Cytotoxicity And Genotoxicity Of Amino-group Functionalization On Titanium Implant Surface

Objective and background:Osseointegration, defined as a direct integration between dental implantand bone with no fibrous tissue included in the integration. This definition,was not only the therotical basis of the oral implantology, but also the goldenstandard of determining the success of oral implant.As a bio-inert metal, titanium has got poor bio-activity and withoutosteo-inductive potential, in order to improve the bio-activity of titaniumimplants, various types of surface modification which could enhance theosseointegration and shorten the healing peroid were focused by world-widescholars.Our research group has already successfully induced the amino-group tothe titanium surface through the low temperature plasma technique, andvarious tests were finished to evaluate the mechanical, chemical, andbiological features of the surface-modified material. Our former researchinduced that the amino-group functionalized titanium surface could enhancethe proliferation,early-stage adhesion and the mineralization of theosteoblasts, and improve the deposition of hydroxylapatite on its surface, ourformer research indicated that the amino-group functionalized titaniumsurface could improve the biological activity of pure titanium,therefore thiskind of functionalized surface could improve the bone regeneration andenhance the osseointegration at the bone-implant surface.While the ISO-10993-3-2009and ISO10993-5-2009criteria formulated that medical materials which would stay within the body for longer than30days must be evaluated for their genotoxicity and cytotoxicity. In order toevaluate the clinical feasibility for this kind of material as dental implant, thegenotoxicity and cytotoxicity test seemed to be necessary.Methods:Our research has applied the the Plasma Enhanced Chemical VapourDecomposition method to decompose the amino-groups onto the surface ofpure titanium disks from heyptylamine, parameters of functionalizationtowards titanium disk were concluded from our former research: CW, P(30%)and CW+P(30%), CW is the abbreviation of Continuous Wave, while P standsfor Pulse.The negative control group for all tests were the cleaned andpolished pure titanium disks. The CCK-8assay was applied to evaluate thecytotoxicity of each group,while SCGE test and Micro-nucleus test weretogether used to evaluate the genotoxicity for each group. The data collectedwere measured by SPSS software for statistic analysis.Result:1:CCK-8result: None of these functionalized groups were displayed ofcytotoxicity potential, and the proliferation of the osteoblasts on the surface ofeach experimental group was not inherited compared with the pure titanium.2.SCGE result: All three SCGE parameters for each functionalized groupdisplayed significant differences with the pure titanium, the result indicatedthat compared with the pure titanium group, the amino-group functionalizedtitanium disks would not lead to more DNA damage.3.Micro-nucleus test result: The micro-nucleus test showed that none ofthese three treated groups have got higher rate of micro-nucleus formation,nucleoplasmid buds formation and nuclear blebs formation. The resultindicated that compared with the pure titanium disks, the treated groups would not created more chromosomal aberration and spindle damage.Conclusion:1.Amino-group functionalized titanium surface has got no cytotoxicitytowards osteoblasts, and this treated surface would not restrain theproliferation of the osteoblasts;2.Amino-group functionalized titanium surface would not lead to moreDNA damage to the osteoblasts than the cleaned and polished pure titaniumdoes;3.Amino-group functionalized titanium surface would not lead to morechromosomal abberation than the pure titanium does, and the damagetowards spindle of the treated groups showed no significant difference withthe pure titanium.4.This thesis indicated the amino-group functionalized titanium surfacewas of no cytotoxicity and genotoxicity, this kind of implant surface wouldhave a profound biological safety, and our test showed that this kind ofmodified titanium surface could be feasible for future clinical application, andprovided a theoretical support for that.