Effects of calcium‐modified titanium implant surfaces on platelet activation, clot formation, and osseointegration

Abstract

The clinical success of load bearing dental and orthopedic implants relies on adequate osseointegration. Because of its favorable properties, titanium is generally considered as the material of choice. Following implant placement, titanium surfaces establish an ionic equilibrium with the surrounding tissues in which calcium plays major roles. Calcium is a cofactor of the coagulation cascade that mediates plasma protein adsorption and intervenes in a number of other intra and extracellular processes relevant for bone regeneration. In this study, titanium surfaces were modified with calcium ions (Ca(2+) surfaces) and their responses to in vitro and in vivo models were analyzed. Unlike unmodified surfaces, Ca(2+) surfaces were superhydrophilic and induced surface clot formation, platelet adsorption and activation when exposed to blood plasma. Interestingly, in vivo osseointegration using a peri-implant gap model in rabbit demonstrated that Ca(2+) surfaces significantly improved peri-implant bone volume and density at 2 weeks and bone implant contact at 8 weeks as compared to the unmodified controls. The combination of Ca(2+) surfaces with plasma rich in growth factors produced significantly more bone contact already at 2 weeks of implantation. These findings suggest the importance of the provisional matrix formation on tissue integration and highlight the clinical potential of Ca(2+) titanium surfaces as efficient stimulators of implant osseointegration.

Effects of calcium ions on titanium surfaces for bone regeneration

“…We have reported previously that such diffusion accounts for around 70 % of the total surface calcium that it promotes surface-bound coagulation and platelet activation in the microenvironment of the implant surface. [6] Although here we have used a different technique (ICP) and a different substrate geometry (discs instead of implants), in this work we have reached a comparable result (66 %). The difference is presumably due to the duration of the sustained release that ensues.…”

“…The values obtained were similar to those reported previously. [6] When no further chemical modification was applied (NoCa 2+ ), samples were ß-ray sterilized and stored until use. Unless otherwise stated, calcium-ion modified surfaces (Ca 2+ ) were prepared by sonication during 30 s in a bath containing 5 wt.…”

“…[4] However, only a few report on the effects of free calcium ions, which can be readily released to the implant microenvironment. [5][6][7] A recent study of these two strategies in vivo and found statistically significant new bone formation at implants modified with free calcium ions compared with implants coated with a nanometric calcium phosphate deposition. [7] Calcium ions (Ca 2+ ) are centrally involved in a multitude of biological processes, among which the entire lifecycle of bone from formation to repair.…”

The Role of Titanium Surface Nanostructuring on Preosteoblast Morphology, Adhesion, and Migration

“…However, the majority of chemical methods modify not only topography, but also other surface features such as chemical composition, [25] wettability, [26] crystallinity, [27] and adsorption ability. [28] These surface observables can also modulate cell behavior [27,[29][30][31] (for more information about surface modification strategies and cellular recognition of these surfaces see the review papers [32,33] ) and it is difficult to distinguish which factor leads to the observed cell response.…”

Novel Development of Biocompatible Coatings for Bone Implants

“…Amongst the different minerals that were studied, researchers found that calcium is an especially beneficial surface-enriching molecule because it has been proven to be very osteo-inductive and is very effective at encouraging bone formation around the implants. Anitua et al demonstrated that the incorporation of calcium ions onto the surfaces of biomaterials promoted near bone growth in rabbits' femora [12]. Similarly, other animal studies also confirmed the beneficial effects of calcium, such as improved bone formations in rat femora, increased healing of intrabony defects in dog mandibles, and enhanced resistance to dislodgement in rabbit tibia [13][14][15].…”