Remineralization potential of fully demineralized dentin infiltrated with silica and hydroxyapatite nanoparticles

Objective

This study investigates the potential of a novel guided tissue regeneration strategy, using fully demineralized dentin infiltrated with silica and hydroxyapatite (HA) nanoparticles (NPs), to remineralize dentin collagen that is completely devoid of native hydroxyapatite.

Methods

Dentin blocks were fully demineralized with 4 N formic acid and subsequently infiltrated with silica and HA NPs. The remineralizing potential of infiltrated dentin was assessed following a twelve week exposure to an artificial saliva solution by means of TEM, EDS and micro-CT. Measurements were taken at baseline and repeated at regular intervals for the duration of the study to quantify the P and Ca levels, the mineral volume percentage and mineral separation of the infiltrated dentin specimens compared to sound dentin and non-infiltrated controls.

Results

Infiltration of demineralized dentin with nano-HA restored up to 55% of the P and Ca levels at baseline. A local increase in the concentration of calcium phosphate compounds over a period of twelve weeks resulted in a higher concentration in P and Ca levels within the infiltrated specimens when compared to the non-infiltrated controls. Remineralization of demineralized dentin with silica NPs by immersion in artificial saliva was the most effective strategy, restoring 20% of the P levels of sound dentin. Micro-CT data showed a 16% recovery of the mineral volume in dentin infiltrated with silica NPs and a significant decrease in the mineral separation to levels comparable to sound dentin.

Significance

Demineralized dentin infiltrated with silica NPs appears to encourage heterogeneous mineralization of the dentin collagen matrix following exposure to an artificial saliva solution.     

组织工程牙周膜细胞片的体内实验研究

目的:探索一种形成组织工程牙周膜的新方法并建立动物模型,为牙周组织工程奠定基础。方法:原代分离培养人牙周膜细胞,部分细胞复合明胶海绵设为对照组;另一部分细胞经特殊条件连续培养成细胞膜片设为实验组。2组实验结果择优复合支架材料后植入裸鼠皮下,4周后取材行组织病理检测。结果:经特殊条件连续培养的牙周膜细胞层叠交错相连形成具有良好的机械加工性能的生物膜片,该膜片经裸鼠体内培养形成牙周膜样组织,并在近羟基磷灰石支架侧有矿化的牙骨质样结构生成。结论:该方法制备的牙周膜细胞片在牙周组织工程具有良好的应用前景。     

纳米羟基磷灰石牙膏对人工龋再矿化研究

目的:用正畸拔除前磨牙形成早期人工龋,再使用含纳米羟基磷灰石(NanoHA)牙膏和空白牙膏分别进行再矿化实验。方法:然后利用显微镜、显微硬度计、扫描电子显微镜等检测手段检测矿化效果。结果表明:含纳米羟基磷灰石牙膏可提高釉质的抗龋力,并能使脱矿的牙釉质再矿化。     

纳米羟基磷灰石/混旋聚乳酸修复牙槽突裂的实验研究

目的:研究纳米羟基磷灰石/混旋聚乳酸(nano-HA/PDLLA)复合材料修复牙槽突裂的愈合过程。方法:将40只雄性日本大白兔随机平均分成nano-HA/PDLLA和nano-HA两组。每只动物的两侧下颌骨均外科形成类似牙槽突裂样缺损。2个月后各组动物分别以上述两种材料充填修复牙槽突裂,于2周、4周、8周、12周和24周处死动物,采用组织学、组织形态学等方法观察样本。结果:所有动物均无围术期并发症发生。术后8周内nano-HA/PDLLA组的成骨活性明显低于对照组,而在12周后两组间无明显差异。术后第12周,两组材料均基本吸收。术后第24周,nano-HA/PDLLA组和对照组新骨平均丧失高度分别为修复高度的32.1%和12.4%。结论:nano-HA是牙槽突裂修复的良好生物材料,nano-HA/PDLLA由于其对新骨形成的抑制作用和新骨吸收比例较高,需作进一步研究。     

不同浓度ICA-nHA/PLGA复合支架对兔骨髓间充质干细胞增殖、分化的影响

目的探讨不同浓度的淫羊藿苷(ICA)-纳米羟基磷灰石/聚乳酸(nHA/PLGA)复合支架对于兔骨髓间充质干细胞(rBMSC)增殖、分化的影响。方法比较0、0.1、1、10μMol/L ICA-nHA/PLGA复合支架干预24 h、72、120 h后450 nm下的吸光度,比较等体积培养基、等体积药物溶剂、1μMol/L、10μMol/L的ICA-nHA/PLGA复合支架干预24 h后高碱性磷酸酶(ALP)、骨形态发生蛋白-1(BMP-1)水平。结果干预24 h后,0.1与1μMol/L浓度下ICA-nHA/PLGA复合支架吸光度未见明显差异,而10μMol/L浓度下吸光度显著增多(P<0.05)。随着干预时间的延长,0.1、1、10μMol/L浓度下均有促进r BMSC增殖的能力,且呈浓度依赖。干预24 h后1μMol/L与10μMol/L的ICA-nHA/PLGA复合支架可明显促进ALP和BMP-1的表达(P<0.05)。结论ICA-nHA/PLGA复合支架可以显著促进rBMSC增殖与分化。