Objective

To compare mechanical performance and enamel-crack propensity of direct, semi-direct, and CAD/CAM approaches for large MOD composite-resin restorations.

Methods

45 extracted maxillary molars underwent standardized slot-type preparation (5-mm depth and bucco-palatal width) including immediate dentin sealing (Optibond FL) for the inlays (30 teeth). Short-fiber reinforced composite-resin (EverX Posterior covered by Gradia Direct Posterior) was used for the direct approach, Gradia Direct Posterior for the semi-direct, and Cerasmart composite resin blocks for CAD/CAM inlays. All inlays were adhesively luted with light-curing composite-resin (preheated Gradia Direct Posterior). Shrinkage-induced enamel cracks were tracked by transillumination photography. Cyclic axial isometric chewing (5-Hz) was simulated, starting with a load of 200 N (5000 cycles), followed by stages of 400, 600, 800, 1000, 1200, and 1400 N (maximum 30,000 cycles each) until fracture or to a maximum of 185,000 cycles. Survived specimens were subjected to cyclic-load-to-failure test at 30-degree angle on the palatal cusp.

Results

Only small shrinkage-induced cracks were found in 47% of the direct restorations compared to 7% and 13% of semi-direct and CAD/CAM inlays, respectively. Survival to accelerated fatigue was similar for all three groups (Kaplan–Meier p > .05) and ranged between 87% (direct) and 93% (semi-direct and CAD/CAM). Cyclic-load-to-failure tests did not yield significant differences either (Life Table analysis, p > .05) with median values of 1675 N for CAD/CAM inlays, 1775 N for fiber-reinforced direct restorations and 1900 N for semi-direct inlays.

Significance

All three restorative techniques yielded excellent mechanical performance above physiological masticatory loads. Direct restorations performed as good as inlays when a short-fiber reinforced composite-resin base was used.

中文翻译：

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大型MOD修复体的优化：复合树脂嵌体与短纤维增强的直接修复体

客观的

比较大型MOD复合树脂修复体的直接，半直接和CAD / CAM方法的机械性能和搪瓷裂纹倾向。

方法

45颗上颌磨牙经过标准化的槽型准备（5毫米深度和颊-宽度），包括对嵌体（30颗牙齿）的即时牙本质密封（Optibond FL）。短纤维增强复合树脂（由Gradia Direct后板覆盖的EverX后板）用于直接进路，Gradia Direct Posterior用于半直接板，而Cerasmart复合树脂块用于CAD / CAM镶嵌。所有嵌体均用光固化复合树脂（预热的Gradia Direct后板）粘合粘合。通过透照摄影跟踪由收缩引起的搪瓷裂纹。模拟了循环轴向等距咀嚼（5-Hz），从200 N的载荷（5000个循环）开始，然后是400、600、800、1000、1200和1400 N的阶段（每个最大30,000个循环），直到断裂或最多185,000个周期。

结果

在直接修复体中，只有47％的裂缝是由收缩引起的，相比之下，半直接和CAD / CAM嵌体的裂缝分别为7％和13％。这三组患者的加速疲劳存活率相似（Kaplan–Meier p  > .05），介于87％（直接）和93％（半直接和CAD / CAM）之间。循环荷载-破坏测试也没有产生显着差异（寿命表分析，p  > .05），CAD / CAM嵌体的中位数为1675 N，纤维增强直接修复的中位数为1775 N，半修复的中位数为1900N。直接镶嵌。

意义

在生理咀嚼负荷之上，所有三种修复技术均产生了出色的机械性能。当使用短纤维增强复合树脂基底时，直接修复的效果与嵌体一样好。