The
demand for medical implants globally has increased significantly
due to an aging population amongst other reasons. Despite the overall
increase in the survivorship of Ti6Al4V implants, implant infection
rates are increasing due to factors such as diabetes, obesity, and
bacterial resistance to antibiotics. Two commonly found bacteria implicated
in implant infections are Staphylococcus aureus and Pseudomonas aeruginosa. Based
on prior work that showed nanostructured surfaces might have potential
in passively killing these bacterial species, we developed a hierarchical,
hydrothermally etched, nanostructured titanium surface. To evaluate
the antibacterial efficacy of this surface, etched and as-received
surfaces were inoculated with S. aureus or P. aeruginosa at concentrations
ranging from 102 to 109 colony-forming units
per disc. Live/dead staining revealed there was a 60% decrease in
viability for S. aureus and greater
than a 98% decrease for P. aeruginosa on etched surfaces at the lowest inoculum of 102 CFU/disc,
when compared to the control surface. Bactericidal efficiency decreased
with increasing bacterial concentrations in a stepwise manner, with
decreases in bacterial viability noted for S. aureus above 105 CFU/disc and above 106 CFU/disc
for P. aeruginosa. Surprisingly, biofilm
depth analysis revealed a decrease in bacterial viability in the 2
μm layer furthest from the nanostructured surface. The nanostructured
Ti6Al4V surface developed here holds the potential to reduce the rate
of implant infections.
Inspired by observations that the natural topography observed on cicada and dragonfly wings may be lethal to bacteria, researchers have sought to reproduce these nanostructures on biomaterials with the goal of reducing implant-associated infections. Titanium and its alloys are widely employed biomaterials with excellent properties but are susceptible to bacterial colonisation. Hydrothermal etching is a simple, cost-effective procedure which fabricates nanoscale protrusions of various dimensions upon titanium, depending on the etching parameters used. We investigated the role of etching time and the choice of cation (sodium and potassium) in the alkaline heat treatment on the topographical, physical, and bactericidal properties of the resulting modified titanium surfaces. Optimal etching times were 4 h for sodium hydroxide (NaOH) and 5 h for potassium hydroxide (KOH). NaOH etching for 4 h produced dense, but somewhat ordered, surface nanofeatures with 75 nanospikes per µm2. In comparison, KOH etching for 5 h resulted sparser but nonetheless disordered surface morphology with only 8 spikes per µm2. The NaOH surface was more effective at eliminating Gram-negative pathogens, while the KOH surface was more effective against the Gram-positive strains. These findings may guide further research and development of bactericidal titanium surfaces which are optimised for the predominant pathogens associated with the intended application.
Titanium and its alloys are frequently the biomaterial
of choice
for dental implant applications. Although titanium dental implants
have been utilized for decades, there are yet unresolved issues pertaining
to implant failure. Dental implant failure can arise either through
wear and fatigue of the implant itself or peri-implant disease and
subsequent host inflammation. In the present report, we provide a
comprehensive review of titanium and its alloys in the context of
dental implant material, and how surface properties influence the
rate of bacterial colonization and peri-implant disease. Details are
provided on the various periodontal pathogens implicated in peri-implantitis,
their adhesive behavior, and how this relationship is governed by
the implant surface properties. Issues of osteointegration and immunomodulation
are also discussed in relation to titanium dental implants. Some impediments
in the commercial translation for a novel titanium-based dental implant
from “bench to bedside” are discussed. Numerous in vitro studies on novel materials, processing techniques,
and methodologies performed on dental implants have been highlighted.
The present report review that comprehensively compares the in vitro, in vivo, and clinical studies
of titanium and its alloys for dental implants.
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