Development of new adhesive systems based on the characteristics of primary tooth dentin

乳牙本质的物理性质明显低于恒牙本质，并且更容易受到化学物质的影响。本研究的目的是开发一种新的粘接剂系统，具有温和的酸蚀能力，充分渗透到龋患牙本质，简单，易于临床使用。材料，方法和结果：Sun-Medicals 4-Meta一步自酸蚀粘接剂AQ Bond Plus（AQBP）或Hybrid Bond（HB，新产品）应用于健康或龋患乳牙牙本质。测试1：使用纳米压痕测试仪测量树脂-牙本质界面，并计算硬度（H）和杨氏模量（Y）。试验二：用FE-SEM、SEM、TEM观察树脂-牙本质界面的超微结构。（1）只有龋坏-HB组界面牙本质的H和Y值与界面下10-70 μm处的H和Y值相比无显著性差异。（2）无论是单纯AQBP组还是单纯HB组，界面牙本质的H值均明显低于界面下10-70 μm处的H值。（3）AQBP和HB的粘附层H值和Y值分别约为正常乳牙牙本质的1/2和1/3。（4）两种胶粘剂的杂化层厚度均在1 μm左右。(5)In AQBP组和HB组牙本质均完好，均见沿着界面有银纳米渗漏。(6)In在龋齿中，在混合层中没有看到银纳米渗漏，并且许多牙本质小管填充有防止银纳米渗漏的矿物质沉积物。在两个粘接剂组中，在树脂-牙本质界面和多孔龋蚀牙本质中均观察到银纳米渗漏。这些结果可能影响树脂充填的临床预后。一步法自酸蚀胶粘剂需要进一步改进，以获得稳定的粘接力

Primary dentin has significantly lower physical properties than permanent tooth dentin, and more susceptible to chemicals. The purpose of this study was to develop a new adhesive system with mild acid-etching ability, adequate penetration into the caries-affected dentin and simple and easy to clinical use.Materials, Methods and Results :Sun-Medicals 4-META one-step self-etch adhesives AQ Bond Plus (AQBP)or Hybrid Bond (HB, new product)was applied on the sound or caries-affected primary tooth dentin.#Test 1 : resin-dentin interfaces were measured with a nano-indentation tester and the hardness (H)and Young's modulus(Y)were calculated.#Test 2 : Ultrastructures of resin-dentin interfaces were observed with FE-SEM, SEM and TEM.(1)Only in the carious-HB group, the H and Y of the interfacial dentin were not significantly lower than those obtained from 10-70 μm beneath the interface.(2)Both in the sound-AQBP and sound-HB groups, the H of the interfacial dentin was significantly lower than those obtained from 10-70 μm beneath the interface.(3)Compared with sound primary tooth dentin, the H and Y values of adhesive layer of AQBP and HB were about 1/2 and 1/3, respectively.(4)The hybrid layer of both adhesives was about 1 μm thick.(5)In the sound dentin, silver nanoleakage was observed along the interface both in the AQBP and HB groups.(6)In the carious teeth, silver nanoleakage was not seen in the hybrid layer and many of the dentinal tubules were filled with mineral deposits that prevented silver nanoleakage. However, silver deposits were seen in the underlying porous caries-affected dentin.In both adhesive groups, silver nanoleakage was observed in these resin-dentin interfaces and porous caries-affected dentin. Those results might deteriorate effect of clinical prognosis of resin restorations. Further improvements of one-step self-etch adhesives are required to obtain stable adhesion