Kumchai Hattanas, Juntavee Patrapan, Sun Arthur F, Nathanson Dan
Department of Restorative Sciences & Biomaterials, Goldman School of Dental Medicine, Boston University, Boston, MA 02118, USA.
Dent J (Basel). 2020 Apr 27;8(2):37. doi: 10.3390/dj8020037.
Current techniques for repairing porcelain-chipped restorations have several limitations. With advances in CAD/CAM technology, the combination of resin cements and high-strength ceramic materials might offer new options for repairing the chipping of veneering ceramic.
The purpose of this study is to compare the load-to-failure of veneered zirconia crowns repaired by different materials.
Veneered zirconia crowns were made on aluminum dies (n = 10/group). Feldspathic porcelain (Vita VM9, Vident) was applied to the zirconia coping (Vita In-Ceram YZ, Vident) in a cylindrical shape (Ø 10.5 mm, height 7.5 mm). A bevel cut on the porcelain veneer (45 degree, 3 mm width) was made at one side of each crown to simulate porcelain chipping. The crowns were then divided into four different groups according to the repair materials: 1. Conventional resin composite (A; Tetric EvoCeram, Ivoclar Vivadent); 2. Flowable resin composite (B; G-aenial Universal Flo, GC america); 3. CAD/CAM milled feldspathic ceramic (C; Vita Trilux Forte, Vident); 4. CAD/CAM milled lithium disilicate glass-ceramic (D; IPS e.max CAD, Ivoclar Vivadent). Resin cement (Multilink Automix, Ivoclar Vivadent) was used to cement the CAD/CAM ceramic materials to the beveled crowns. Each crown underwent 5000 cycles of thermocycling. The strength test was performed on an Instron universal testing machine by loading force on the center of repaired part to record load-to-failure. Data were analyzed by ANOVA and Tukey HSD post-hoc tests (α = 0.05).
Mean loads-to-failure (in Newton +/- SD) of repaired veneered zirconia crowns were: Gr. A: 660.0 ± 200.5; Gr. B: 681.7 ± 175.9; Gr. C: 1236.0 ± 188.8; Gr. D: 1536.3 ± 286.1. Catastrophic failure was the most dominant failure mode in every group. Few specimens exhibited cohesive failure. Only one specimen in group D had adhesive failure.
Within the limitation of the study, veneered zirconia crowns repaired with CAD/CAM ceramic materials have significantly higher load-to-failure than veneered crowns repaired with resin composite ( ≤ 0.05).
Traditionally, porcelain-chipped restorations are often repaired with resin composite and bonding technique. Repairing chipped porcelain with CAD/CAM ceramics fitting the fractured parts can be alternative option with potential advantages. More well-designed studies are necessary to justify this novel repair technique.
目前修复瓷崩裂修复体的技术存在若干局限性。随着CAD/CAM技术的进步，树脂粘结剂与高强度陶瓷材料的结合可能为修复饰面陶瓷的崩裂提供新的选择。
本研究的目的是比较用不同材料修复的饰面氧化锆全冠的断裂载荷。
在铝制代型上制作饰面氧化锆全冠（每组n = 10）。将长石质瓷（Vita VM9，Vident）应用于氧化锆基底冠（Vita In-Ceram YZ，Vident）上，制成圆柱形（直径10.5 mm，高7.5 mm）。在每个全冠的一侧对瓷贴面进行斜切（45度，宽3 mm）以模拟瓷崩裂。然后根据修复材料将全冠分为四组：1. 传统树脂复合材料（A组；Tetric EvoCeram，Ivoclar Vivadent）；2. 流动树脂复合材料（B组；G-aenial Universal Flo，GC america）；3. CAD/CAM铣削长石质陶瓷（C组；Vita Trilux Forte，Vident）；4. CAD/CAM铣削二硅酸锂玻璃陶瓷（D组；IPS e.max CAD，Ivoclar Vivadent）。使用树脂粘结剂（Multilink Automix，Ivoclar Vivadent）将CAD/CAM陶瓷材料粘结到斜切的全冠上。每个全冠进行5000次热循环。在Instron万能试验机上对修复部位的中心施加加载力以记录断裂载荷，进行强度测试。数据采用方差分析和Tukey HSD事后检验进行分析（α = 0.05）。
修复后的饰面氧化锆全冠的平均断裂载荷（牛顿±标准差）为：A组：660.0 ± 200.5；B组：681.7 ± 175.9；C组：1236.0 ± 188.8；D组：1536.3 ± 286.1。灾难性断裂是每组中最主要的断裂模式。很少有标本表现出内聚性断裂。D组只有一个标本出现粘结性断裂。
在本研究的局限性内，用CAD/CAM陶瓷材料修复的饰面氧化锆全冠的断裂载荷显著高于用树脂复合材料修复的饰面全冠（P≤0.05）。
传统上，瓷崩裂的修复体通常采用树脂复合材料和粘结技术进行修复。用适合断裂部位的CAD/CAM陶瓷修复崩裂的瓷体可能是一种具有潜在优势的替代选择。需要更多设计良好的研究来证明这种新型修复技术的合理性。
