Objectives

The objectives of this study were to compare the in vitro, laboratory aging, fracture strength, failure mode and reparability of molars restored with lithium disilicate inlays and overlays in conjunction with or without immediate dentin sealing (IDS).

Methods

Forty extracted, sound human molars were selected and divided into four groups: 1) Inlays with IDS; 2) Inlays without IDS; 3) Overlays with IDS; 4) Overlays without IDS. Standard MOD preparations were made (3 mm wide, 5 mm deep) and in groups 2 and 4, all the cusps were reduced by 2 mm. Directly following tooth preparation, IDS was applied in specimens belonging to groups 1 and 3. The indirect restorations were luted with a heated composite. The restored teeth were subsequently challenged during aging (1.2 million cycles) and thermocycling loading (8000 cycles, 5–55 degrees C). Subsequently, the fracture strength was tested by a load to failure test at 45°. A failure analysis was performed using light- and scanning electron microscopy. The results were analyzed using two-way ANOVA and a Fisher exact test.

Results

Mean fracture load + SD (N) were: Group 1 (n = 12): 1610 ± 419; Group 2 (n = 12): 1115 ± 487; Group 3 (n = 12): 2011 ± 496; Group 4 (n = 12): 1837 ± 406. Teeth restored with an onlay were stronger than those restored with an inlay restoration (p < .001). Teeth with IDS were stronger overall than those without IDS (p = .026). The interaction between preparation type and the mode of dentin conditioning had no statistically significant influence on fracture strength (p = .272). Subsequently, custom hypothesis tests showed that there was no statistically significant difference in fracture strength between inlays with IDS and overlays without IDS (p = .27). Overlays tend to fail in a more destructive, non-reparable way (p = .003).

Significance

Both variables IDS and overlay preparation improve overall fracture strength. Inlays with IDS and overlays without IDS didn't differ in fracture strength. Both inlays and overlays are strong enough to withstand physiological chewing forces.

中文翻译：

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立即进行牙本质密封对二硅酸锂嵌体和覆层的老化和断裂强度的影响。

目标

这项研究的目的是比较使用二硅酸锂镶嵌物和覆盖物结合或不结合即时牙本质密封（IDS）修复的磨牙的体外，实验室老化，断裂强度，破坏模式和可修复性。

方法

选择四十个提取出来的健全的人类臼齿，分为四组：1）具有IDS的嵌体；2）没有IDS的嵌体；3）与IDS重叠；4）没有IDS的叠加层。制备标准的MOD制剂（3毫米宽，5毫米深），在第2组和第4组中，所有牙尖减少2 mm。在牙齿准备好之后，将IDS直接应用于属于第1组和第3组的标本中。用加热的复合材料将间接修复体浸润。修复后的牙齿随后在老化（120万次循环）和热循环加载（8000次循环，5-55摄氏度）期间受到挑战。随后，通过在45°下的载荷至破坏测试来测试断裂强度。使用光学和扫描电子显微镜进行故障分析。使用双向方差分析和Fisher精确检验分析结果。

结果

平均断裂载荷+ SD（N）为：第1组（n = 12）：1610±419；第2组（n = 12）：1115±487；第3组（n = 12）：2011±496；第4组（n = 12）：1837±406。用嵌体修复的牙齿比嵌体修复的牙齿强（p <.001）。具有IDS的牙齿总体上比没有IDS的牙齿更强（p = .026）。制备类型和牙本质调节方式之间的相互作用对断裂强度没有统计学上的显着影响（p = .272）。随后，自定义假设测试表明，具有IDS的嵌体和不具有IDS的覆层之间的断裂强度在统计学上没有显着差异（p = .27）。覆盖往往会以更具破坏性，不可修复的方式失败（p = .003）。

意义

变量IDS和覆盖层准备均可提高整体断裂强度。带有IDS的嵌体和不带IDS的嵌体的断裂强度没有差异。镶嵌物和覆盖物都足够坚固以承受生理的咀嚼力。