Ryou Heonjune, Turco Gianluca, Breschi Lorenzo, Tay Franklin R, Pashley David H, Arola Dwayne
Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore, MD, USA.
Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Trieste, Italy.
Dent Mater. 2016 Feb;32(2):161-70. doi: 10.1016/j.dental.2015.11.029. Epub 2015 Dec 30.
Resin bonding to dentin requires the use of self-etching primers or acid etching to decalcify the surface and expose a layer of collagen fibrils of the dentin matrix. Acid-etching reduces the stiffness of demineralized dentin from approximately 19 GPa-1 MPa, requiring that it floats in water to prevent it from collapsing during bonding procedures. Several publications show that crosslinking agents like gluteraladehyde, carbodiimide or grape seed extract can stiffen collagen and improve resin-dentin bond strength.
The objective was to assess a new approach for evaluating the changes in stiffness of decalcified dentin by polar solvents and a collagen cross-linker.
Fully demineralized dentin beams and sections of etched coronal dentin were subjected to indentation loading using a cylindrical flat indenter in water, and after treatment with ethanol or ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). The stiffness was measured as a function of strain and as a function of loading rate from 1 to 50 μm/s.
At a strain of 0.25% the elastic modulus of the fully demineralized dentin was approximately 0.20 MPa. It increased to over 0.90 MPa at strains of 1%. Exposure to ethanol caused an increase in elastic modulus of up to four times. Increasing the loading rate from 1 to 50 μm/s caused an increase in the apparent modulus of up to three times in both water and ethanol. EDC treatment caused increases in the stiffness in fully demineralized samples and in acid-etched demineralized dentin surfaces in situ.
Changes in the mechanical behavior of demineralized collagen matrices can be measured effectively under hydration via indentation with cylindrical flat indenters. This approach can be used for quantifying the effects of bonding treatments on the properties of decalcified dentin after acid etching, as well as to follow the loss of stiffness over time due to enzymatic degradation.
树脂与牙本质的粘结需要使用自酸蚀底漆或酸蚀来使表面脱钙，并暴露牙本质基质的一层胶原纤维。酸蚀会使脱矿牙本质的硬度从约19吉帕降低到1兆帕，要求其漂浮在水中以防止在粘结过程中塌陷。一些出版物表明，诸如戊二醛、碳二亚胺或葡萄籽提取物等交联剂可以使胶原变硬并提高树脂与牙本质的粘结强度。
目的是评估一种通过极性溶剂和胶原交联剂评估脱钙牙本质硬度变化的新方法。
使用圆柱形平底压头在水中对完全脱矿的牙本质梁和酸蚀的冠部牙本质切片进行压痕加载，并在用乙醇或3-(3-二甲基氨基丙基)碳二亚胺（EDC）处理后进行。测量硬度随应变以及加载速率从1至50微米/秒的函数变化。
在应变0.25%时，完全脱矿牙本质的弹性模量约为0.20兆帕。在应变1%时增加到超过0.90兆帕。暴露于乙醇会使弹性模量增加高达四倍。将加载速率从1微米/秒增加到50微米/秒会使在水和乙醇中的表观模量增加高达三倍。EDC处理使完全脱矿样品和原位酸蚀脱矿牙本质表面的硬度增加。
脱矿胶原基质的力学行为变化可以在水合状态下通过使用圆柱形平底压头进行压痕有效测量。这种方法可用于量化粘结处理对酸蚀后脱钙牙本质性能的影响，以及跟踪由于酶降解导致的硬度随时间的损失。
