A Bone-Like Precoating Strategy for Implants: Collagen Immobilization and Its Mineralization on Pure Titanium Implant Surface
Many surface modification strategies are currently of interest in improving integration of implants to bone. An in vitro precoating of a bone-like mineralized layer of immobilized collagen on the implant surface is a potentially valuable approach to improve host acceptance of the implant. The goal of this investigation was to develop a method to precoat in vitro a bone-like mineralized collagen layer on a pure titanium dental implant surface. The study was conducted on acid-etched and nonetched surfaces of screw implants. Initially, a procedure was standardized to self-assemble collagen from a collagen solution. In subsequent experiments, the implant was also placed inside the solution, and after 3 days, collagen was found to be coated on the implant surface. Mineralization of the collagen gel as well as collagen coating on the implant was carried out by calcium phosphate precipitation from a mineralizing solution of calcium chloride containing polyvinyl phosphonic acid and polyaspartic acid, which served as polyanionic additives to help disperse the precipitation and template mineral nucleation. The implant was kept in the mineralizing solution and maintained for 2 weeks in an incubator at 37°C with a phosphate vapor phase generated from a vial containing dihydrogen ammonium phosphate in the incubator. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analysis confirmed the coated layer to be a biomimetic bone-like mineralized type 1 collagen. Initial studies using osteoblast-like cells indicated cellular attachment on the modified surface. The method appears to be a promising way to generate in vitro a bone-like layer on the implant surface.Abstract


Scanning electron microscopy micrographs of collagen layer and its mineralization. (a) Initial coronal surface of Steri-Oss implant as is, (b) coronal surface of Steri-Oss implant after collagen coating, (c) acid-etched (threaded region) surface of Steri-Oss implant before collagen coating, (d) acid-etched (threaded region) of Steri-Oss implant surface after collagen coating, (e) initial surface of Swede Vent implant, and (f) Swede Vent implant after deposition of immobilized collagen layer on the implant surface, before mineralization

and 6. Figure 5. Swede Vent implant surface after mineralization experiments. Figure 6. X-ray diffraction patterns of Swede Vent implant before (a) and after (b) mineralized collagen coating. Note the additional hydroxyapatite peaks in (b) confirming mineral deposition.