Jarman Joseph M, Hamalian Techkouhie, Randi Anthony P
Int J Oral Maxillofac Implants. 2017 September/October;32(5):992–1000. doi: 10.11607/jomi.5236. Epub 2017 Mar 15.
Aftermarket computer-aided design/computer-assisted manufacture (CAD/CAM) milled zirconia (Zr) abutments were recently introduced with minimal independent research regarding their fracture resistance. Third-party manufacturers often alter the original equipment manufacturers' (OEM) design with unknown effects on fracture resistance. These alterations include elimination of the titanium insert with subsequent introduction of Zr into the implant, changes to connection designs and shapes, and/or alterations to prosthetic screw design. This in vitro study compares the static load fracture resistance and mode of failure of alternatively engineered Zr abutments with those of prefabricated (OEM) Zr abutments with internal, external, and conical connections.
Twenty Zr stock abutments (five per group) from OEMs were selected to demonstrate fracture resistance of external hex, internal connection, and conical connection implant designs (control groups). Atlantis abutments (Dentsply) (test group) were manufactured by means of CAD/CAM to match the OEM abutments (control groups). All samples had full-coverage all-ceramic crowns luted to the abutments. Static load fracture resistance was evaluated with an Instron test device. Modes of abutment failure were evaluated using both light and scanning electron microscopy.
A Welch two-sample t test evaluated the OEM control groups vs the Atlantis test groups. Static load to failure (N) for each representative control group vs test group revealed (1) conical design OEM (387 N) vs Atlantis (211 N) (P < .011), (2) external-hex OEM (408 N) vs Atlantis (218 N) (P < .035), (3) trilobe internal connection OEM (430 N) vs Atlantis (260 N) (P < .014), and (4) internal connection OEM (448 N) vs Atlantis (244 N) (P < .02).
Atlantis CAD/CAM Zr abutments demonstrated static fracture loads lower than those of their OEM counterparts. Failure modes were Zr fractures in the conical and external hex groups. The internal connection groups demonstrated a mixed mode of failure, with screw head fracture 100% of the failures in the internal Zr connection group. The trilobe internal connection group exhibited screw-head fracture in two of five samples and Zr fracture in the remaining three samples. Clinicians should consider avoiding the alternatively engineered Atlantis Zr abutment for restoration of posterior single teeth in cases in which occlusal forces may exceed 350 to 400 N.
售后市场的计算机辅助设计/计算机辅助制造（CAD/CAM）铣削氧化锆（Zr）基台最近被引入，但关于其抗断裂性的独立研究极少。第三方制造商常常改变原始设备制造商（OEM）的设计，而这对其抗断裂性的影响未知。这些改变包括去除钛植入物并随后将Zr引入种植体、改变连接设计和形状，以及/或者改变修复螺钉设计。这项体外研究比较了经过改造的Zr基台与预制（OEM）的具有内部、外部和锥形连接的Zr基台在静态载荷下的抗断裂性和失效模式。
从OEM厂商处选取20个Zr库存基台（每组5个），以展示外部六角形、内部连接和锥形连接种植体设计的抗断裂性（对照组）。通过CAD/CAM制造Atlantis基台（登士柏公司）（试验组），使其与OEM基台（对照组）相匹配。所有样本都在基台上粘结了全覆盖式全瓷冠。使用Instron测试设备评估静态载荷下的抗断裂性。使用光学显微镜和扫描电子显微镜评估基台的失效模式。
采用韦尔奇两样本t检验评估OEM对照组与Atlantis试验组。每个代表性对照组与试验组的静态破坏载荷（N）显示：（1）锥形设计的OEM基台（387 N）与Atlantis基台（211 N）（P <.011），（2）外部六角形OEM基台（408 N）与Atlantis基台（218 N）（P <.035），（3）三叶形内部连接OEM基台（430 N）与Atlantis基台（260 N）（P <.014），以及（4）内部连接OEM基台（448 N）与Atlantis基台（244 N）（P <.02）。
Atlantis CAD/CAM Zr基台的静态断裂载荷低于其OEM对应基台。锥形和外部六角形组的失效模式为Zr断裂。内部连接组表现出混合失效模式，内部Zr连接组100%的失效为螺钉头断裂。三叶形内部连接组在5个样本中有2个出现螺钉头断裂，其余3个样本出现Zr断裂。在咬合力量可能超过350至400 N的情况下，临床医生应考虑避免使用经过改造的Atlantis Zr基台来修复后牙单颗牙。
