Bioactive Modification Study Of Multifactor Porcelainization On Titanium Dental Implant Surface

Known as a newly-developed and promising subject, oral implantation has experienced more than half a century's devious development and uninterrupted improvement. Nowadays, it has been accepted by doctors and patients throughout the world, and prevailed considerably in clinical field. Among metal, carbon, ceramic, macromolecular compound and even many complex materials, there are more than dozens of alternatives for dental implants materials. Pure titanium is preferred as oral implants materials after years of clinical practices, contributing to its excellent biocompatibility and mechanical characters. At the same time, some disadvantages, such as long concrescence period and low bonding power, have been emerging along with the elevated clinical demands. As a result, bioactive surface modification of dental implants became one of research emphasises, which aims to improve bioactivity of implants materials and acquire firmer implants-bone bonding in shortened concrescence period. Study objectivesAccording to microarc oxidation(MAO) and electrophoresis theories, electrolytes and electrical parameters were adjusted and improved on the base of present study of MAO technique for aluminum alloy and titanium alloy, so as to develop a new method for bioactive modification of pure titanium dental implants surface, by which the natural oxide layer on titanium implants could be transformed into a multifactor complex ceramic film with good bioactivity and bone-like apatite inducement ability. Dental implants with the multifactor complex ceramic film inserted in vivo were expected to chemically bond to bone tissues and increase the bonding power, simultaneously induce the deposition of calcium phosphate, stimulate bone growth and rebuild process in shortened implants-bone concrescence period. If this new type of dental implants with multifactor complex ceramic film could be adopted for dental implants in clinical use, the clinical treatment period of two-stage implants surgery could be shortened, with the bone bonding power in initial stage be strengthened and success rate of implants surgery be increased. Methods & resultsFirst of all, electrolytes and electrical parameters were assessed to find out the influence rule on MAO surface treatment for pure titanium, so as to acquire a new MAO technique eligible for oral implants. High energy pulse DC power, a series of electrolytes and electrical parameters were adopted, based on hybrid microarc oxidation-electrophoresis (MAO-EP) theory, to study the actual electrochemical reaction rules and find out the optimal techniques. Pure titanium specimens were treated by MAO-EP method, withsurface micro-appearance, roughness, surface energy, ceramic film thickness, porosity rate, composition and structure of surface were tested and analyzed statistically. A film of 8.5-micron thickness with high surface energy (63.7 mJ/m2), high roughness(Ra=1.548 , Rz=6.811),and high porosity rate(16%) composed of titanium dioxide and calcium phosphate, especially hydroxyapatite was formed on the surface of pure titanium by the chosen MAO-EP techniques.Cell culture fluid including protein and amino acid was chosen as simulated body fluid to perform the in vitro deposition inducement experiment of pure titanium materials treated by MAO-EP method. The micro-appearance of the specimens were observed by SEM at 6d, 12d, 24d, with the surface composition and structure tested by EDS and XRD. SEM results indicated dissolve and re-deposition of calcium phosphate on the surface of MAO-EP specimen and apparent rebuild of surface micro-appearance with the soak period prolonged. EDS results indicated the increase of calcium, phosphor, oxygen element and decrease of titanium. The content of calcium and phosphor at 6d already reached a rather high proportion, which accorded with the surface micro appearance. The depositions on the specimen surface were mainly composed of crystalline hydroxyapatite and other kinds of calcium phosphate.To assess the bio compatibility of the MAO-EP titanium surface, hemolys...