Gasparro Roberta, Renno Fabrizio, De Vita Simone, Lanzotti Antonio, Martorelli Massimo, Penta Francesco, Sammartino Gilberto, Ausiello Pietro
Department of Neuroscience, Reproductive Science and Dentistry, University of Naples Federico II, 80138 Naples, Italy.
Department of Industrial Engineering, University of Naples Federico II, 80125 Naples, Italy.
J Clin Med. 2025 Apr 7;14(7):2535. doi: 10.3390/jcm14072535.
: One of the most serious complications following implant placement in the atrophic posterior mandible is injury to the inferior alveolar nerve (IAN), which can also happen during occlusal loading of the implants. This study investigates the effects of 4 mm implant stress transmission to the inferior alveolar nerve during occlusal loading in cases of severe posterior mandibular atrophy. : The computer-aided design (CAD) model was created and modified through Direct Modeling techniques. The structure of cortical and trabecular bones was simplified, and it was modeled as a cylinder block. Finite element analysis (FEA) was carried out in 3D to investigate the pressure distribution over the IAN at different implant-to-nerve distances (1.5 mm, 0.5 mm, and 0.1 mm), and stress and strain deformations were simulated in the mandibular model. : The results of the pressure analysis on the inferior alveolar nerve indicate that the pressure distribution at different implant-to-nerve distances (1.5 mm, 0.5 mm, and 0.1 mm) is consistently below 0.026 MPa, which corresponds to the maximum pressure range that may block nerve impulses. This occurs even at the theoretical and simulated distance of 0.1 mm, suggesting that cortical bone stiffness plays a crucial role in mitigating stress at reduced implant-to-nerve proximities. : Within the limits of this study, ultra-short implants can be placed even less than 0.5 mm (up to 0.1 mm under the 3D-FEA hypothesis) above the inferior alveolar nerve under the 3D-FEA hypothesis, while maintaining pressure below the threshold value. This is due to the rigidity of the cortical bone, which helps to reduce pressure transmission to the nerve. These findings may expand the indications for ultra-short implants, even in mandibles with a residual bone height of just 4 mm.
在下颌后牙区牙槽骨萎缩的情况下植入种植体后，最严重的并发症之一是下牙槽神经（IAN）损伤，这种损伤在种植体咬合加载过程中也可能发生。本研究调查了在严重下颌后牙区牙槽骨萎缩病例的咬合加载过程中，4毫米种植体应力传递至下牙槽神经的影响。：通过直接建模技术创建并修改计算机辅助设计（CAD）模型。简化皮质骨和松质骨的结构，并将其建模为圆柱体。进行三维有限元分析（FEA），以研究在不同种植体与神经距离（1.5毫米、0.5毫米和0.1毫米）时下牙槽神经上的压力分布，并在下颌模型中模拟应力和应变变形。：下牙槽神经压力分析结果表明，在不同种植体与神经距离（1.5毫米、0.5毫米和0.1毫米）下的压力分布始终低于0.026兆帕，这对应于可能阻断神经冲动的最大压力范围。即使在理论和模拟距离为0.1毫米时也是如此，这表明皮质骨刚度在减少种植体与神经近距离时的应力方面起着关键作用。：在本研究的范围内，根据三维有限元分析假设，超短种植体可以放置在下牙槽神经上方甚至小于0.5毫米（在三维有限元分析假设下可达0.1毫米）处，同时将压力保持在阈值以下。这是由于皮质骨的刚性，有助于减少压力传递至神经。这些发现可能会扩大超短种植体的适应症，即使在剩余骨高度仅为4毫米的下颌骨中也是如此。
