Department of Conservative Dentistry and Endodontics, A B Shetty Memorial Institute of Dental Science, Nitte University, Mangalore, Karnataka, India.
Department of Conservative Dentistry and Endodontics, A B Shetty Memorial Institute of Dental Science, Nitte University, Mangalore, Karnataka, India.
J Endod. 2021 May;47(5):787-792. doi: 10.1016/j.joen.2021.01.011. Epub 2021 Feb 6.
The butterfly effect is an optical phenomenon and is related to the presence of sclerotic dentin in the roots. The unique pattern of sclerotic dentin formation produces a characteristic butterfly shape in transverse sections of the roots. The objective of this study was to evaluate the direction of the fracture line in roots that exhibit the butterfly effect.
Thirty single-rooted premolars with oval-shaped roots were decoronated and embedded in acrylic blocks and subjected to vertical force under a universal testing machine (HPBSD; Tec-Sol India, Chennai, India). Fractured roots were examined under a stereomicroscope (Model no. 080772; Lawrence and Mayo, Mumbai, India) at ×10 magnification to determine the location and direction of the fracture line. To evaluate the correlation between the direction of sclerotic dentin and the direction of the fracture line, teeth were sectioned and observed under a stereomicroscope at ×20 and ×40 magnification. The correlation was analyzed using the Fisher exact test (P < .05 for the coronal and apical thirds and P > .05 for the middle third).
Sclerotic dentin was observed more in the apical area and less in the coronal third of the root. The correlation between the direction of sclerotic dentin and the direction of the fracture line was statistically significant in the coronal and apical thirds of the root.
The vertical root fracture that runs buccolingually is correlated to the harder sclerotic dentin present in the mesiodistal direction.
蝴蝶效应是一种光学现象，与牙根内的硬化牙本质的存在有关。硬化牙本质形成的独特模式在牙根的横截面上产生特征性的蝴蝶形状。本研究的目的是评估具有蝴蝶效应的牙根中骨折线的方向。
将 30 颗具有椭圆形牙根的单根前磨牙进行去冠，并嵌入丙烯酸块中，然后在万能试验机（HPBSD；Tec-Sol India，Chennai，India）下施加垂直力。在立体显微镜（Model no. 080772；Lawrence and Mayo，Mumbai，India）下以 ×10 放大倍数检查断裂的牙根，以确定骨折线的位置和方向。为了评估硬化牙本质的方向与骨折线的方向之间的相关性，将牙齿进行切片并在立体显微镜下以 ×20 和 ×40 放大倍数进行观察。使用 Fisher 确切检验（根尖和冠三分之一处 P <.05，根中三分之一处 P >.05）分析相关性。
硬化牙本质在根尖区域更为常见，而在根冠三分之一处较少见。在牙根的冠部和根尖三分之一处，硬化牙本质的方向与骨折线的方向之间存在统计学显著相关性。
沿颊舌方向运行的垂直根折与存在于近远中方向的较硬的硬化牙本质相关。
