Liu Zong Xiang, Liu Yi, Ww Chang Jeffrey, Yuan Chang Yong, Zhang Cheng Fei, Wang Peng Lai
Chin J Dent Res. 2014;17(2):111-6.
To evaluate morphological changes of the apical surface after root canal preparation with 1 mm beyond the apical foramen using ProTaper Universal (PTU) files, K3 files and Twisted files (TF), respectively.
Seventy teeth with a centered apical foramen and 70 teeth with a deviated apical foramen were included as group A and group B respectively. In each group, 20 teeth were randomly assigned for root canal preparation with PTU, K3 and TF files, respectively; the remaining 10 teeth were used as the control group without any preparation. The apical foramens were examined with scanning electronic microscopy. The foramen integrity damage (FID) and dentin defects (DDs) were noted and compared between different groups.
FID and DD were significantly less in Group A. DDs was not found in the control group. Preparation with PTU, K3, and TF files caused FID in 6.67%, 10%, and 3.33% of teeth in the group A, and in 20%, 26.67%, and 10% in Group B, respectively. Preparation with PTU, K3, and TF files caused DD in 6.67%, 6.67%, and 3.33% of teeth in Group A, and in 23.33%, 26.67%, and 6.67% in Group B, respectively. PTU and K3 files produced more DDS than TF files. However, no significant difference was found between groups using PTU and K3 files.
Rotary instrumentation caused less damage on the apical surface in foramencentered root canals than foramen-deviated root canals when working beyond the canal length. TF files had a tendency to produce less DDS compared with PTU or K3 files during over-instrumented root canals.
分别评估使用ProTaper Universal（PTU）锉、K3锉和Twisted锉（TF）进行根管预备至根尖孔外1mm后根尖表面的形态学变化。
分别纳入70颗根尖孔居中的牙齿和70颗根尖孔偏移的牙齿作为A组和B组。每组中，20颗牙齿分别随机分配用PTU锉、K3锉和TF锉进行根管预备；其余10颗牙齿作为未做任何预备的对照组。用扫描电子显微镜检查根尖孔。记录并比较不同组之间的孔完整性损伤（FID）和牙本质缺损（DDs）情况。
A组的FID和DD明显更少。对照组未发现DDs。在A组中，用PTU锉、K3锉和TF锉预备分别导致6.67%、10%和3.33%的牙齿出现FID，在B组中分别为20%、26.67%和10%。在A组中，用PTU锉、K3锉和TF锉预备分别导致6.67%、6.67%和3.33%的牙齿出现DD，在B组中分别为23.33%、26.67%和6.67%。PTU锉和K3锉产生的DDs比TF锉更多。然而，使用PTU锉和K3锉的组之间未发现显著差异。
当根管预备超出根管长度时，旋转器械对根尖孔居中的根管根尖表面造成的损伤小于根尖孔偏移的根管。在过度预备的根管中，与PTU锉或K3锉相比，TF锉产生DDs的倾向更小。
