Lohbauer Ulrich, Belli Renan, Cune Marco S, Schepke Ulf
Research Laboratory for Dental Biomaterials, Dental Clinic 1-Operative Dentistry and Periodontology, Friedrich-Alexander University Erlangen-Nuremberg (FAU), Erlangen, Germany.
Department of Fixed Prosthodontics, Center for Dentistry and Oral Hygiene, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
SAGE Open Med Case Rep. 2017 Nov 22;5:2050313X17741015. doi: 10.1177/2050313X17741015. eCollection 2017.
Today, a substantial part of the dental crown production uses computer-aided design and computer-aided manufacturing (CAD/CAM) technology. A recent step in restorative dentistry is the replacement of natural tooth structure with pre-polymerized and machined resin-based methacrylic polymers. Recently, a new CAD/CAM composite was launched for the crown indication in the load-bearing area, but the clinical reality forced the manufacturer to withdraw this specific indication. In parallel, a randomized clinical trial of CAD/CAM composite crowns luted on zirconia implant abutments revealed a high incidence of failure within the first year of service. Fractured crowns of this clinical trial were retrieved and submitted to a fractographic examination. The aim of the case series presented in this article was to identify failure reasons for a new type of CAD/CAM composite crown material (Lava Ultimate; 3M Oral Care, St. Paul, Minnesota, USA) via fractographic examinations and analytical assessment of luting surfaces and water absorption behavior. As a result, the debonding of the composite crowns from the zirconia implant abutments was identified as the central reason for failure. The adhesive interface was found the weakest link. A lack of silica at the zirconia surface certainly has compromised the bonding potential of the adhesive system from the beginning. Additionally, the hydrolytic stress released from swelling of the resin-based crown (water absorption) and transfer to the luting interface further added to the interfacial stress and most probably contributed to a great extend to the debonding failure.
如今，牙冠生产的很大一部分采用了计算机辅助设计和计算机辅助制造（CAD/CAM）技术。修复 dentistry 领域的最新进展是用预聚合和加工的树脂基甲基丙烯酸聚合物替代天然牙结构。最近，一种新型的 CAD/CAM 复合材料被推出用于承重区域的牙冠修复，但临床实际情况迫使制造商撤回了这一特定适应症。与此同时，一项关于在氧化锆种植体基台上粘结 CAD/CAM 复合牙冠的随机临床试验显示，在服役的第一年失败率很高。该临床试验中折断的牙冠被回收并进行了断口分析检查。本文所呈现的病例系列的目的是通过断口分析检查以及对粘结面和吸水行为的分析评估，确定一种新型 CAD/CAM 复合牙冠材料（Lava Ultimate；3M 口腔护理公司，美国明尼苏达州圣保罗）的失败原因。结果发现，复合牙冠与氧化锆种植体基台的脱粘是失败的主要原因。粘结界面被认为是最薄弱的环节。氧化锆表面缺乏二氧化硅从一开始就肯定损害了粘结系统的粘结潜力。此外，基于树脂的牙冠肿胀（吸水）释放出的水解应力传递到粘结界面，进一步增加了界面应力，很可能在很大程度上导致了脱粘失败。
