Surface and biological evaluation of hydroxyapatite‐based coatings on titanium deposited by different techniques

Abstract

Hydroxyapatite coatings have been deposited on titanium cp by plasma spray, sol-gel, and sputtering techniques for dental implant applications. The latter two techniques are of current interest, as they allow coatings of micrometer dimensions to be deposited. Coating morphology, composition, and structure have been investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). All coatings were homogeneous and exhibited a rough morphology suitable for implant applications. The sputtered (after annealing), plasma spray, and sol-gel coatings all showed diffraction peaks corresponding to hydroxyapatite. The surface contaminants were observed to be different for the different coating types. The sputtered coatings were found to have a composition most similar to hydroxyapatite; the sol-gel deposits also showed a high concentration of hydroxyl ions. A discrepancy in the Ca/P ratio was observed for the plasma spray coatings, and a small concentration of carbonate ions was found in the sputter-deposited coatings. The in vitro cell-culture studies using MG63 osteoblast-like cells demonstrated the ability of cells to proliferate on the materials tested. The sol-gel coating promotes higher cell growth, greater alkaline phosphatase activity, and greater osteocalcin production compared to the sputtered and plasma-sprayed coatings.

Preparation and biological evaluation of hydroxyapatite-coated nickel-free high-nitrogen stainless steel

“…Similar to the results of our study, several short-term in vitro assays demonstrated that the coated HAp with the micro-roughened surface suppresses the cell adhesion and proliferation, while stimulating the differentiated cell function [59][60][61]. On the other hand, it has been reported that the higher surface area from the micro-roughness is one of the most effective factors for accelerating osseointegration of implant material during long-term implantation in the body.…”

Nanocomposite hydroxyapatite formation on a Ti–13Nb–13Zr alloy exposed in a MEM cell culture medium and the effect of H2O2 addition

“…However, Kumar et al have shown that brushite is soluble in aqueous solutions and (the more stable) HA is subsequently precipitated onto the surface [34]. Air-exposed bulk HA samples show an XPS determined Ca/P ratio close to or slightly lower than the stoichiometric value of 1.67 [32,33,35], whereas a significant reduction in the Ca/P ratio (values close to 1.0) has been found in this and other XPS studies of HA formation in aqueous and physiological solutions [36][37][38]. Amrah-Bouali et al [38] have studied the Ca/P ratio determined by XPS for HA exposed to a range of aqueous and physiological solutions and found that in all cases that the Ca/P ratio after exposure approaches 1.0.…”

Initial responses of human osteoblasts to sol–gel modified titanium with hydroxyapatite and titania composition

“…Various Ti implant modifications including plasma-spraying, ion-beam assisted deposition and coating with calcium phosphate or bioactive glass have been developed to assist in improving this osseointegration process [10]. In this work, sol-gel processing was used to manufacture four different HA/TiO2 surface coatings on Ti, which had previously shown promise over untreated The sol-gel coatings used herein showed uniform coating thickness and similar ranges of roughness.…”

“…Sol-gel methods additionally have a practical advantage of being applicable at mass-production level and of being a simple, relatively low temperature means of surface modification for complex implant shapes [10].…”