OXIDATION OF TITANIUM, RGD PEPTIDE ATTACHMENT, AND MATRIX MINERALIZATION OF RAT BONE MARROW STROMAL CELLS

OXIDATION OF TITANIUM, RGD PEPTIDE ATTACHMENT, AND MATRIX MINERALIZATION OF RAT BONE MARROW STROMAL CELLS
November 6, 2004
By Francis K. Mante, PhD, DMD; Kevin Little, BS; Mamle O. Mante, MS, DMD; Christopher Rawle, BS; George R. Baran, PhD
Journal of Oral Implantology
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Abstract
The aim of this study was to compare the efficacy of attachment of arginine-glycine-aspartic acid (RGD) peptide to titanium surfaces oxidized by different methods. Titanium surfaces were treated as follows: (1) treatment A: passivation in nitric acid, (2) treatment B: heated in air at 400¨?C for 1 hour, (3) treatment C: immersed in 8.8 M H2O2/0.1 M HCl at 80¨?C for 30 minutes, and (4) treatment D: treated as in treatment C and then heated at 400¨?C for 1 hour. RGD was attached to titanium samples treated as in treatments A through D. The quantity of attached RGD was determined by an enzyme-linked immunoabsorbent assay. Mineralization of a rat bone marrow stromal cell (RMSC) culture on the titanium surfaces after 21 days was determined y atomic absorption spectroscopy. The treatments were ranked according to quantity of RGD attached as C, A, B, and D. Twenty-one days after RMSC culture, the degree of mineralization was significantly higher for treatment C than for treatments A, B, and D and for controls. The efficacy of RGD attachment varies with the oxidation treatment given to titanium. Oxidation in H2O2/0.1 M HCl at 80¨?C provided the best overall surface for RGD attachment as well as calcified matrix formation of RMSCs.
INTRODUCTION
Osseointegration of titanium implants is a prerequisite for their success in restoring the dentition. In current use, bone grows into direct contact with the titanium implant surface to achieve successful integration.1,2 This process requires a healing period of 3 to 6 months before restoration of the dentition. Improvements in dental implants that would enable their immediate restoration and loading would be beneficial for restoring immediate function for patients. Both clinical- and basic-science approaches to immediate loading of dental implants are actively being pursued.
Bone formation after implant placement can proceed from the implant bed as well as the implant surface. Bone growth from the implant bed proceeds as a response to injury. The degree to which bone forms from the implant surface toward the implant bed is uncertain but will clearly benefit from having a biologically compatible implant surface.3 Several surface treatments have been studied for preparing a biomimetic titanium implant surface. A biomimetic implant surface close to undifferentiated osteoblast precursor cells in bone marrow should attract bone precursor cells to the implant surface and promote their attachment and differentiation and bone formation from the implant surface. This process will be expected to accelerate osseointegration. Appropriate biological molecules must be identified and their effects on osteoblast function thoroughly investigated to design effective biomimetic implants.