Ralf Kohal^1,*; Kirstin Vach²; Julian Nold¹; Christopher von Schierholz¹

¹Department of Prosthetic Dentistry, Medical Center - University of Freiburg, Center for Dental Medicine, Faculty of Medicine, University of Freiburg; ²Faculty of Medicine and Medical Center - University of Freiburg, Institute of Medical Biometry and Statistics, Freiburg, Germany

Background: Biomechanical stability data on two-piece zirconia oral implants restored with zirconia restorations are rarely reported.

Aim/Hypothesis: The objective of this investigation was, therefore, to evaluate the long-term stability of a two-piece zirconia implant restored with a zirconia abutment.

Material and Methods: Thirty-two implants (Ø 4.0 mm; Ceralog, Altatec, Wimsheim, Germany) were embedded according to ISO 14801 and restored with zirconia abutments (DEDICAM, Camlog) (lever arm for all implants: 5.59 ± 0.03 mm). Three subgroups (n = 8) were exposed either to dynamic loading alone (group DL, 10⁷ chewing cycles; load 98 N), to hydrothermal treatment alone (group HT, aging in 85 ⁰C hot water, 10⁷ cycles, no load) or to a combination of both (group DL/HT) in a chewing simulator. One subgroup (group 0) served as untreated control group. One sample of each subgroup was evaluated for phase-transformation (not part of this abstract). The remaining samples were loaded until fracture in a universal testing machine. A one-way ANOVA was used to analyze loading/bending moment differences between treatment groups. The Student-Newman-Keuls method was applied to correct for multiple testing. A t-test was used for within-group comparisons. The probability level for statistical significance was set to p < 0.05.

Results: Three out of seven samples in the DL group and six out of seven samples in the DL/HT group fractured during artificial loading. The load to failure attributed to these implants was 98 N. The mean fracture strength for the DL group was 471 N (±354 N) and 193 N (±251 N) for the DL/HT group (Table 1). The stability test in the universal testing machine of groups 0 and HT lead either to implant or to abutment fractures. In group 0, four crowns fractured at the abutment level at a mean load of 564 N. The implants of these four samples, hence, showed no damage on a macro- and microscopic level. In the same group, three implants fractured at a mean of 673 N (implant/abutment values together: 611 N). In group HT, three abutments fractured at a mean load of 625 N, and four of the implants at 666 N (implant/abutment values together: 648 N) (Table 1).

Conclusion and Clinical implications: The fracture stability/bending moments of the not loaded implants (0 and HT) were comparable to other two-piece implants. The number of fractured implants in the artificial chewing simulator, however, was high in comparison to other studies. Within the limits of this investigation, it can be concluded that loading reduces the stability of the investigated two-piece zirconia implant and therefore its reliability.

The implants and abutments were kindly provided by CAMLOG Biotechnologies, GmbH.

Disclosure of Interest: None Declared

Keywords: biomechanical stability, implant stability, zirconia

拉尔夫·科哈尔^1,* ; 克尔斯汀·瓦赫² ; 朱利安诺德¹ ; 克里斯托弗·冯·席尔霍尔茨¹

¹修复牙科系，医学中心 - 弗莱堡大学，牙科医学中心，医学院，弗莱堡大学；²医学和医学中心 - 弗莱堡大学，医学生物计量和统计研究所，弗莱堡，德国

背景：用氧化锆修复体修复的两件式氧化锆口腔种植体的生物力学稳定性数据很少报道。

目的/假设：因此，本次调查的目的是评估用氧化锆基台修复的两件式氧化锆种植体的长期稳定性。

材料和方法： 32 个种植体（Ø 4.0 mm；Ceralog, Altatec, Wimsheim, Germany）根据 ISO 14801 埋入并用氧化锆基台（DEDICAM、Camlog）修复（所有种植体的杆臂：5.59 ± 0.03 mm）。三个亚组 ( n = 8) 单独接受动态负荷（DL 组，10 ^{7 个}咀嚼周期；负荷 98 N），单独接受水热处理（HT 组，在 85 ⁰ C 热水中老化，10 ⁷循环，无负荷）或在咀嚼模拟器中组合使用（DL/HT 组）。一个亚组（第 0 组）作为未治疗的对照组。每个亚组的一个样本进行了相变评估（不是本摘要的一部分）。其余样品在万能试验机中加载直至断裂。使用单向方差分析来分析治疗组之间的载荷/弯矩差异。应用Student-Newman-Keuls 方法对多重测试进行校正。t 检验用于组内比较。统计显着性的概率水平设置为p < 0.05。

结果：DL 组中 7 个样品中的 3 个和 DL/HT 组中 7 个样品中的 6 个在人工加载期间断裂。归因于这些种植体的失效载荷为 98 N。DL 组的平均断裂强度为 471 N (±354 N)，DL/HT 组的平均断裂强度为 193 N (±251 N)（表 1）。0 组和 HT 组万能试验机中的稳定性测试导致种植体或基台断裂。在第 0 组中，四个牙冠在基台水平以 564 N 的平均载荷断裂。因此，这四个样本的种植体在宏观和微观水平上都没有显示出损坏。在同一组中，三个种植体在平均 673 N 下断裂（种植体/基台值加起来：611 N）。在 HT 组中，三个基台在 625 N 的平均载荷下断裂，四个种植体在 666 N 下断裂（种植体/基台值加起来：648 N）（表 1）。

结论和临床意义：未加载种植体（0 和 HT）的断裂稳定性/弯曲力矩与其他两件式种植体相当。然而，与其他研究相比，人工咀嚼模拟器中断裂植入物的数量很高。在本研究的范围内，可以得出结论，负载会降低所研究的两件式氧化锆植入物的稳定性，从而降低其可靠性。

种植体和基台由 CAMLOG Biotechnologies, GmbH 友情提供。

利益披露：无申报

关键词: 生物力学稳定性, 种植体稳定性, 氧化锆