The Study Of Modification On The Surface Of The Titanium Miniscrews

Objectives: In order to improve the bioactivity of titanium mini-implants,to improve its abrasion performance and corrosion resistant and to promote the early bonding of the implant with bone tissue,samples of miniscrew were treated in different electrolytes by electrochemical deposition technology. 2 kinds of coatings with different chemical composition were got and biological evaluation were investigated.We hope to provide a theory base for surface modification of titanium implant.At the same time ,there are some difficult cases such as the maxillary develop not enough, and the anchorge lost . All of these cases need the help of the miniscrews to provide more force. We hope the modificated miniscrews will provide a better choice for the usage in clinic.This experiment contains three parts:1. Preparation of the Nanosilver-containing hydroxyapatite coatings by electrochemical deposition technology on the surface of the titanium miniscrewmethod: Use the electrochemical deposition technology to deposit a HAp/Nanosilver composite coating on the surface of miniscrews. The electrodeposition was carried out to form a DCPD/nanosilver coating on the surface of miniscrew in the solution containing CaCl₂, NaH₂PO₄, AgNO₃ and KI. The DCPD/nanosilver composite coating was then transformed to HAp/Nanosilver by the treatment in 2.5M NaOH at 75℃for 3h. Scanning electro-microscope (SEM), and X-ray energy dispersive spectrometer (EDS) were employed to characterize the obtained coating. Results The electrodeposition was successfully carried out to form a HAp/Nanosilver coating, and the diameter of Nanosilver was about 200～400nm. Conclusion: The HAp/Nanosilver bioceramic coating on the titanium miniscrew surface was successfully carried out.2. Preparation of the hydroxyapatite coatings by electrochemical deposition technology on the surface of the titanium miniscrewMethod Use the electrochemical deposition technology to deposit a HAp coating on the surface of miniscrew in the solution with the Ca/P is 1.67, pH is 6.3 under the condition of the solution boiling to get the HA nanopaticle coating. Scanning electro-microscope (SEM), and X-ray energy dispersive spectrometer (EDS) were employed to characterize the obtained coating. Results The electrodeposition was successfully carried out to form a HAp coating, and the diameter of HA nanopaticle 1-100nm like the acicular crystal. Conclusion: The HAp coating on the titanium miniscrew surface was successfully carried out.3.The biological evaluation of miniscrew(1)Haemolysis experiment: Method: Get the fresh blood from the rabbit and diluted the solution to the right consistency. put the titanium miniscrews with the HAp/nannosilver coating and HAp coating separately in the cuvette with 10 mL physiological saline solution as the test group, while those in the cuvette with 10 mL distilled water and 10 mL physiological solution were taken as the positive control group and the negative control group. The dilute The dilute rabbit blood (0.2 mL) was added into each cuvette. measure the digit of OD to get the haemolysis rate. Result The haemolysis rate the HAp coating is 0.58% and the HAp/nanosliver is 1.15% . Conclusion:The miniscrew which contains the HAp/Nanosilver coating and the HAp coating has a good blood compatibility .(2)Anti-bacterial experiment: Method: Use the titanium plates which contain the HAp/nanosliver and the HAp coating as the test groups and the pure titanium plates as the control group .use the Streptococcus as the test bacterial to exam the anti-bacterial rate by counting the cfu ,Result The test group with the HAp/nanosilver have good antibacterial function its rate is 89.1% and the HAp coating group shows insighnifant function of the antibacterial ,its rate is 3.4%. Conclusion:The titanium plates contain the HAp/nanosliver have a good anti-bacterial capability, while titanium plates contain the HAp have no anti-bacterial capability .