Physical stability of arginine-glycine-aspartic acid peptide coated on anodized implants after installation

Abstract

Purpose: The aim of this study was to evaluate the stability of arginine-glycine-aspartic acid (RGD) peptide coatings on implants by measuring the amount of peptide remaining after installation.

Materials and methods: Fluorescent isothiocyanate (FITC)-fixed RGD peptide was coated onto anodized titanium implants (width 4 mm, length 10 mm) using a physical adsorption method (P) or a chemical grafting method (C). Solid Rigid Polyurethane Foam (SRPF) was classified as either hard bone (H) or soft bone (S) according to its density. Two pieces of artificial bone were fixed in a customized jig, and coated implants were installed at the center of the boundary between two pieces of artificial bone. The test groups were classified as: P-H, P-S, C-H, or C-S. After each installation, implants were removed from the SRPF, and the residual amounts and rates of RGD peptide in implants were measured by fluorescence spectrometry. The Kruskal-Wallis test was used for the statistical analysis (α=0.05).

Results: Peptide-coating was identified by fluorescence microscopy and XPS. Total coating amount was higher for physical adsorption than chemical grafting. The residual rate of peptide was significantly larger in the P-S group than in the other three groups (P<.05).

Conclusion: The result of this study suggests that coating doses depend on coating method. Residual amounts of RGD peptide were greater for the physical adsorption method than the chemical grafting method.

Keywords: Chemical grafting; Dental implant; Physical adsorption; Physical stability; RGD peptide.

Fig. 1

Schematic representation of the chemical grafting group.

Fig. 2

Implant installation using a machine developed by Osstem Co. (Pusan, Korea). This machine was set at a given direction and rotation speed (30 rpm); drill burs up to 3.5 mm can be used for the installation of 4.0 mm implants.

Fig. 3

Divided surface of a SRPF; A: After implant installation, B: each SRPF was divided into 2 pieces and the implant was removed.

Fig. 4

Schematic diagram of RGD-peptide quantitation. B - A = amount of RGD peptide remaining on an implant after installation. C - (B - A) = amount of RGD peptide lost from the implant surface.

Fig. 5

SEM micrographs of each group, no differences were observed after coating with RGD peptide; A&B: bare anodized titanium, C&D: physical adsorption group, E&F: chemical grafting group; A,C,E: ×50,000, B,D,F: ×100,000.

Fig. 6

Fluorescence microscopic images after RGD-peptide coating (A: bare anodized titanium, B: physical adsorption group, C: chemical grafting group, bar: 200 µm). Fluorescence was greater in the physical adsorption group than in the chemical grafting group. Implants surfaces were yellower in the physical adsorption group. Green dot-like areas were sparsely present in both the physical adsorption and chemical grafting groups.