Amid Reza, Rasoolzadeh Raheleh Akhavan, Motlagh Amir Mahmoudi, Dehnavi Farshad, Kadkhodazadeh Mahdi
Dental Research Center, Research Institute of Dental Sciences, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Department of Periodontics, Zanjan University of Medical Sciences, Zanjan, Iran.
J Long Term Eff Med Implants. 2017;27(1):1-11. doi: 10.1615/JLongTermEffMedImplants.2017019926.
Short implants can be used as alternatives to standard implants to prevent invasive surgical procedures. However, due to concerns about complications caused by less bone-implant contact area, researchers have focused on biomechanical properties of short implants and methods to promote them. Splinting has been suggested to decrease the limitation of short implants. This study compared the pattern of stress and strain distribution in bone supporting splinted standard and short implants positioned at crestal and subcrestal levels. An edentulous posterior mandible was made using computer-aided design. Five models of different combinations of splinted short (4 × 6 mm) and standard (4 × 10 mm) implants placed at the level of crestal bone or subcrestally mesial and distal to the edentulous region with a pontic between them were designed using the CATIA software program. ANSYS software was used for finite element analysis (FEA). In each model, 100 and 300 N loads at zero (parallel to the long axis of implants) and 30° angles were applied to implants. Maximum stress and strain for each of the five models, including equivalent stress, shear stress, and strain in peri-implant cortical and cancellous bone, were calculated and stress distribution pattern in different models were recorded. The highest stress was caused by the 300 N load applied at a 30° angle, followed by the 300 N load applied axially and the 100 N load applied at 30°. This order changed in model 1, where the highest stress was noted under the 300 N load at 30°, followed by the 100 N load at 30°. Maximum stress in peri-implant bone occurred under oblique (30°) load. Maximum stress was noted when two splinted short implants were placed subcrestally. In addition, stress in bone around crestal-level splinted short implants was lower than that around standard implants. Combination of short and standard implants had no biomechanical advantage. Application of load parallel to the long axis can significantly decrease stress in peri-implant bone. Although the combination of short and standard implants has no biomechanical advantage, crestal-level placement of splinted short implants is a suitable treatment plan.
短种植体可作为标准种植体的替代物，以避免侵入性手术操作。然而，由于担心骨-种植体接触面积减小会导致并发症，研究人员一直专注于短种植体的生物力学性能及其改善方法。有人提出采用夹板固定来减少短种植体的局限性。本研究比较了位于牙槽嵴顶和牙槽嵴顶以下水平的夹板固定标准种植体和短种植体在骨支持方面的应力和应变分布模式。利用计算机辅助设计制作了无牙后下颌模型。使用CATIA软件程序设计了五种模型，分别为在无牙区近中和远中牙槽嵴顶水平或牙槽嵴顶以下水平放置夹板固定的短种植体（4×6 mm）和标准种植体（4×10 mm），两者之间有桥体连接。使用ANSYS软件进行有限元分析（FEA）。在每个模型中，分别在零角度（平行于种植体长轴）和30°角对种植体施加100 N和300 N的载荷。计算五个模型中每个模型的最大应力和应变，包括等效应力、剪应力以及种植体周围皮质骨和松质骨中的应变，并记录不同模型中的应力分布模式。最大应力是由以30°角施加的300 N载荷引起的，其次是以轴向施加的300 N载荷和以30°角施加的100 N载荷。在模型1中这种顺序发生了变化，其中在30°角的300 N载荷下观察到最高应力，其次是30°角的100 N载荷。种植体周围骨中的最大应力出现在倾斜（30°）载荷下。当两个夹板固定的短种植体放置在牙槽嵴顶以下时观察到最大应力。此外，牙槽嵴顶水平夹板固定的短种植体周围骨中的应力低于标准种植体周围的应力。短种植体和标准种植体的组合没有生物力学优势。平行于种植体长轴施加载荷可显著降低种植体周围骨中的应力。虽然短种植体和标准种植体的组合没有生物力学优势，但牙槽嵴顶水平放置夹板固定的短种植体是一种合适的治疗方案。
