Novel nano-micro-hybrid titanium surface for accelerated osseointegration

By taking advantages of nano-surface-structuring technology, there may be opportunities for various materials to have unique physical, chemical, mechanical and biological properties. Current dental implant surfaces, which have been well-established and proven to be successful at a micron level, may need a new nano-level approach to further advance the existing osseointegration capacity.

Objectives: This study assesses osteoconductive potential of newly-developed nano-micro-hybrid titanium surface over the titanium surface with microstructure alone.

Methods: Four different titanium surfaces were created: acid-etched surface (HF+6H2SO4) as a microstructured surface; titanium dioxide (TiO2) depositioned surfaces onto the acid-etched surface with 3 different deposition time as nano-micro-hybrid structured surfaces. Surface morphological profiling was carried out using scanning electron microscop and atomic force microscopy. Rat bone marrow-derived osteoblastic cells were cultured. Osteoblastic proliferation and rate of differentiation were evaluated by the number of cells and reverse-transcriptase polymerase chain-reaction gene expression analysis, respectively. In vivo osseointegration capacity was evaluated by a biomechanical push-in test in the rat femur model.

Results: The different TiO2 deposition time created different sizes of nano-nodular structures: 100nm, 300nm and 500 nm nano-nodules on the existed acid-etch-created microtopography. The nano-nodular structures showed a quite similarity to the surface of cultured osteoblastic mineralized matrix. The proliferation activity was approximately 2 times higher for the nano-micro-hybrid surfaces than for the micro-surface. Bone-related gene expressions were generally upregulated in the cells cultured on nano-micro-hybrid surfaces. Osseointegration strength was also significantly higher for the nano-micro-hybrid surface, with 300 nm nano-nodules generating the greatest strength which was 3-times stronger value of the acid-etched surface.

Conclusion: The titanium with nano-micro-hybrid structure, mimicking the morphological features of the bone-like mineralized matrix surface, has been demonstrated to show higher osteoconductive potential over the surface with microtopography alone, offering a new, breakthrough avenue in developing dental implant surfaces with better osseointegration capability.