Bagegni Aimen, Spies Benedikt C, Kern Matthias, Hazard Derek, Kohal Ralf
Medical Center - University of Freiburg, Center for Dental Medicine, Department of Prosthetic Dentistry, Faculty of Medicine - University of Freiburg, Hugstetter Straße 55, 79106, Freiburg, Germany.
Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University, Arnold-Heller-Straße 3, 24105, Kiel, Germany.
J Mech Behav Biomed Mater. 2021 Jan;113:104095. doi: 10.1016/j.jmbbm.2020.104095. Epub 2020 Sep 22.
Long-term edentulism associated with vertical loss of alveolar bone might lead to increased suprastructure height. This study aimed to evaluate the effect of suprastructure height on the stability of the implant-abutment connection by investigating the stability of two different two-piece titanium implants with internal hexagonal or conical connections under simulated oral loading conditions.
A total of 48 specimens were used. The specimens were divided into 2 groups according to their implant-abutment connection (group H: internal hex connection, group C: conical connection). Each group was further divided into 3 groups according to the applied suprastructure height (H1; C1: 10 mm, H2; C2: 14 mm and H3; C3: 18 mm) (n = 8). All specimens were subjected to a cyclic loading force of 98 N for 5 million simulated chewing cycles. Then, all implants that survived the chewing simulation were quasi-statically loaded until failure. The monotonic-failure load and monotonic-bending moment at failure were evaluated.
After the dynamic chewing loading, the implants showed the following survival rates: group H: 95.8%; group C: 100%. The implant suprastructures revealed survival rates of 100% and 91.5% for groups H and C, respectively. After the artificial chewing simulation of 5 million cycles, some implants in the groups with higher crowns (14 mm and 18 mm) showed crack formation and plastic deformations under the light microscope. Regarding monotonic-failure load, implants with shorter suprastructures (10 mm) revealed higher resistance to failure (C1: 1496 and H1: 1201 N) than longer suprastructures (18 mm) (C3: 465 and H3: 585 N) which was expected. The mean monotonic-bending moment values at failure ranged from 400.7 Ncm to 673.3 Ncm.
Implant-supported restorations with increased crown height are considered stable for an extended time period (5 million cycles which equals approximately 20 years clinical service) and a reliable treatment option in case of increased inter-arch distance. There was no difference in stability of the two internal connections. Nevertheless, the integrity of implant components might be impaired when crowns with increased heights are applied.
长期无牙合伴牙槽骨垂直吸收可能导致上部结构高度增加。本研究旨在通过研究两种不同的两件式钛种植体（内部为六边形连接或锥形连接）在模拟口腔加载条件下的稳定性，评估上部结构高度对种植体-基台连接稳定性的影响。
共使用48个标本。根据种植体-基台连接方式将标本分为2组（H组：内部六边形连接，C组：锥形连接）。每组再根据上部结构高度分为3组（H1；C1：10mm，H2；C2：14mm和H3；C3：18mm）（n = 8）。所有标本均承受98N的循环加载力，进行500万次模拟咀嚼循环。然后，所有在咀嚼模拟中存活的种植体进行准静态加载直至失效。评估单调失效载荷和失效时的单调弯矩。
动态咀嚼加载后，种植体的存活率如下：H组：95.8%；C组：100%。种植体上部结构的存活率在H组和C组分别为100%和91.5%。在500万次人工咀嚼模拟后，一些高冠（14mm和18mm）组的种植体在光学显微镜下出现裂纹形成和塑性变形。关于单调失效载荷，上部结构较短（10mm）的种植体显示出比上部结构较长（18mm）的种植体更高的抗失效能力（C1：1496和H1：1201N）（C3：465和H3：585N），这是预期的。失效时的平均单调弯矩值范围为400.7Ncm至673.3Ncm。
冠高度增加的种植体支持修复体在较长时间内（500万次循环，约等于20年临床使用）被认为是稳定的，并且在牙弓间距离增加的情况下是一种可靠的治疗选择。两种内部连接的稳定性没有差异。然而，应用高冠时种植体部件的完整性可能会受损。
