Enhanced osteoconductivity on electrically charged titanium implants treated by physicochemical surface modifications methods

Abstract

Following implantation, dental implant stability can become compromised due to poor bone tissue integration and reactive foreign-body encapsulation. A key tenet of bone tissue engineering is biomimetic design, and in particular, the development of responsive surfaces that promote ion exchange with interfacing tissues, facilitating the ionic events that occur naturally during bone repair, hold promise as orthopedic fixation strategies. Herein, simple thermochemical and oxygen plasma processes are described and assessed in vivo as functional approaches for the development of dental implants with enhanced integration potential. Non-bioactive titanium dental implants treated by shot-blasting and acid-etching (AE) (to produce micro to nanoscale hierarchical topographic structure) induced higher bone implant contact (BIC=53% and 68%) compared to shot-blasted treated (SB) implants (BIC=47% and 49%) at weeks 4 and 8, respectively. Plasma (PL) or thermochemical (BIO) processes were subsequently used to produce a bioactive charged surface by selective ion adsorption as indicated by surface zeta potential changes from-34 mV (SB) to-20mV (PL) or-10 mV (BIO). In addition, an increase on the polar component of surface energy was obtained due to higher number of surface hydroxyl groups as indicated by X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy analyses (EDX). In vivo results showed that charged implants exhibited enhanced osteoconductivity through ionic surface-tissue exchange (PL, BIC= 69% and 73% and BIO, BIC= 83% and 86 % at weeks 4 and 8 respectively). Furthermore, charged bioactive surfaces (PL and BIO) obtained functional mechanical stability as early as 4 weeks post implantation via increased total bone area (BAT=56% and 59%) ingrowth compared to SB (BAT=35%) and AE (BAT=35%) surfaces. This results correlated positively with clinical evaluation of osseointegration using resonance frequency analysis (RFA). This study describes the development and application of surface functionalization methods to selectively modulate surface charges and enhance implant-bone tissue integration.

Enhancement of Intracellular Calcium Ion Mobilization by Moderately but Not Highly Positive Material Surface Charges

“…Some explanations have also been suggested for the surface charge and its effect on the cell-material interaction. Surface charges can generate electrical cues necessary to regulate cell function (De Aza et al, 2003;Finke et al, 2007;Fernández-Yagüe et al, 2019). As human osteoblasts are negatively charged (Rebl et al, 2016), positive surface charges significantly influence cell adhesion (Rebl et al, 2010;Dhowre et al, 2015;Mörke et al, 2017), spreading and proliferation (Staehlke et al, 2019), particularly in the early stages of cell responses.…”

Surface Modification of Porous Titanium and Titanium Alloy Implants Manufactured by Selective Laser Melting: A Review

“…[ 182 ] In addition, TiO 2 nanotubes possess large surface area and strong adsorption ability, making them conducive to the adsorption of immune proteins, [ 183,184 ] and can serve as a transition layer to increase adhesion strength and deposition amount of HA coating. [ 185,186 ]…”

“…[182] In addition, TiO 2 nanotubes possess large surface area and strong adsorption ability, making them conducive to the adsorption of immune proteins, [183,184] and can serve as a transition layer to increase adhesion strength and deposition amount of HA coating. [185,186] In particular, the TiO 2 nanotubes with a unique hollow structure are feasible to deliver drugs, which are currently the most valuable and reliable drug deliverers. [187,188] The drug releasing rate depended on the temperature response characteristics of the thermosensitive hydrogel.…”