Properties and composition of leukocyte- and platelet-rich fibrin (L-PRF) clots may be largely affected by centrifugation protocols (function of relative centrifugal force [RCF]), which may impact biological potential repair in bone regeneration. The present in vivo study sought to assess the effect of the RCF on the composition of L-PRF clots, as well as to compare the repair potential of L-PRF clots obtained with different RCF protocols in submandibular boney defects using PLGA scaffolds for bone regeneration. Complete blood count and volumetric evaluations were performed on L-PRF clots obtained through centrifugation for 12 min at 200, 400, and 600 RCF-clot centrifugation speeds. These evaluations were completed from blood collected immediately prior to any surgical procedures. The in vivo portion comprised of three submandibular unilateral, full thickness, osteotomies (~0.40cm³) which were created in the submandibular region of six sheep, using rotary instrumentation under continuous irrigation. Subsequently, poly(lactic-co-glycolic acid) (PLGA) scaffolds were enveloped in a L-PRF membrane from one of the three spinning speeds (n = 6/RCF) and inserted into the defect (sites were interpolated to avoid site bias). Six-weeks after surgery, the mandibles were harvested en bloc and prepared for volumetric and histomorphometric evaluations. Membranes harvested from 600 RCF produced significantly larger L-PRF clots (6.97g ± 0.95) in comparison to the lower 200 RCF (5.7g ± 0.95), with no significant differences between 600 and 400, and from 400 and 200 RCF. The three tested RCFs did not alter the platelet count of the L-PRF clot. For the in vivo component, quantitative bone regeneration analyses demonstrated significantly higher values obtained with L-PRF membranes extracted post 600 RCF (27.01 ± 8%) versus 200 RCF (17.54 ± 8%), with no significant differences regarding 400 RCF (~23 ± 8%). At the qualitative histological analyses, L-PRF membranes obtained at 600 and 400 RCFs yielded improved healing throughout the defect, where the L-PRF sourced from the lowest speed, 200 RCF, presented healing primarily at the margins along with the presence of connective tissue at the central aspect of the surgical defect. Higher 600 RCF yielded larger L-PRF clots/membranes, resulting in enhanced bone repair potential in association with PLGA scaffolds for the treatment of critical size bone defects.

中文翻译：

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相对离心力对 L-PRF 的影响：一项体内颌下骨缺损再生研究

富含白细胞和富含血小板的纤维蛋白 (L-PRF) 凝块的性质和组成可能在很大程度上受到离心方案（相对离心力 [RCF] 的函数）的影响，这可能会影响骨再生中的生物潜力修复。目前的体内研究旨在评估 RCF 对 L-PRF 凝块组成的影响，以及比较使用 PLGA 支架进行骨再生的下颌下骨缺损中不同 RCF 方案获得的 L-PRF 凝块的修复潜力. 对通过以 200、400 和 600 RCF-凝块离心速度离心 12 分钟获得的 L-PRF 凝块进行全血细胞计数和体积评估。这些评估是在任何外科手术前立即收集的血液中完成的。体内_部分包括三个下颌下单侧、全厚度、截骨术（~0.40cm ³），这些截骨术是在六只羊的下颌下区域创建的，使用旋转器械在连续灌溉下进行。随后，聚（乳酸-乙醇酸共聚物）（PLGA）支架从三种旋转速度（n = 6/RCF）中的一种被包裹在 L-PRF 膜中并插入缺陷中（插入位点以避免位点偏差）。手术后六周，下颌骨被整块采集并准备进行体积和组织形态学评估。与较低的 200 RCF  （5.7 g ± 0.95)，600 和 400 之间以及 400 和 200 RCF 之间没有显着差异。三个测试的 RCF 没有改变 L-PRF 凝块的血小板计数。对于体内成分，定量骨再生分析表明，在 600 RCF (27.01 ± 8%) 与 200 RCF (17.54 ± 8%) 后提取的 L-PRF 膜获得显着更高的值，与 400 RCF (~23 ± 8%）。在定性组织学分析中，在 600 和 400 RCF 处获得的 L-PRF 膜在整个缺损处产生了改善的愈合，其中 L-PRF 来自最低速度，200 RCF，主要在边缘愈合以及结缔组织的存在在手术缺损的中心部位。更高的 600 RCF 产生更大的 L-PRF 凝块/膜，