Private Practice, Montevarchi, Verona, Italy.
Dent Traumatol. 2012 Feb;28(1):75-80. doi: 10.1111/j.1600-9657.2011.01037.x. Epub 2011 Jul 14.
The aim of the present study was to investigate whether there is a direct correlation between the amount of residual tooth structure in a fractured maxillary incisor and the fracture resistance of composite resin restorations or porcelain veneers after cyclic loading. Sixty human-extracted maxillary central and lateral incisors were mounted in an acrylic block with the coronal aspect of the tooth protruding from the block surface. The teeth were assigned to two groups: 2-mm incisal fracture and 4-mm incisal fracture. Then, the teeth were further divided into two different restoration subgroups, porcelain laminate veneer and composite resin restoration, therefore obtaining four groups for the study (n=15). The specimens were subjected to 1000 cycles of thermocycling and were mechanically tested with a custom-designed cyclic loading apparatus for 2×106 cycles or until they failed. The specimens that survived the cyclic loading were loaded on the incisal edge along the long axis of the tooth with a flat stainless steel applicator until they fractured using a universal testing machine to measure the failure load. Two-way anova was used to assess the significance of restoration, amount of fracture, and interaction effect (α=0.05). During the cyclic loading, for the composite resin group, two specimens with 2-mm fracture and three specimens with 4-mm fracture failed. For the porcelain veneer group, two specimens with 2-mm fracture and one specimen with 4-mm fracture failed. The 2-way anova did not show statistical significance for restoration (P=0.584), amount of fracture (P=0.357), or interaction effect (P=0.212). A composite resin restoration and a porcelain veneer could perform similarly for replacing a fractured incisor edge up to 4mm. Other factors such as esthetic and/or cost would be considerations to indicate one treatment over the other.
本研究旨在探讨在上颌切牙折裂后，剩余牙体组织的量与复合树脂修复体或瓷贴面在循环加载后的抗折能力之间是否存在直接相关性。将 60 个人上颌中切牙和侧切牙从牙槽骨中拔出，然后将牙冠部分从丙烯酸块的表面突出。将牙齿分为两组：2mm 切缘折裂和 4mm 切缘折裂。然后，牙齿进一步分为两种不同的修复亚组，瓷贴面和复合树脂修复体，因此研究共分为四组（n=15）。将标本进行 1000 次热循环，并使用定制的循环加载装置进行 2×106 次循环或直至失效的机械测试。经过循环加载后，将标本沿牙长轴的切缘边缘用平不锈钢涂药器加载，直至用万能试验机加载直至断裂，以测量失效载荷。使用双向方差分析评估修复体、折裂量和相互作用效果的显著性（α=0.05）。在循环加载过程中，对于复合树脂组，有两个 2mm 折裂的标本和三个 4mm 折裂的标本失效。对于瓷贴面组，有两个 2mm 折裂的标本和一个 4mm 折裂的标本失效。双向方差分析显示修复体（P=0.584）、折裂量（P=0.357）或相互作用效果（P=0.212）均无统计学意义。复合树脂修复体和瓷贴面在修复 4mm 以内的上颌切牙折裂边缘时性能相似。美观和/或成本等其他因素将是选择一种治疗方法而不是另一种治疗方法的考虑因素。
