Abstract

The Effect of Implant Screw Coating with Nano-Hydroxyapatite and Magnesium Chloride Mixture on Osseointegration: Biomechanical and Histological Study

The goal of modern implantology is fine and fast osseointegration which is a major factor influencing the success of dental implantation, and its largely depend on the implant surface. High-quality osseointegration stand for an accelerated healing process, high stability, and durability of the dental implant. Aim: To evaluate the effect of composite material coating which includes ceramic nano hydroxyapatite and magnesium chloride on the bond strength at bone implant interface and tissue reaction. Methods: In in vitro study, a plate of Cp-Ti was coated with hydroxyapatite and MgCl2 by electrophoretic deposition coating technique. Coating procedure was performed using different proportion of hydroxyapatite and MgCl2 and different coating time at fixed voltage. Then analysis of coated surface was performed. The tibia of white male New Zealand rabbits were chosen as implantation sites of 40 screws for in vivo study. Torque removal test was performed to measure bond strength between implant and bone after 2 and 4 weeks healing periods. Results: The results of Energy-dispersive X-ray spectroscopy shows that 1.9% of Mg and 32.4% Ca contain on Ti substrate. Optical microscope examination showed that 2 minutes is the suitable time used for coating screws at 30 V. Analysis of surface roughness in nanoscale was 86.89 nm and grain size 128 nm while scanning electron microscope showed numerous agglomerations of small spherical particles between 5 nm and 100 nm of hydroxyapatite. The torque mean value at bone-implant interface in coated implants was significantly higher than the uncoated implants at 2nd and 4th week. In histological analysis, there was an interdigitating of well-developed bone close opposing threads of coated implants after 2 and 4 weeks implantation. Coating Cp-Ti screws with mixture of hydroxyapatite and MgCl2 was efficient in increasing bone bonding strength to dental implant at bone implant interface than uncoated implant, which was demonstrated by higher torque removal force and increase in bone formation around screw with time.

• PDF