Finite element analysis of various root shield thicknesses in maxillary central incisor socket-shield technique

doi:10.12307/2025.258

Abstract

Abstract: BACKGROUND: Socket-shield technique can effectively maintain labial soft and hard tissues, but the incidence of postoperative complications such as exposure and displacement of root shield is relatively high. It is speculated that the root shield may be exposed and displaced due to excessive load after long-term function of dental implants.
OBJECTIVE: Through three-dimensional finite element analysis, we aim to study the influence of varying root shield thicknesses on the stress distribution, equivalent stress peaks, and displacement in the root shield, periodontal ligaments, implant, and surrounding alveolar bone under normal occlusal loading. We also attempt to analyze the correlation between the thickness of the root shield and occurrence of mechanical events such as root shield exposure, displacement, and fracture.
METHODS: Cone-beam CT data of a patient who met the indication standard of socket-shield technique for maxillary central incisor were retrieved from database. Reverse engineering techniques were used to build models of the maxillary bone and root shield, while forward engineering was used to create models for the implant components based on their parameters. Models depicting various root shield thicknesses (0.5, 1.0, 1.5, and 2.0 mm) were created using Solidworks 2022 software. ANSYS Workbench 2021 software was then used to simulate and analyze the effects of varying root shield thicknesses on stress distribution, equivalent stress peaks, and displacement of the root shields, periodontal ligaments, implants, and surrounding alveolar bone under normal occlusion.
RESULTS AND CONCLUSION: (1) In all root shield models, the stress was concentrated on the palatal cervical side, both sides of the edges and the lower edge of the labial side. As the thickness of the root shield increased, the equivalent stress peak and displacement showed a decreasing trend. The 0.5 mm thickness model produced a stress concentration of 176.20 Mpa, which exceeded the yield strength (150 Mpa) of tooth tissue. (2) The periodontal ligament stress in each group was concentrated in the neck margin and upper region. With the increase of root shield thickness, the equivalent stress peak and displacement of periodontal ligament showed a decreasing trend. (3) Implant stress in all models was concentrated in the neck of the implant and the joint of the implant-repair abutment, and the labial side was more concentrated than the palatal side. With the increase of root shield thickness, the equivalent stress peak of the implant in the model showed an increasing trend. (4) In each group of models, stress of cortical bone concentrated around the neck of the implant and the periphery of the root shield, and the labial side was more concentrated than the palatal side. With the increase of the thickness of the root shield, the equivalent stress peak around the root shield decreased; the peak value of the equivalent stress of the bone around the neck of the implant showed an increasing trend. In the model, the stress of cancellous bone was mainly concentrated around the neck of the lip of the implant, the top of the thread, the root tip and the lower margin of the root shield, and the labial side was more concentrated than the palatal side. With the increase of the thickness of the root shield, the peak value of the equivalent stress of the bone around the root shield in the model showed a decreasing trend. The minimum principal stress of cortical bone in each group of models was concentrated around the neck of the implant, exhibiting a fan-shaped distribution. As the thickness of the root shield increased, the minimum principal stress of cortical bone showed an increasing trend. (5) These results indicate that different thicknesses of the root shield have different biomechanical effects. The root shield with a thickness of 0.5 mm is easy to fracture. For patients with sufficient bone width, the root shield with a thickness of 2.0 mm is an option to reduce the risk of complications such as root shield exposure, fracture, and displacement. Meanwhile, it should be taken into account to protect the periodontal ligament in the preparation process, and rounding treatments ought to be carried out on both sides and the lower edge of the root shield.

Key words: oral implantation, socket-shield technique, root shield thickness, biomechanics, complication, three-dimensional finite element

CLC Number:

Chen Guangneng, Luo Siyang, Wang Mei, Ye Bin, Chen Jiawen, Liu Yin, Zuo Yuwen, He Xianyu, Shen Jiajin, Ma Minxian. Finite element analysis of various root shield thicknesses in maxillary central incisor socket-shield technique[J]. Chinese Journal of Tissue Engineering Research, 2025, 29(10): 2052-2060.

Figures/Tables 8

References

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