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Abstract：
OBJECTIVE: To evaluate the effect of the labiolingual diameter and construction of an endodontically treated (ET) anterior tooth with crown restoration on stress distribution and biomechanical safety under occlusal loading.
METHODS: Three-dimensional finite element models were generated for maxillary central incisors with all-ceramic crown restorations. The labiolingual diameters of the tooth, defined as the horizontal distance between the protrusion of the labial and lingual surfaces, were changed as follows: (D1) 6.85 mm, (D2) 6.35 mm, and (D3) 5.85 mm. The model was constructed as follows: (S0) vital pulp tooth; (S1) ET tooth; (S2) ET tooth with a 2 mm ferrule, restored with a fiber post and composite resin core; (S3) ET tooth without a ferrule, restored with a fiber post and composite resin core. A total of 12 models were developed. In total, two force loads (100 N) were applied to the crown\'s incisal edge and palatal surface at a 45° oblique angle to the longitudinal axis of the teeth. The Von Mises stress distribution and maximum stress of the models were analyzed.
RESULTS: Regardless of the loading location, stress concentration and maximum stress (34.07~66.78MPa) in all models occurred in the labial cervical 1/3 of each root. Both labiolingual diameter and construction influenced the maximum stress of the residual tooth tissue, with the impact of the labiolingual diameter being greater. A reduction in labiolingual diameter led to increased maximum stress throughout the tooth. The ferrule reduced the maximum stress of the core of S2 models (7.15~10.69 MPa), which is lower compared with that of S3 models (19.45~43.67 MPa).
CONCLUSIONS: The labiolingual diameter exerts a greater impact on the biomechanical characteristics of ET anterior teeth with crown restoration, surpassing the influence of the construction. The ferrule can reduce the maximum stress of the core and maintain the uniformity of stress distribution.
METHODS: Three-dimensional finite element models were generated for maxillary central incisors with all-ceramic crown restorations. The labiolingual diameters of the tooth, defined as the horizontal distance between the protrusion of the labial and lingual surfaces, were changed as follows: (D1) 6.85 mm, (D2) 6.35 mm, and (D3) 5.85 mm. The model was constructed as follows: (S0) vital pulp tooth; (S1) ET tooth; (S2) ET tooth with a 2 mm ferrule, restored with a fiber post and composite resin core; (S3) ET tooth without a ferrule, restored with a fiber post and composite resin core. A total of 12 models were developed. In total, two force loads (100 N) were applied to the crown\'s incisal edge and palatal surface at a 45° oblique angle to the longitudinal axis of the teeth. The Von Mises stress distribution and maximum stress of the models were analyzed.
RESULTS: Regardless of the loading location, stress concentration and maximum stress (34.07~66.78MPa) in all models occurred in the labial cervical 1/3 of each root. Both labiolingual diameter and construction influenced the maximum stress of the residual tooth tissue, with the impact of the labiolingual diameter being greater. A reduction in labiolingual diameter led to increased maximum stress throughout the tooth. The ferrule reduced the maximum stress of the core of S2 models (7.15~10.69 MPa), which is lower compared with that of S3 models (19.45~43.67 MPa).
CONCLUSIONS: The labiolingual diameter exerts a greater impact on the biomechanical characteristics of ET anterior teeth with crown restoration, surpassing the influence of the construction. The ferrule can reduce the maximum stress of the core and maintain the uniformity of stress distribution.
摘要：
目的：评估牙髓治疗（ET）前牙牙冠修复的唇舌直径和结构对咬合负荷下应力分布和生物力学安全性的影响。
方法：对全瓷冠修复的上颌中切牙建立三维有限元模型。牙齿的唇舌直径，定义为唇面和舌面突起之间的水平距离，变化如下：(D1)6.85毫米，(D2)6.35mm,和（D3）5.85毫米。模型构建如下:(S0)活髓牙；(S1)ET牙；(S2)带2mm套圈的ET牙，用纤维桩和复合树脂芯修复；(S3)无套圈的ET齿，用纤维柱和复合树脂芯修复。共开发了12个模型。总的来说,两个力载荷（100N）以与牙齿纵轴成45°斜角施加到牙冠的切缘和腭表面。分析了模型的VonMises应力分布和最大应力。
结果：无论装载位置如何，所有模型的应力集中和最大应力（34.07〜66.78MPa）发生在每个根部的唇颈1/3。唇舌直径和结构都影响残余牙齿组织的最大应力，唇舌直径的影响更大。唇舌直径的减小导致整个牙齿的最大应力增加。套圈降低了S2型芯的最大应力(7.15~10.69MPa),与S3型号(19.45~43.67MPa)相比较低。
结论：唇舌直径对内皮素前牙冠修复的生物力学特性影响较大，超越建筑的影响。套圈可以减小芯的最大应力并保持应力分布的均匀性。
方法：对全瓷冠修复的上颌中切牙建立三维有限元模型。牙齿的唇舌直径，定义为唇面和舌面突起之间的水平距离，变化如下：(D1)6.85毫米，(D2)6.35mm,和（D3）5.85毫米。模型构建如下:(S0)活髓牙；(S1)ET牙；(S2)带2mm套圈的ET牙，用纤维桩和复合树脂芯修复；(S3)无套圈的ET齿，用纤维柱和复合树脂芯修复。共开发了12个模型。总的来说,两个力载荷（100N）以与牙齿纵轴成45°斜角施加到牙冠的切缘和腭表面。分析了模型的VonMises应力分布和最大应力。
结果：无论装载位置如何，所有模型的应力集中和最大应力（34.07〜66.78MPa）发生在每个根部的唇颈1/3。唇舌直径和结构都影响残余牙齿组织的最大应力，唇舌直径的影响更大。唇舌直径的减小导致整个牙齿的最大应力增加。套圈降低了S2型芯的最大应力(7.15~10.69MPa),与S3型号(19.45~43.67MPa)相比较低。
结论：唇舌直径对内皮素前牙冠修复的生物力学特性影响较大，超越建筑的影响。套圈可以减小芯的最大应力并保持应力分布的均匀性。
