Removal of HA and TPS implant coatings and fibroblast attachment on exposed surfaces

The removal of implant coatings may be necessary if rough implant surfaces are exposed subgingivally due to progressive peri-implant bone loss or if t hey are also supragingivally exposed because of progressive gingival recess ion, thus facilitating plaque formation and impairing tooth cleaning done a t home. The aim of this experimental study was to develop diamond-coated fi les and rubberized polishers for machine-driven instrumentation of implant cylinders, and present an instrumentation concept for the complete removal of rough titanium plasma spray (TPS) and hydroxylapatite (HA) layers and po lishing exposed titanium surfaces. The surface structure and its possible c ontamination by the instrumentation process was investigated using laser pr ofilometry, scanning electron microscopy, and x-ray fluorescence analysis. The effect of impurities on the growth of human fibroblasts was tested in c ell culture. The results show that TPS and HA implant coatings can be remov ed with the modified implant files. After polishing the exposed titanium su rfaces, roughness depths of Rz= 4.6 mum (TPS) and Rz=5.7 mum (HA) and, for implant cylinders, 3.4 mum were found. During the instrumentation of implan t surfaces, contamination with the material of the instrument must be expec ted. It was shown that, in principle, growth of human gingival fibroblasts on the instrumented surfaces is possible. The cells were intimately associa ted with one another and, compared to culture controls, demonstrated good a dhesion with strict orientation to the microstructure of the scoring left b y instrumentation. The biological consequences and mechanisms of cell adhes ion on instrumented surfaces require further investigation.