Akkoyun E-F, Pergel T
Bezmialem Vakif University Faculty of Dentistry Department of Oral and Maxillofacial Surgery Fatih, Istanbul, Turkey
Med Oral Patol Oral Cir Bucal. 2025 Jul 1;30(4):e528-e535. doi: 10.4317/medoral.27065.
T-shaped genioplasty is a versatile surgical technique used to correct chin deformities by altering its vertical, transverse, and sagittal dimensions. Despite numerous advancements in patient-specific implants (PSIs), the biomechanical impact of PSI thickness and the number of screws used for fixation remain unexplored. This study aims to evaluate the effects of PSI thickness and screw configurations on fixation stability in T-shaped genioplasty using finite element analysis.
Mandibular computed tomography data were used to construct 12 three-dimensional models with varying PSI thicknesses (0.6 mm, 0.9 mm, and 1.2 mm) and screw configurations (five, six, seven, and eight screws). T-shaped osteotomies were applied to create narrowing and widening genioplasty models, with iliac bone grafts placed in widening scenarios. Horizontal forces of 50 N were applied bilaterally, and fixation stability was evaluated using von Mises stress and bone displacement. Fixation was considered stable when bone displacement amounts were below 1 mm.
In narrowing models, fixation stability was achieved with five screws and a 1.2 mm PSI or seven screws with a 0.9 mm or 1.2 mm PSI, showing stress values within titanium's yield strength limits. For widening models, stable fixation was achieved with six screws and a 0.9 mm or 1.2 mm PSI, or eight screws across all tested thicknesses. Bone displacement was minimal with thicker PSIs and higher screw counts, demonstrating improved stability.
This study highlights the importance of PSI customization in optimizing fixation stability in T-shaped genioplasty. A minimum of five screws with a 1.2 mm plate or seven screws with a 0.9 mm plate is suggested for narrowing, while six screws with a 0.9 mm plate or eight screws with any tested thickness are sufficient for widening. Future research should address combined movements, dynamic loading, and long-term outcomes to refine PSI fixation strategies further.
T 形颏成形术是一种多功能外科技术，通过改变颏部的垂直、横向和矢状径来矫正颏部畸形。尽管定制患者植入物（PSI）有了诸多进展，但 PSI 厚度和用于固定的螺钉数量的生物力学影响仍未得到探索。本研究旨在使用有限元分析评估 PSI 厚度和螺钉配置对 T 形颏成形术中固定稳定性的影响。
使用下颌骨计算机断层扫描数据构建 12 个三维模型，这些模型具有不同的 PSI 厚度（0.6 毫米、0.9 毫米和 1.2 毫米）和螺钉配置（5 颗、6 颗、7 颗和 8 颗螺钉）。应用 T 形截骨术创建缩窄和加宽的颏成形术模型，在加宽情况下放置髂骨移植。双侧施加 50 N 的水平力，并使用冯·米塞斯应力和骨位移评估固定稳定性。当骨位移量低于 1 毫米时，固定被认为是稳定的。
在缩窄模型中，使用 5 颗螺钉和 1.2 毫米的 PSI 或 7 颗螺钉与 0.9 毫米或 1.2 毫米的 PSI 可实现固定稳定性，应力值在钛的屈服强度极限范围内。对于加宽模型，使用 6 颗螺钉和 0.9 毫米或 1.2 毫米的 PSI，或在所有测试厚度下使用 8 颗螺钉可实现稳定固定。较厚的 PSI 和较高的螺钉数量时骨位移最小，表明稳定性得到改善。
本研究强调了 PSI 定制在优化 T 形颏成形术中固定稳定性方面的重要性。对于缩窄，建议使用至少 5 颗螺钉和 1.2 毫米的钢板或 7 颗螺钉和 0.9 毫米的钢板，而对于加宽，6 颗螺钉和 0.9 毫米的钢板或 8 颗任何测试厚度的螺钉就足够了。未来的研究应解决联合运动、动态载荷和长期结果，以进一步完善 PSI 固定策略。
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