下颌水平低位阻生齿内摩擦角分冠法的三维有限元分析

doi:10.13591/j.cnki.kqyx.2026.07.006

摘要/Abstract

摘要：

目的通过三维有限元分析研究下颌水平低位阻生第三磨牙分冠术中切割内摩擦角对周围组织的生物力学影响规律,建立精准分冠的量化操作标准。方法基于CBCT数据构建包含阻生牙(M3M)、邻牙(M2M)、牙周膜、皮质骨/松质骨及下牙槽神经管的三维有限元模型,分别设置四组内摩擦角(50°/60°/75°/90°)的不同参数,模拟35 N垂直载荷下的分冠过程,系统评估牙体断裂效率及邻牙、颌骨、神经管的应力/位移响应。结果基于牙釉质最大屈服强度即应力阈值,通过应力集中系数(stress concentration factor,SCF)对牙体断裂效率进行量化评估,发现60°内摩擦角组较传统90°组应力集中效应提升139.57%,断裂效率提高;50°组因应力中断导致不完全断裂。在邻牙保护方面,较传统90°组,75°与60°组使M2M牙周膜应力降低16.7%。在骨折风险评估中,50°组舌侧骨板应力接近下颌骨屈服阈值。在神经管保护中,60°组神经管应力相较于75°组及50°组为最低。结论水平低位阻生第三磨牙拔除术中,切割牙冠形成的内摩擦角(60°、75°)在便于牙冠断裂及脱位的同时,一定程度上保护了第三磨牙的周围组织。但过小的内摩擦角(50°)会导致分冠后的牙体组织分布不均匀,从而导致应力中断,降低断裂效率。通过不同内摩擦角大小下分冠对周围组织所受应力及位移变化的测定,在本实验模型理想状态下,60°及75°为最佳切割牙冠时的内摩擦角,在分冠时需要控制在该角度范围内。在手术过程中应格外加强对舌侧骨板的保护措施,以有效避免对血管及神经造成损伤。

关键词: 下颌阻生第三磨牙, 微创拔牙, 三维有限元分析, 生物力学分析, 内摩擦角, 应力分布

Abstract:

Objective To investigate the biomechanical effects of internal friction angles during crown sectioning on surrounding tissues in horizontally low-positioned impacted third molars through three-dimensional finite element analysis, and establish quantitative operational criteria for precise crown division. Methods Utilizing CBCT data, a three-dimensional finite element model incorporating the impacted tooth (M3M), adjacent tooth (M2M), periodontal ligament, cortical/trabecular bone, and inferior alveolar nerve canal was constructed. Four experimental groups with distinct internal friction angles (50°/60°/75°/90°) were established to simulate crown sectioning under 35 N vertical loading. The tooth fracture efficiency and stress/displacement responses in adjacent teeth, jawbone, and neural structures were systematically evaluated. Results Using enamel’s maximum yield strength as the stress threshold, fracture efficiency was quantified through stress concentration factor (SCF) analysis. The 60° group demonstrated 139.57% greater stress concentration effect compared to conventional 90° group, indicating enhanced fracture efficiency. The 50° group exhibited incomplete fractures due to stress interruption. For adjacent tooth protection, the 75° and 60° groups reduced M2M periodontal ligament stress by 16.7% versus the 90° group. Fracture risk assessment revealed lingual bone plate stress in the 50° group approached mandibular yield thresholds. The 60° group showed minimal neural canal stress among tested angles. Conclusion Optimal internal friction angles (60°, 75°) during crown sectioning of horizontally impacted third molars effectively balance fracture efficiency with tissue preservation. Excessive reduction in friction angle (50°) causes uneven stress distribution and compromised fracture outcomes. Surgical protocols should emphasize lingual bone plate protection to prevent neurovascular damage.

Key words: mandibular impacted third molar, minimally invasive extraction, three-dimensional finite element analysis, biomechanical analysis, internal friction angle, stress distribution

中图分类号:

R782.11

张博锐, 马宇锋. 下颌水平低位阻生齿内摩擦角分冠法的三维有限元分析[J]. 口腔医学, 2026, 46(7): 521-530.

ZHANG Borui, MA Yufeng. Three-dimensional finite element analysis of the crown method for the internal friction angle of horizontally impacted mandi-bular teeth[J]. Stomatology, 2026, 46(7): 521-530.

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材料	弹性模量E/MPa	泊松比v
皮质骨	14 800	0.30
松质骨	1 850	0.30
牙釉质	80 000	0.33
牙本质	20 000	0.31
牙髓	2	0.45
牙周膜	68	0.45
神经管	70	0.45

周围结构	M0	M1	M2	M3
第二磨牙	0.17	0.14	0.16	0.13
第二磨牙牙周膜	0.06	0.05	0.06	0.10
下牙槽神经管	0.13	0.17	0.16	0.20