Faculty of Dentistry, Department of Endodontics, Ondokuz Mayıs University, Samsun, Turkey.
Int Endod J. 2018 Feb;51(2):240-246. doi: 10.1111/iej.12842. Epub 2017 Sep 15.
To conduct a quantitative and qualitative analysis of the band-shaped isthmus area, the floor of which was in the apical third in the mesial roots of mandibular first molars using micro-computed tomography (micro-CT).
Micro-CT images of 269 mesial roots of mandibular first molars were evaluated, and 40 specimens with a band-shaped isthmus, with a floor in the apical third, were selected. The major diameter, minor diameter, roundness, area and perimeter values for the most coronal and apical slices where the isthmus was visible were measured. The distances between these slices were measured as the isthmus length, and the total volume, structure model index and surface area of the isthmus were measured. The distances between the isthmus floor and two apical foramina and the number of root canal orifices were calculated. The dimensions of the isthmus roof and the floor were compared, and the data were analysed using descriptive statistics and Student's t-tests with a significance threshold set at 5%.
A total of 15% of the specimens had band-shaped isthmuses with a floor in the apical third. The isthmus roof exhibited significantly greater major and minor diameter values compared to the isthmus floor (P < 0.05). No significant difference was detected between the isthmus roof and the floor with regard to roundness (P > 0.05).
Three- and two-dimensional analyses of the mesial roots of mandibular molars revealed that band-shaped isthmuses had complex shapes.
使用微计算机断层扫描（micro-CT）对下颌第一磨牙近中根内带状峡部的底部位于根尖三分之一处进行定量和定性分析。
评估了 269 个下颌第一磨牙近中根的 micro-CT 图像，选择了 40 个具有带状峡部且底部位于根尖三分之一处的标本。测量峡部最冠和最根尖可见切片的长轴直径、短轴直径、圆度、面积和周长值。测量这些切片之间的距离作为峡部长度，并测量峡部的总体积、结构模型指数和表面积。计算峡部底部与两个根尖孔之间的距离和根管口的数量。比较峡部屋顶和地板的尺寸，并使用描述性统计和学生 t 检验分析数据，显著性水平设为 5%。
共有 15%的标本具有底部位于根尖三分之一处的带状峡部。峡部屋顶的长轴和短轴直径值明显大于峡部地板（P<0.05）。峡部屋顶和地板的圆度之间没有显著差异（P>0.05）。
对下颌磨牙近中根的三维和二维分析表明，带状峡部具有复杂的形状。
