标准差大于A组,且差异有统计学意义（P＜0.05）.B2组平均距离的标准差大于A1、A2、B1组,差异有统计学意义（P＜0.05）.结论 使用单层膜片和双层膜片的间接粘结技术托槽转移精确度无显著差异,单层膜片的稳定性更佳;牙列拥挤度增大会使托槽转移的稳定性下降.

Objective To compare bracket transfer accuracy of indirect bonding method using two different transfer trays with different dental crowding conditions.Methods Casts of 30 patients were collected.Each casts was impressed twice and the casts were grouped into A and B.According to crowding degrees,casts were grouped into A1,A2,B1 and B2 （n =15）.A1 and B1 were mild crowding groups,while A2 and B2 were moderate crowding groups.Casts with brackets were scanned using CBCT and 3D reconstructed using Mimics software.Indirect bonding transfer trays for group A and B were made with one-layer film and bilayer films,separately.Transfer trays were put on to initial casts to complete bonding.Casts were scanned and 3D reconstructed again using CBCT and Mimics,and images were imported into Geomagic Studio software for superimposition and analysis to compare the change of brackets position during transfer.Results The maximum distance and average distance of brackets movement before and after transfer have no statistical significance among different groups （P〉0.05）.The standard deviation of average distance of group B is greater than group A,with statistically significant differences （P〈0.05）.The standard deviation of average distance of group B2 is greater than group A1,A2 and B1,with statistically significant differences （P 〈 0.05）.Conclusions The braceket transfer accuracy of indirect bonding methods difference between using one-layer film and bilayer films has no statistical difference,while the stability is better by using onelayer film.Increased degree of crowding may reduce the stability of brackets transfer.