Effect of fiber patterns on the fracture of implant/cement interfaces

Electrospinning is a process by which fibers with micron to nanometer diameters can be obtained from an electrostatically driven jet of polymer solution. These fibers have a high surface area to volume ratio, which have numerous applications in biomedical implants such as total hip implant, dental implant. The present study is based on the hypothesis that the differences of the surface properties at titanium/cement interface due to incorporation of micro and sub-micron diameters fiber directions may have influence on the quality of titanium/cement union. The objectives of this research were to design and construct electrospinning unit for the fabrication uni-and bi-directions polycaprolactone (PCL) fiber on titanium and to measure the effect of fiber directions on the interface fracture strengths of sandwiched titanium (Ti) and poly methyl methacrylate (PMMA) cement samples with (uni-and bi-directions) and without fibers. Two groups of single edge sandwiched Ti/PMMA specimens were prepared. First group of specimen consists of Ti/PMMA sandwiched specimen without PCL fiber. Second group of specimen consists of Ti/PMMA sandwiched specimen with uni-and bi-direction PCL fibers. PCL fibers were ejected from the syringe via charged needle and deposited on two different grounded collectors to coat uni-and bi-directions PCL fibers on Ti plates. PMMA cement was poured and cured on the Ti plates with and without PCL fibers in a custom made mold to prepare Ti/PMMA samples with uni-and bi-directions fibers. Shear tests were conducted on each group of Ti/PMMA samples using Evex tensile test stage. Interface fracture toughness was calculated to determine the effect of fiber patterns on Ti/PMMA samples. This study successfully produced an electrospun unit that can produce uni-and bi-direction PCL fibers. Diameters of produced fibers were found to be in the range of 919 nm ~1.25 μm. This study found that the values of KIC of Ti/PMMA with uni-direction fiber were significantly higher when compared to the values of KIC of the Ti/PMMA without fiber (p<0.05), although the values of KIC of Ti/PMMA with bi-direction fiber were significantly lower when compared to the values of KIC of the Ti/PMMA without fiber. Results indicated that the addition of the fiber to Ti improved the quality of Ti/PMMA union and fiber directions have significant effect on the strength of the Ti-PMMA union.