Magne Pascal, Silva Silvana, Andrada Mauro de, Maia Hamilton
Int J Esthet Dent. 2016 Spring;11(1):82-97.
To assess the influence of conventional glass ionomer cement (GIC) vs resin-modified GIC (RMGIC) as a base material for novel, super-closed sandwich restorations (SCSR) and its effect on shrinkage-induced crack propensity and in vitro accelerated fatigue resistance.
A standardized MOD slottype tooth preparation was applied to 30 extracted maxillary molars (5 mm depth/5 mm buccolingual width). A modified sandwich restoration was used, in which the enamel/dentin bonding agent was applied first (Optibond FL, Kerr), followed by a Ketac Molar (3M ESPE)(group KM, n = 15) or Fuji II LC (GC) (group FJ, n = 15) base, leaving 2 mm for composite resin material (Miris 2, Coltène-Whaledent). Shrinkageinduced enamel cracks were tracked with photography and transillumination. Samples were loaded until fracture or to a maximum of 185,000 cycles under isometric chewing (5 H z), starting with a load of 200 N (5,000 X), followed by stages of 400, 600, 800, 1,000, 1,200, and 1,400 N at a maximum of 30,000 X each. Groups were compared using the life table survival analysis (α = .008, Bonferroni method).
Group FJ showed the highest survival rate (40% intact specimens) but did not differ from group KM (20%) or traditional direct restorations (13%, previous data). SCSR generated less shrinkage-induced cracks. Most failures were re-restorable (above the cementoenamel junction [CEJ]).
Inclusion of GIC/RMGIC bases under large direct SCSRs does not affect their fatigue strength but tends to decrease the shrinkage-induced crack propensity.
The use of GIC/ RMGIC bases and the SCSR is an easy way to minimize polymerization shrinkage stress in large MOD defects without weakening the restoration.
评估传统玻璃离子水门汀（GIC）与树脂改性玻璃离子水门汀（RMGIC）作为新型超封闭三明治修复体（SCSR）的基底材料的影响，及其对收缩诱导裂纹倾向和体外加速疲劳抗性的作用。
对30颗拔除的上颌磨牙进行标准化的MOD槽型牙体预备（深度5mm/颊舌径5mm）。采用改良的三明治修复体，先应用釉质/牙本质粘结剂（Optibond FL， Kerr公司），然后分别使用Ketac Molar（3M ESPE公司）（KM组，n = 15）或Fuji II LC（GC公司）（FJ组，n = 15）作为基底，预留2mm用于复合树脂材料（Miris 2，Coltène-Whaledent公司）。通过摄影和透照追踪收缩诱导的釉质裂纹。样品加载直至断裂或在等长咀嚼（5Hz）下最多循环185,000次，起始载荷为200N（5,000X），随后依次为400、600、800、1,000、1,200和1,400N，每组最多30,000次。采用寿命表生存分析比较各组（α = .008，Bonferroni法）。
FJ组显示出最高的生存率（40%完整标本），但与KM组（20%）或传统直接修复体（13%，先前数据）无差异。SCSR产生的收缩诱导裂纹较少。大多数失败病例可再次修复（在釉牙骨质界[CEJ]上方）。
在大型直接SCSR下使用GIC/RMGIC基底不影响其疲劳强度，但倾向于降低收缩诱导裂纹倾向。
使用GIC/RMGIC基底和SCSR是一种在不削弱修复体的情况下，将大型MOD缺损中聚合收缩应力降至最低的简便方法。
