Bone Response to a Pure Titanium Implant Surface Modified by Laser Etching and Microarc Oxidation

Purpose: To compare the bone responses to a pure titanium machined implant surface and one that has been modified by laser etching and microarc oxidation. Materials and Methods: Forty-eight threaded implants with a machined surface were manufactured from rods of commercially pure titanium. The control group consisted of 24 implants with a machined surface. The test group consisted of 24 machined-surface implants that were modified by laser etching and treated by microarc oxidation in an electrolyte solution containing Ca2+ and PO4 3- ions. The implants were analyzed by energy-dispersive x-ray and scanning electron microscopy. Next, the two types of implants were inserted in the tibiae of 12 New Zealand White rabbits; one of the two tibiae received two control implants and the opposite side received two test implants. After 2, 4, and 6 weeks, the rabbits were sacrificed. Prior to sacrifice, all rabbits were injected with fluorescent-labeled achromycin and calcein. Samples were cut and ground for histomorphologic observation, and the mineralization appositional rate and the osseointegration index were measured and analyzed. Results: Proportional spacing craters were found with a diameter of 100 µm and a depth of 80 to 100 µm at intervals of 100 µm around the test surface, and a porous titanium dioxide coating on the surface with pores of 1 to 5 µm in diameter was also produced. Carbon, oxygen, calcium, and phosphonium were detected by electronic probe. The ratio of calcium to phosphonium was 1.418, and the crystal structure of x-ray diffractive patterns indicated pure anatase phases. Compared with the control samples, the mineralization ratio and the osseointegration index of the bone around the test implants were higher (P = .00). Conclusions: The porous titanium dioxide coating produced by laser etching and microarc oxidation treatment improved the bone response versus that seen around machined titanium implants and enhanced the bone formation rate. It was concluded that the surface chemistry and topography, either separately or together, play an important role in the bone response to implants. Keywords: implant, laser, microarc oxidation, osseointegration, rabbit, titanium