Department of General Practice, School of Dentistry, Virginia Commonwealth University, Richmond, Virginia, United States of America.
Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, Richmond, Virginia, United States of America.
PLoS One. 2020 Feb 24;15(2):e0229360. doi: 10.1371/journal.pone.0229360. eCollection 2020.
This study evaluated the von Mises stress (MPa) and equivalent strain occurring around monolithic yttria-zirconia (Zir) implant using three clinically simulated finite element analysis (FEA) models for a missing maxillary central incisor. Two unidentified patients' cone-beam computed tomography (CBCT) datasets with and without right maxillary central incisor were used to create the FEA models. Three different FEA models were made with bone structures that represent a healed socket (HS), reduced bone width edentulous site (RB), and immediate extraction socket with graft (EG). A one-piece abutment-implant fixture mimicking Straumann Standard Plus tissue level RN 4.1 X 11.8mm, for titanium alloy (Ti) and Zir were modeled. 178 N oblique load and 200 N vertical load were used to simulate occlusal loading. Von Mises stress and equivalent strain values for around each implant model were measured. Within the HS and RB models the labial-cervical region in the cortical bone exhibited highest stress, with Zir having statistically significant lower stress-strain means than Ti in both labial and palatal aspects. For the EG model the labial-cervical area had no statistically significant difference between Ti and Zir; however, Zir performed better than Ti against the graft. FEA models suggest that Ti, a more elastic material than Zir, contributes to the transduction of more overall forces to the socket compared to Zir. Thus, compared to Ti implants, Zir implants may be less prone to peri-implant bone overloading and subsequent bone loss in high stress areas especially in the labial-cervical region of the cortical bone. Zir implants respond to occlusal loading differently than Ti implants. Zir implants may be more favorable in non-grafted edentulous or immediate extraction with grafting.
本研究评估了单颗氧化锆（Zir）种植体周围的冯·米塞斯（von Mises）应力（MPa）和等效应变，使用三种临床模拟的有限元分析（FEA）模型来模拟上颌中切牙缺失。使用两名未识别患者的锥形束计算机断层扫描（CBCT）数据集，包括有和没有右侧上颌中切牙，来创建 FEA 模型。制作了三种不同的 FEA 模型，具有代表愈合牙槽窝（HS）、牙槽骨宽度减少的无牙部位（RB）和带植骨的即刻拔牙窝（EG）的骨结构。模拟 Straumann Standard Plus 组织水平 RN 4.1 X 11.8mm 的一体式基台-种植体修复体，由钛合金（Ti）和 Zir 制成。使用 178 N 斜向载荷和 200 N 垂直载荷模拟咬合加载。测量了每个种植体模型周围的冯·米塞斯应力和等效应变值。在 HS 和 RB 模型中，皮质骨的唇侧-颈侧区域表现出最高的应力，Zir 的唇侧和腭侧的应力-应变均值均显著低于 Ti。对于 EG 模型，Ti 和 Zir 之间的唇侧-颈侧区域没有统计学上的显著差异；然而，Zir 在对抗植骨方面的表现优于 Ti。FEA 模型表明，Ti 是一种比 Zir 更具弹性的材料，与 Zir 相比，它会将更多的整体力传递到牙槽窝。因此，与 Ti 种植体相比，Zir 种植体在上颌中切牙缺失或即刻拔牙后植骨的皮质骨唇侧-颈侧等高应力区域可能不易发生种植体周围骨过度负荷和随后的骨丢失。Zir 种植体对咬合加载的反应与 Ti 种植体不同。Zir 种植体在非植入或即刻拔牙后带植骨的情况下可能更有利。
