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Background
Flowable resin composites (FRC) are tooth-colored restorative materials that contain a lower filler particle content, and lower viscosity than their bulk counterparts, making them useful for specific clinical applications. Yet, their chemical makeup may impact the cellular population of the tooth pulp. This in-vitro study assessed the cytocompatibility and odontogenic differentiation capacity of dental pulp stem cells (DPSCs) in response to two recent FRC material extracts.
Methods
Extracts of the FRC Aura easyflow (AEF) and Polofil NHT Flow (PNF) were applied to DPSCs isolated from extracted human teeth. Cell viability of DPSCs was assessed using MTT assay on days 1, 3 and 7. Cell migration was assessed using the wound healing assay. DPSCs’ capacity for osteo/odontogenic differentiation was assessed by measuring the degree of mineralization by Alizarin Red S staining, alkaline phosphatase enzyme (ALP) activity, and monitoring the expression of osteoprotegerin (OPG), RUNX Family Transcription Factor 2 (RUNX2), and the odontogenic marker dentin sialophosphoprotein (DSPP) by RT-PCR. Monomer release from the FRC was also assessed by High-performance liquid chromatography analysis (HPLC).
Results
DPSCs exposed to PNF extracts showed significantly higher cell viability, faster wound closure, and superior odontogenic differentiation. This was apparent through Alizarin Red staining of calcified nodules, elevated alkaline phosphatase activity, and increased expression of osteo/odontogenic markers. Moreover, HPLC analysis revealed a higher release of TEDGMA, UDMA, and BISGMA from AEF.
Conclusions
PNF showed better cytocompatibility and enhancement of odontogenic differentiation than AEF.

Background
流动树脂复合材料（Flowable Resin Composites, FRC）是一类牙色修复材料，相较于体相树脂复合材料，其填料颗粒含量与黏度更低，因此适用于特定临床场景。然而其化学组成可能影响牙髓细胞群。本体外研究评估了两种新型FRC提取物对牙髓干细胞（Dental Pulp Stem Cells, DPSCs）的细胞相容性及成牙本质分化能力。

Methods
将FRC材料Aura easyflow（AEF）与Polofil NHT Flow（PNF）的提取物作用于从拔除人牙中分离得到的牙髓干细胞。分别于第1、3、7天采用MTT法检测牙髓干细胞的细胞活力；采用划痕愈合实验评估细胞迁移能力。通过茜素红S染色检测矿化程度、碱性磷酸酶（Alkaline Phosphatase, ALP）活性，以及采用逆转录聚合酶链反应（Reverse Transcription-Polymerase Chain Reaction, RT-PCR）检测骨保护素（Osteoprotegerin, OPG）、RUNX家族转录因子2（RUNX Family Transcription Factor 2, RUNX2）与成牙本质标志蛋白牙本质涎磷蛋白（Dentin Sialophosphoprotein, DSPP）的表达水平，以此评估牙髓干细胞的成骨/成牙本质分化能力。同时采用高效液相色谱法（High-Performance Liquid Chromatography, HPLC）检测FRC的单体释放量。

Results
暴露于PNF提取物的牙髓干细胞表现出显著更高的细胞活力、更快的划痕愈合速度与更优异的成牙本质分化能力。这一结论可通过钙化结节的茜素红染色结果、升高的碱性磷酸酶活性以及上调的成骨/成牙本质标志物表达得到证实。此外，高效液相色谱分析结果显示，AEF释放的TEDGMA、UDMA与BISGMA含量更高。

Conclusions
相较于AEF，PNF展现出更优异的细胞相容性与更强的成牙本质分化促进效果。