The objectives of this in-vitro study were to investigate the influence of Deep Margin Elevation (DME) and the preparation design (cusp coverage) on the fracture strength and repairability of CAD/CAM manufactured lithium disilicate (LS₂) restorations on molars.

Sound extracted human molars (n = 60) were randomly divided into 4 groups (n = 15) (inlay without DME (InoD); inlay with DME (IWD); onlay without DME (OnoD); onlay with DME (OnWD)). All samples were aged (1.2 × 10⁶ cycles of 50N, 8000 cycles of 5–55 °C) followed by oblique static loading until fracture. Fracture strength was measured in Newton and the fracture analysis was performed using a (scanning electron) microscope. Data was statistically analyzed using two-way ANOVA and contingency tables.

DME did not affect the fracture strength of LS₂ restorations to a statistically significant level (p = .15). Onlays were stronger compared to inlays (p = .00). DME and preparation design did not interact (p = .97). However, onlays with DME were significantly stronger than inlays without DME (p = .00). More repairable fractures were observed among inlays (p = .00). Catastrophic, crown-root fractures were more prevalent in onlays (p = .00). DME did not influence repairability of fractures or fracture types to a statistically significant level (p > .05).

Within the limitations of this in-vitro study, DME did not statistical significantly affect the fracture strength, nor the fracture type or repairability of LS₂ restorations in molars. Cusp coverage did increase the fracture strength. However, oblique forces necessary to fracture both inlays and onlays, either with or without DME, by far exceeded the bite forces that can be expected under physiological clinical conditions. Hence, both inlays and onlays are likely to be fracture resistant during clinical service.

这项体外研究的目的是研究深切缘高程（DME）和制备设计（尖端覆盖）对CAD / CAM制造的二硅酸锂（LS ₂）修复体在臼齿上的断裂强度和可修复性的影响。

声音提取的人类臼齿（n = 60）随机分为4组（n = 15）（不带DME的镶嵌物（InoD）；带DME的镶嵌物（IWD）；不带DME的镶嵌物（OnoD）；带DME的镶嵌物（OnWD））。所有样品都进行了时效处理（50N的1.2×10 ⁶个循环，5–55°C的8000个循环），然后倾斜静载荷直至断裂。在牛顿中测量断裂强度，并使用（扫描电子）显微镜进行断裂分析。使用双向方差分析和列联表对数据进行统计分析。

DME并未将LS ₂修复体的断裂强度影响到统计学上的显着水平（p = .15）。嵌体比嵌体强（p = .00）。DME和制剂设计没有相互作用（p = 0.97）。但是，带有DME的嵌体比没有DME的嵌体明显更坚固（p = .00）。在嵌体中观察到更多可修复的骨折（p = .00）。灾难性的冠状根骨折在覆盖物中更为普遍（p = 0.00）。DME并未将骨折或骨折类型的可修复性影响到统计学上的显着水平（p> .05）。

在这项体外研究的限制范围内，DME并没有统计学上显着影响骨折强度，也没有显着影响臼齿中LS ₂修复体的骨折类型或可修复性。尖锐的覆盖确实增加了断裂强度。然而，无论有无DME，使嵌体和嵌体断裂所需的倾斜力远远超过了在生理临床条件下可以预期的咬合力。因此，嵌体和嵌体都可能在临床服务期间具有抗断裂性。