Jafarian Mohammad, Mirhashemi Fatemeh Sadat, Emadi Naghmeh
Department of Oral and Maxillofacial Surgery, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Research Institute for Dental Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Dent Med Probl. 2019 Jan-Mar;56(1):27-32. doi: 10.17219/dmp/102710.
The choice between reducing the bone height and inserting a shorter implant with a greater diameter or a longer and narrower implant without altering the bone height is a challenge in clinical practice.
The purpose of this finite element analysis (FEA) was to compare the pattern and level of stress around implants with different lengths and diameters and with different amounts of bone loss, which changes the implant-crown ratio over time, depending on the available bone and the treatment modality.
The FEA was carried out to evaluate the stress distribution in bone around 3.25 × 13 mm and 4 × 11 mm 3i implants, and 3.3 × 12 mm and 4.1 × 10 mm Straumann® implants. A 3D segment of the mandible was reconstructed from a computed tomography image of the posterior mandible. Occlusal force was simulated by applying 200 N vertical and 40 N horizontal loads to the occlusal node at the center of the abutment. The pattern of stress distribution in bone was evaluated in 10 models for each implant, representing 0-9 mm of bone resorption.
The results showed that along with decreasing the implant insertion depth, and consequently the implant-crown ratio, the amount of stress in bone increased. The amount of stress increased with an increase in depth of bone loss in all models, but there was no significant change in the amount of stress in the first several millimeters of bone loss.
The results suggest that in terms of stress distribution, it is better to reduce the bone height and insert shorter implants with a greater diameter than longer implants with a smaller diameter.
在临床实践中，是降低骨高度并植入直径较大的较短种植体，还是植入长度较长但直径较窄的种植体而不改变骨高度，这是一个挑战。
本有限元分析（FEA）的目的是比较不同长度和直径以及不同骨量丢失情况下种植体周围的应力模式和水平，骨量丢失会随时间改变种植体 - 牙冠比例，这取决于可用骨量和治疗方式。
进行有限元分析以评估3.25×13 mm和4×11 mm的3i种植体以及3.3×12 mm和4.1×10 mm的士卓曼种植体周围骨中的应力分布。从下颌后部的计算机断层扫描图像重建下颌骨的三维片段。通过在基台中心的咬合节点上施加200 N垂直载荷和40 N水平载荷来模拟咬合力。对每种种植体的10个模型评估骨中应力分布模式，代表0 - 9 mm的骨吸收情况。
结果表明，随着种植体植入深度的减小，进而种植体 - 牙冠比例的减小，骨中的应力量增加。在所有模型中，应力量随着骨丢失深度的增加而增加，但在骨丢失的最初几毫米内应力量没有显著变化。
结果表明，就应力分布而言，降低骨高度并植入直径较大的较短种植体比植入直径较小的较长种植体更好。
