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

Abstract

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

CLC Number:

R782.11

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

Three-dimensional finite element analysis of the crown method for the internal friction angle of horizontally impacted mandi-bular teeth

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