Krishan Rajesh, Paqué Frank, Ossareh Arezou, Kishen Anil, Dao Thuan, Friedman Shimon
Disciplines of Endodontics, University of Toronto, Toronto, Ontario, Canada.
Department of Endodontology, University of Zurich, Zurich, Zurich, Switzerland.
J Endod. 2014 Aug;40(8):1160-6. doi: 10.1016/j.joen.2013.12.012. Epub 2014 Jan 28.
Conservative endodontic cavity (CEC) may improve fracture resistance of teeth but compromise the instrumentation of canals. This study assessed the impacts of CEC on both variables in 3 tooth types.
Extracted human intact maxillary incisors, mandibular premolars, and molars (n = 20/type) were imaged with micro-computed tomographic imaging (20-μm resolution) and assigned to CEC or traditional endodontic cavity (TEC) groups (n = 10/group/type). Minimal CECs were plotted on scanned images. Canals were prepared with WaveOne instruments (Dentsply Maillefer, Ballaigues, Switzerland) using 1.25% sodium hypochlorite and post-treatment micro-computed tomographic images obtained. The proportion of the untouched canal wall (UCW) and the dentin volume removed (DVR) for each tooth type was analyzed with the independent-samples t test. The 60 instrumented and 30 intact teeth (negative control, n = 10/type) were loaded to fracture in the Instron Universal Testing machine (Instron, Canton, MA) (1 mm/min), and the data were analyzed with 1-way analysis of variance and the Tukey test.
The mean proportion of UCW was significantly higher (P < .04) only in the distal canals of molars with CEC (57.2% ± 21.7%) compared with TEC (36.7% ± 17.2%). The mean DVR was significantly smaller (P < .003) for CEC than for TEC in incisors (16.09 ± 4.66 vs 23.24 ± 3.38 mm(3)), premolars (8.24 ± 1.64 vs 14.59 ± 4.85 mm(3)), and molars (33.37 ± 67.71 mm(3)). The mean load at fracture for CEC was significantly higher (P < .05) than for TEC in premolars (586.8 ± 116.9 vs 328.4 ± 56.7 N) and molars (1586.9 ± 196.8 vs 641.7 ± 62.0 N). In both tooth types, CEC did not differ significantly from the negative controls.
Although CEC was associated with the risk of compromised canal instrumentation only in the molar distal canals, it conserved coronal dentin in the 3 tooth types and conveyed a benefit of increased fracture resistance in mandibular molars and premolars.
保守性牙髓腔（CEC）可能会提高牙齿的抗折性，但会影响根管预备。本研究评估了CEC对三种牙齿类型的这两个变量的影响。
对拔除的完整人类上颌切牙、下颌前磨牙和磨牙（每种类型n = 20）进行显微计算机断层扫描成像（分辨率20μm），并分为CEC组或传统牙髓腔（TEC）组（每组每种类型n = 10）。在扫描图像上绘制最小的CEC。使用WaveOne器械（登士柏迈弗，瑞士巴拉伊格），用1.25%次氯酸钠预备根管，并获得治疗后的显微计算机断层扫描图像。用独立样本t检验分析每种牙齿类型未触及的根管壁（UCW）比例和去除的牙本质体积（DVR）。将60颗预备根管的牙齿和30颗完整牙齿（阴性对照，每种类型n = 10）在英斯特朗万能试验机（英斯特朗，马萨诸塞州坎顿）中加载至折断（1 mm/min），并用单因素方差分析和Tukey检验分析数据。
与TEC（36.7%±17.2%）相比，仅CEC组磨牙远中根管的UCW平均比例显著更高（P <.04）（57.2%±21.7%）。CEC组的平均DVR在切牙（16.09±4.66 vs 23.24±3.38 mm³）、前磨牙（8.24±1.64 vs 14.59±4.85 mm³）和磨牙（33.37±67.71 mm³）中显著小于TEC组。CEC组前磨牙（586.8±116.9 vs 328.
