Department of Conservative Dentistry and Periodontology, University Hospital, Ludwig-Maximilians-University, Goethestrasse 70, 80336, Munich, Germany.
Biomaterials Department, Faculty of Oral and Dental Medicine, Cairo University, Cairo, Egypt.
Clin Oral Investig. 2021 Aug;25(8):4927-4940. doi: 10.1007/s00784-021-03801-2. Epub 2021 Jan 27.
This investigation evaluated the effect of flowable liners beneath a composite restoration applied via different methods on the pattern of shrinkage vectors.
Forty molars were divided into five groups (n = 8), and cylindrical cavities were prepared and bonded with a self-etch adhesive (AdheSe). Tetric EvoCeram Bulk Fill (TBF) was used as the filling material in all cavities. The flowable liners Tetric EvoFlow Bulk Fill (TEF) and SDR were used to line the cavity floor. In gp1-TBF, the flowable composite was not used. TEF was applied in a thin layer in gp2-fl/TEF + TBF and gp3-fl/TEF + TBFincremental. Two flowable composites with a layer thickness of 2 mm were compared in gp4-fl/TEF + TBF and gp5-fl/SDR + TBF. TEF and SDR were mixed with radiolucent glass beads, while air bubbles inherently present in TBF served as markers. Each material application was scanned twice by micro-computed tomography before and after light curing. Scans were subjected to image segmentation for calculation of the shrinkage vectors.
The absence of a flowable liner resulted in the greatest shrinkage vectors. A thin flowable liner (gp2-fl/TEF + TBFbulk) resulted in larger overall shrinkage vectors for the whole restoration than a thick flowable liner (gp4-fl/TEF + TBF). A thin flowable liner and incremental application (gp3-fl/TEF + TBFincremental) yielded the smallest shrinkage vectors. SDR yielded slightly smaller shrinkage vectors for the whole restoration than that observed in gp4-fl/TEF + TBF.
Thick flowable liner layers had a more pronounced stress-relieving effect than thin layers regardless of the flowable liner type.
It is recommended to apply a flowable liner (thin or thick) beneath bulk-fill composites, preferably incrementally.
本研究评估了不同方法应用于复合修复体下方的可流动衬垫对收缩矢量模式的影响。
将 40 颗磨牙分为 5 组（n=8），制备圆柱形窝洞并用自酸蚀粘结剂（AdheSe）粘结。所有窝洞均使用 Tetric EvoCeram Bulk Fill（TBF）作为填充材料。使用 Tetric EvoFlow Bulk Fill（TEF）和 SDR 作为流动衬垫覆盖窝洞底部。在 gp1-TBF 中不使用可流动复合树脂。在 gp2-fl/TEF+TBF 和 gp3-fl/TEF+TBFincremental 中，薄涂一层 TEF。在 gp4-fl/TEF+TBF 和 gp5-fl/SDR+TBF 中比较了两种层厚为 2mm 的可流动复合材料。TEF 和 SDR 与不透射线玻璃珠混合，而 TBF 中固有存在的气泡则作为标记。每种材料在光固化前后用微计算机断层扫描（micro-CT）扫描两次。对扫描结果进行图像分割，以计算收缩矢量。
无流动衬垫组的收缩矢量最大。薄的可流动衬垫（gp2-fl/TEF+TBFbulk）比厚的可流动衬垫（gp4-fl/TEF+TBF）导致整个修复体的整体收缩矢量更大。薄的可流动衬垫和增量应用（gp3-fl/TEF+TBFincremental）产生的收缩矢量最小。SDR 对整个修复体产生的收缩矢量比 gp4-fl/TEF+TBF 略小。
无论流动衬垫类型如何，厚的流动衬垫层比薄的流动衬垫层具有更显著的应力释放效果。
建议在块状填充复合材料下方应用流动衬垫（薄或厚），最好采用增量式。
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