Apical Displacement and Residual Root Canal Filling with Single-Cone After Post Space Preparation: A Micro-CT Analysis

Abstract The purpose of this study was to evaluate the presence of residues after post space preparation (PSP) and establish whether the apical displacement of the gutta-percha was affected by the moments and methods of PSP in teeth filled by the single-cone technique. The root canals of 20 bovine incisor teeth were instrumented with Reciproc and filled with single-cone and AH Plus. The specimens were divided into 4 groups according to the moment and method of PSP (n=5): immediate with drill, immediate with thermoplasticizer, delayed with drill and delayed with thermoplasticizer. Micro-CT scans were performed before and after the PSP for residues of the root canal filling (1) and analysis of apical displacement (2). Data were analyzed by using 2-way repeated measurement ANOVA (1) and 2-way ANOVA (2) followed by the Tukey’s test (a=0.05). Significance effect on the residues percentage remaining for methods (p=0.044), for moments (p=0.006), for thirds repetition (p<0.001), and for interaction between methods and thirds (p<0.001), and moments and thirds (p=0.044). Significance effect on the apical displacement of root canal filing was detected for methods (p=0.008), however no difference was found between moments (p=0.617). In general, PSP using drill resulted in more homogeneous root canal preparation, mainly when made immediately. For all other combinations between methods and moments for PSP, the middle and apical thirds presented significant higher residues remaining. Thermo method performed in both moments and the drill method performed immediately had displacement in the apical direction, representing extrusion of the root filling material.

摘要 本研究旨在评估桩道预备（post space preparation，PSP）后根管充填残留情况，并明确采用单尖法充填的患牙中，牙胶尖的根尖移位是否受PSP的时机与操作方式影响。本研究选取20颗牛切牙的根管，使用Reciproc锉进行根管预备，采用单尖法结合AH Plus根管封闭剂完成根管充填。将标本按PSP的时机与操作方式分为4组（n=5）：即刻车针组、即刻热塑剂组、延迟车针组、延迟热塑剂组。分别在PSP前后进行显微计算机断层扫描（micro-CT），以（1）检测根管充填物残留情况，（2）分析根尖移位情况。采用双向重复测量方差分析（1）与双向方差分析（2）结合Tukey检验（α=0.05）对数据进行分析。结果显示，充填物残留百分比在不同预备方式（p=0.044）、不同预备时机（p=0.006）、不同根管分段（p<0.001），以及预备方式与根管分段的交互作用（p<0.001）、预备时机与根管分段的交互作用（p=0.044）上存在显著差异。针对根管充填物根尖移位的分析显示，不同预备方式存在显著影响（p=0.008），但不同预备时机无显著差异（p=0.617）。总体而言，使用车针进行PSP可获得更均匀的根管预备效果，尤以即刻操作为佳。其余所有PSP方式与时机的组合中，根中段与根尖段的残留充填物占比显著更高。两种时机下的热塑法与即刻车针法均会导致根尖向移位，即根管充填材料被挤出。