Periodontal-like gingival connective tissue attachment on titanium surface with nano-ordered spikes and pores created by alkali-heat treatment

Objectives Establishment of periodontal-like connective tissue attachment is one of the outstanding issues in implant dentistry. Organized nanotopographic titanium surface may acquire periodontal-like connective tissue attachment with activation of fibroblastic function. This study aimed to evaluate gingival fibroblastic function and connective tissue attachment on two types of nanotopographic titanium surface created by alkali-heat (AH) treatment. Methods Commercially pure titanium turned discs with or without acid-etching or two types of AH treatment, underwent scanning electron microscopic evaluation in surface topography. Rat gingival fibroblasts cultured on the discs evaluated in terms of cellular adhesion, collagen synthesis and physicochemical binding strength of deposited collagen on the surfaces. Turned or the AH-treated pure titanium mini-implants were placed on the hard palatal plate of rabbits and underwent histological evaluation at 8 weeks postoperatively. Results Both AH-treated surfaces were characterized by numerous well-organized fine nanospikes with crevasses and nanoholes, and uniform shaggy-like nanotopography with a sponge-like inner network, respectively. These nanotopographic surfaces enhanced cellular adhesion and collagen synthesis and toughened binding strength of deposited collagen sufficiently to resist against experimental overloading and inflammatory conditions by inclusion of collagen fibers into the surface, as compared with turned or acid-etched surfaces. The AH-treated mini-implants yielded inclusion of gingival connective tissue into the nanotopographic surface structure, with collagen fiber directions mimicking periodontal tissue in the transmucosal area. These features were not seen on turned surface implants. Significance The well-organized nanotopographic titanium surface with nanospikes and pores by the AH treatment enhanced gingival fibroblastic collagen synthesis and acquired periodontal-like connective tissue attachment with substantial detachment resistance.