Jain Apoorva, Nikhil Vineeta, Bansal Parul
Department of Conservative Dentistry and Endodontics, Subharti Dental College, Meerut, Uttar Pradesh, India.
J Conserv Dent. 2018 Sep-Oct;21(5):521-525. doi: 10.4103/JCD.JCD_184_18.
This study evaluated the effect of root canal preparation, obturation, and different techniques of retreatment on the percentage increase in the number of dentinal microcracks using microcomputed tomography (CT) analysis.
Forty-five mandibular premolars after micro-CT scanning were prepared using Protaper universal files up to F4 and obturated. After the second micro-CT scanning again, the samples were randomly divided into three groups ( = 15) for retreatment procedure. In Group 1, retreatment was done with Protaper universal D1, D2, and D3 retreatment files followed by Protaper universal file till F4. In Group 2, retreatment was performed with R-Endo reciprocating motion, Re, R1, R2, R3, and Rs followed by Hero Shaper size #40. In Group 3, retreatment was performed with H-files and xylene till size #40. After gutta percha removal, the samples were again scanned for micro-CT for the evaluation of percentage increase in dentinal microcracks. Data were analyzed using "Kruskal-Wallis test ANOVA" and "student -test" at 5% level of significance.
Few unprepared samples showed preexisting microcracks. There were statistically significant percentage increase dentinal cracks after root canal preparation and obturation as well as after retreatment procedure with statistically significant percentage increase in the number of dentinal microcracks between all three groups.
Intraradicular procedures such as shaping and cleaning and obturation as well as the use of retreatment file lead to the induction and propagation of dentinal microcracks. In the present study, the maximum microcracks were produced with Protaper universal retreatment file system followed by R-Endo system. H-files produced minimum cracks during retreatment procedures.
本研究采用微型计算机断层扫描（CT）分析，评估根管预备、充填以及不同再治疗技术对牙本质微裂纹数量增加百分比的影响。
45颗下颌前磨牙经微型CT扫描后，使用Protaper通用锉预备至F4并进行充填。再次进行微型CT扫描后，将样本随机分为三组（每组n = 15）进行再治疗。第1组，先用Protaper通用D1、D2和D3再治疗锉进行再治疗，然后用Protaper通用锉预备至F4。第2组，采用R-Endo往复运动器械Re、R1、R2、R3和Rs进行再治疗，随后用Hero Shaper 40号锉。第3组，用H锉和二甲苯预备至40号锉。去除牙胶后，再次对样本进行微型CT扫描，以评估牙本质微裂纹数量的增加百分比。采用“Kruskal-Wallis检验方差分析”和“学生t检验”在5%显著性水平下对数据进行分析。
少数未预备的样本显示存在原有的微裂纹。根管预备、充填后以及再治疗后，牙本质裂纹数量均有统计学意义的增加，且三组之间牙本质微裂纹数量增加百分比具有统计学意义。
根管内操作如根管预备、清洁、充填以及使用再治疗锉会导致牙本质微裂纹的产生和扩展。在本研究中，Protaper通用再治疗锉系统产生的微裂纹最多，其次是R-Endo系统。H锉在再治疗过程中产生的裂纹最少。
