Magne Pascal, Knezevic Alena
Don & Sybil Harrington Foundation Chair of Esthetic Dentistry, Division of Primary Oral Health Care, School of Dentistry, University of Southern California, Los Angeles, Californa 90089-7792, USA.
Quintessence Int. 2009 Oct;40(9):729-37.
To assess the influence of restorative materials and load cusps on the fatigue resistance of endodontically treated molars.
Thirty extracted molars received root canal treatment followed by a standardized tooth preparation (3-mm cuspal reduction and immediate dentin sealing). Twenty Cerec 3 overlays (Sirona Dental Systems) were milled in the ceramic Vita MKII block (Vident; groups MKIIGL and MKIIGL-Z, oven-glazed), and 10 restorations were duplicated with a composite resin (Miris 2, Coltane/Whaledent; group M2). The fitting surfaces of the restorations were hydrofluoric acid etched (porcelain only) and silanated. Preparations were airborne-particle abraded and etched. All restorations were luted with preheated Filtek Z100 (3M ESPE) and subjected to cyclic isometric chewing (5 Hz) starting at 200 N (5,000 cycles), followed by stages of 400, 600, 800, 1,000, 1,200, and 1,400 N at a maximum of 30,000 cycles each. A stainless steel load sphere was used for groups MKIIGL and M2, while a composite resin load sphere was used in group MKIIGL-Z. All samples were loaded until fracture or to a maximum of 185,000 cycles. Groups were compared using the Kaplan-Meier survival curves (P = .05).
None of the molars restored with porcelain withstood all 185,000 loading cycles (survival = 0%). The mean fracture load for MKIIGL was 1,060 N and for MKIIGL-Z, 1,280 N. In group M2, the survival rate was 50%. The rate of fracture below the CEJ was 40%, 30%, and 20% for MKIIGL, MKIIGL-Z, and M2, respectively.
Miris 2 overlays showed higher fatigue resistance than MKII porcelain (P = .01) when loaded with a stainless steel antagonist.
评估修复材料和负荷尖牙对根管治疗后磨牙抗疲劳性的影响。
30颗拔除的磨牙接受根管治疗，随后进行标准化的牙齿预备（牙尖降低3mm并立即封闭牙本质）。在Vita MKII陶瓷块（Vident公司）中铣削出20个Cerec 3嵌体（Sirona牙科系统公司）（MKIIGL组和MKIIGL-Z组，经炉内上釉），并用复合树脂（Miris 2，Coltane/Whaledent公司；M2组）复制10个修复体。修复体的贴合面用氢氟酸蚀刻（仅针对瓷修复体）并进行硅烷化处理。对预备体进行空气颗粒研磨和蚀刻。所有修复体均用预热的Filtek Z100（3M ESPE公司）粘结，并从200N（5000次循环）开始进行循环等长咀嚼（5Hz），随后依次在400、600、800、1000、1200和1400N下进行，每组最多30000次循环。MKIIGL组和M2组使用不锈钢负荷球体，而MKIIGL-Z组使用复合树脂负荷球体。所有样本加载直至断裂或最多加载185000次循环。使用Kaplan-Meier生存曲线对各组进行比较（P = 0.05）。
用瓷修复的磨牙均未承受住全部185000次加载循环（生存率 = 0%）。MKIIGL组的平均断裂负荷为1060N，MKIIGL-Z组为1280N。M2组的生存率为50%。MKIIGL组、MKIIGL-Z组和M2组在牙骨质界下方的骨折率分别为40%、30%和20%。
当使用不锈钢对抗物加载时，Miris 2嵌体显示出比MKII瓷更高的抗疲劳性（P = 0.01）。
