牙体裂纹产生机制的扩展有限元分析和生物力学研究

Dental hard tissue damage represented by cracked teeth and tooth fracture, which are of common oral diseases, can affect the dental pulp and periodontal health as an "invisible killer." Recently, researches on cracked teeth were mostly based on in vitro experiments. Related factors and mechanism which affect the emergence and development of cracks remained unclear. Tooth is a biomechanical structure. The emergence and development of cracks in the tooth can be influenced by its macro and micro structure, bite force acting position and direction. Our previous study revealed that diameter and thickness of enamel and dentin can affect tooth structure flexural strength and crack occurrence position. Thus, our group proposed the possible mechanism of generation and development of tooth crack: bite force acting position and orientation can affect the initial crack direction. Diameter, thickness, height and inclination on the cusp of enamel and dentin can affect tooth structure flexural strength. The microstructure and toughening mechanisms of enamel and dentin can influence the direction of crack propagation. Our research builds the macro and micro model of dental hard tissue by extended finite element method to simulate the generation and development of tooth cracks. In vitro study will also be conducted to analyze the relating factors on cracks to provide reference for prevention and treatment of cracked teeth and tooth fracture.

以牙隐裂、牙折裂为代表的牙体硬组织损伤，是口腔常见病之一，是影响牙体牙髓和牙周健康的“隐形杀手”。目前，关于牙体裂纹的研究多基于体外实验，影响其产生和发展的相关因素和作用机制尚不清楚。牙齿作为一生物力学结构，其宏观、微观结构，及咬合力作用位置和方向均可影响牙体裂纹的产生和发展。课题组前期研究也发现，釉质、牙本质直径和厚度对牙体组织抗折强度和裂纹发生位置均有影响。因此，本课题组提出了牙体裂纹可能的产生和发展机制：咬合力作用位置和方向决定牙釉质初始裂纹方向，牙釉质、牙本质直径、厚度、高度及牙尖斜度影响牙体的抗折强度，牙釉质、牙本质微观结构和增韧机制影响裂纹扩展方向。本课题拟通过扩展有限元法构建牙体硬组织宏观、微观模型，模拟牙体裂纹的产生和发展，同时合并体外抗折实验研究相关因素在牙体硬组织裂纹产生和发展中的作用和机制，以期为临床牙隐裂和折裂的预防与治疗提供参考。

以牙隐裂、牙折裂为代表的牙体硬组织损伤,是口腔常见病之一。目前,关于牙体裂纹的研究多基于体外实验,影响其产生和发展的相关因素和作用机制尚不清楚。课题组采用简化的模型和扩展有限元法研究牙釉质、牙本质直径、厚度、高度对牙体抗折强度的影响，同时合并体外实验验证有限元研究的准确性。模拟上颌第一磨牙裂纹产生于牙冠釉质的近中沟，并沿近中沟逐渐向中央窝、近中窝、近中边缘嵴及远中窝扩展，最终随着载荷增加而引发牙本质的折裂。同时结合临床，研究开髓洞型和修复体类型对上颌第一磨牙和上颌第一前磨牙抗折强度的影响，以及裂纹产生和扩展模式。在着眼于宏观折裂的同时，通过体外实验研究牙釉质断裂韧性，并结合有限元模拟微观牙釉质结构破坏过程。本课题通过扩展有限元法模拟牙体裂纹的产生和发展，合并体外实验，研究牙体硬组织裂纹产生和发展的相关宏观因素和微观因素，以期为临床牙隐裂和折裂的预防与治疗提供参考。