Abstract
The most ideal implant models in the dental and orthopedic fields to minimize the failure rate of implantation involve the improvement of osseointegration with host bone. Therefore, a focus of this study is the preparation of surface-modified titanium (Ti) samples of disc and screw types using dexamethasone (DEX) and/or growth and differentiation factor-5 (GDF-5), as well as the evaluation of their efficacies on bone formation in vitro and in vivo. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle measurement were used to evaluate the surface chemical composition, surface morphology and wettability, respectively. The results showed that implant surfaces were successfully modified with DEX and/or GDF-5, and had rough surfaces along with hydrophilicity. DEX, GDF-5 or DEX/GDF-5 on the surface-modified samples were rapidly released within one day and released for 28 days in a sustained manner. The proliferation and bone formation of MC3T3-E1 cells cultured on pristine and surface-modified implants in vitro were examined by cell counting kit-8 (CCK-8) assay, as well as the measurements of alkaline phosphatase (ALP) activity and calcium deposition, respectively. MC3T3-E1 cells cultured on DEX/GDF-5–Ti showed noticeable ALP activity and calcium deposition in vitro. Active bone formation and strong osseointegration occurred at the interface between DEX/GDF-5–Ti and host bone, as evaluated by micro computed-tomography (micro CT) analysis. Surface modification using DEX/GDF-5 could be a good method for advanced implants for orthopaedic and dental applications.
Highlights
Titanium (Ti) and its alloys have been widely used as implants in the orthopedic and dental fields due to their good mechanical properties and biocompatibility [1]
The peaks at 1.99 ppm, 5.02 ppm and 5.35 ppm were assigned to the acetyl group of N-Acetyl-D-glucosamine in the molecular structure of heparin, the H1 of 6-monodeoxy-6-monoamino-β-cyclodextrin (β-CD–NH2) and the H1 of D-glucuronic acid, respectively
Some researchers found that dexamethasone acetate (DEX) or growth and differentiation factor-5 (GDF-5) surface modification improve the proliferation, alkaline phosphatase (ALP) activity, calcium deposition and the expression of bone-related mRNA genes of osteoblast cells cultured on the surface-modified implants [14,25]
Summary
Titanium (Ti) and its alloys have been widely used as implants in the orthopedic and dental fields due to their good mechanical properties and biocompatibility [1]. Several physical and chemical surface modification methods, such as machining, grinding, polishing, blasting, acid-etching, hydrogen peroxide (H2O2)-etching, alkali-etching, sol-gel coating, anodic oxidation, and chemical vapor deposition and coating, have been developed for improving osseointegration [2,3,4]. The primary hydroxyl group of β-CD can be substituted with an amine group [9], allowing for the conjugation with the carboxyl group of heparin through amide bond formation This surface modification has not yet been reported, and would be beneficial for dental and orthopaedic implants. The impact of surface-modified Ti disc samples on MC3T3-E1 cell function was investigated in a series of in vitro tests, including cell proliferation evaluation, alkaline phosphatase (ALP) activity and calcium deposition. The in vivo animal tests including micro-computed tomography (micro-CT), removal torque and histological evaluations were carried out using a rabbit tibia defect model
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