Priyank Harsh, Pandey Vinisha, Sethi Achla, Sharma Vinay J, Bali Harleen, Punia Ramandeep S
Department of Conservative Dentistry and Endodontics Hazaribag College of Dental Sciences and Hospital, Hazaribagh Jharkhand, India, Phone: +919501544877, e-mail:
Department of Conservative Dentistry and Endodontics, Institute of Dental Studies & Technologies, Modinagar, Uttar Pradesh, India.
J Contemp Dent Pract. 2017 Sep 1;18(9):826-830. doi: 10.5005/jp-journals-10024-2134.
Cleaning and shaping of the pulp canal is one of the most important steps of endodontic therapy. Serious complications occur by the apical extrusion of bacteria during the instrumentation procedures. Both crown-down (CD) and full-length linear motion (FM) techniques are routinely used as a component of taper rotary instrument procedures for achievement of thorough cleaning and shaping of the pulp canal space. Hence, we aimed for this study to assess the change in the amount of apically extruded bacteria using CD and FM instrumentation techniques produced by differences in taper between the instruments used during biomechanical preparation of root canals.
The present study included assessments of 132 extracted maxillary central incisor teeth. To achieve a uniform teeth length of 21 mm, the height of the tooth crown was reduced for preserving the coronal portion of teeth. A modified glass vial model was constructed for the estimation of amount of bacterial extrusion through the apical region. For filling of each pulp canal specimen, 20 mL of Enterococcus faecalis suspension was used followed by the use of a number 10 K-file for carrying the bacteria down the lengths of pulp canals. All the contaminated teeth specimens were divided into six study groups with groups I to III containing specimens prepared in the CD manner, while groups IV to VI contained specimens prepared in the FM manner. Six teeth were taken as negative control with three specimens with each technique, and another six specimens were taken as positive controls. Cultivable bacterial counts were determined by evaluating 100 mL saline solution from each vial followed by its inoculation on blood agar. All the colony-forming unit (CFU) values were log-transformed (base 10), and the results were analyzed by Statistical Package for the Social Sciences software.
A significantly lower quantity of CFU values was observed during CD instrumentation procedures with 0.02 files in comparison with all other study groups. However, while comparing both the instrumentation procedures when different taper files, other than 0.02 taper, were used for biomechanical preparation of root canal, nonsignificant results were obtained.
With 0.02 taper preparations, significantly less amount of extrusion of bacteria is associated when done with CD technique.
No change in the amount of apical extrusion of bacteria will be seen by changing the type of instrumentation procedures. Amount of bacteria extruded can be minimized using 0.02 taper. Key words: Bacteria, Instrumentation, Taper.
牙髓腔的清理和塑形是牙髓治疗最重要的步骤之一。在根管预备过程中，细菌的根尖挤出会引发严重并发症。冠向下（CD）技术和全长直线运动（FM）技术都是常规用于根管预备的锥形旋转器械操作的组成部分，目的是实现牙髓腔的彻底清理和塑形。因此，本研究旨在评估使用CD和FM器械操作技术时，由于根管生物力学预备过程中所用器械锥度不同而导致的根尖挤出细菌量的变化。
本研究对132颗拔除的上颌中切牙进行评估。为使牙齿长度统一为21mm，降低牙冠高度以保留牙齿的冠部。构建一个改良的玻璃瓶模型，用于估计通过根尖区域挤出的细菌量。对于每个牙髓腔标本的填充，使用20mL粪肠球菌悬液，然后使用10号K锉将细菌带入牙髓腔。所有受污染的牙齿标本被分为六个研究组，第一组至第三组包含以CD方式制备的标本，而第四组至第六组包含以FM方式制备的标本。每组取六颗牙齿作为阴性对照，每种技术各三个标本，另外六个标本作为阳性对照。通过评估每个玻璃瓶中的100mL盐溶液，然后将其接种在血琼脂上，来确定可培养细菌计数。所有菌落形成单位（CFU）值进行对数转换（以10为底），结果使用社会科学统计软件包进行分析。
与所有其他研究组相比，使用0.02锥度锉进行CD器械操作时观察到的CFU值显著更低。然而，当比较使用除0.02锥度以外的不同锥度锉进行根管生物力学预备的两种器械操作时，结果无显著差异。
使用0.02锥度预备时，采用CD技术进行操作时细菌挤出量显著更少。
改变器械操作类型不会使根尖细菌挤出量发生变化。使用0.02锥度可使挤出的细菌量最小化。关键词：细菌；器械操作；锥度
