Corrosion of phosphate-enriched titanium oxide surface dental implants (TiUnite®) under in vitro infammatory and hyperglycemic conditions

Endosseous dental implants use is increasing in patients with systemic conditions that compromise wound healing. Manufacturers recently have redesigned implants to ensure more reliable and faster osseointegration. One design strategy has been to create a porous phosphate-enriched titanium oxide (TiUnite®) surface to increase surface area and enhance interactions with bone. In the current study, the corrosion properties of TiUnite® implants were studied in cultures of monocytic cells and solutions simulating inflammatory and hyperglycemic conditions. Furthermore, to investigate whether placement into bone causes enough mechanical damage to alter implant corrosion properties, the enhanced surface implants as well as machined titanium implants were placed into human cadaver mandibular bone, the bone removed, and the corrosion properties measured. Implant corrosion behavior was characterized by open circuit potentials, linear polarization resistance, and electrical impedance spectroscopy. In selected samples, THP1 cells were activated with lipopolysaccharide prior to implant exposure to simulate an inflammatory environment. No significant differences in corrosion potentials were measured between the TiUnite® implants and the machined titanium implants in previous studies. TiUnite® implants exhibited lower corrosion rates in all simulated conditions than observed in PBS, and EIS measurements revealed two time constants which shifted with proteincontaining electrolytes. In addition, the TiUnite® implants displayed a significantly lower corrosion rate than the machined titanium implants after placement into bone. The current study suggests that the corrosion risk of the enhanced oxide implant is lower than its machined surface titanium implant counterpart under simulated conditions of inflammation, elevated dextrose concentrations, and after implantation into bone.