The effect of chemical and nanotopographical modifications on the early stages of osseointegration.

PURPOSE

To investigate the effect of chemically modified implants with similar microtopographies but different nanotopographies on early stages of osseointegration.

MATERIALS AND METHODS

Forty screw-shaped implants were placed in 10 New Zealand white rabbits. The implant surface modifications investigated in the present study were (1) blasting with TiO2 and further (2) fluoride treatment or (3) modification with nano-hydroxyapatite. Surface evaluation included topographical analyses with interferometry, morphologic analyses with scanning electron microscopy, and chemical analyses with x-ray photoelectron spectroscopy. Bone response was investigated with the removal torque test, and histologic analyses were carried out after a healing period of 4 weeks.

RESULTS

Surface roughness parameters showed a slight decrease of the average height deviation for the fluoride-treated compared to the blasted (control) and nano-hydroxyapatite implants. Scanning electron microscopic images at high magnification indicated the presence of nanostructures on the chemically modified implants. Chemical analyses revealed the presence of titanium, oxygen, carbon, and nitrogen in all implant groups. The blasted-fluoride group revealed fluoride, and the blasted-nano HA group calcium and phosphorus with simultaneous decrease of titanium and oxygen. Removal torque values revealed an increased retention for the chemically modified implants that exhibit specific nanotopography. The histologic analyses demonstrated immature bone formation in contact with the implant surface in all groups, according to the healing period of the experiment.

CONCLUSION

Chemical modifications used in the present study were capable of producing a particular nanotopography, and together with the ions present at the implant surface, may explain the increased removal torque values after a healing period of 4 weeks.