Original Influence of Fibronectin Immobilization on the Orientation of Collagen Bundles in Soft Tissue around Zirconia Implants

In the present study, the soft tissue response toward a fibronectin-immobilized zirconia implant was evaluated by animal experiment. Quartz crystal microbalance (QCM) analyses for atelocollagen adsorption to zirconia were also performed. Cylindrically shaped yttria stabilized tetragonal zirconia polycrystals (Y-TZP) was sandblasted and acid etching- treated (SLA/Y-TZP). Fibronectin-immobilized Y-TZP (Fn/Y-TZP) was obtained using the tresyl chloride-activated method. Implants were placed in the tooth socket of the extracted maxillary teeth of rats. Soft tissue responses 3-weeks after implantation were observed. Long collagen fibers perpendicularly oriented to the Y-TZP implant surface were more abundant in Fn/Y-TZP than in SLA/Y-TZP. The lengths of vertically oriented collagen fibers on the palatal side and the total of the buccal and palatal sides of Fn/Y-TZP were significantly higher than that of SLA/Y-TZP. Fn/Y-TZP showed a significantly higher area of vertically oriented collagen fibers on the buccal side and the total sides as compared to SLA/Y-TZP. There were no significant differences among the ratios of epithelial attachments to fibrous attachments. QCM analyses indicated that the pre-adsorption of fibronectin significantly decreased the amounts of atelocollagen adsorption. In conclusion, the immobilization of fibronectin had a clear effect on the orientation of gingival fibers toward the zirconia implant surface. Atelocollagen adsorption to zirconia was influenced with by fibronectin pre-adsorption.