A novel multiphase anodic spark deposition coating for the improvement of orthopedic implant osseointegration: An experimental study in cortical bone of sheep

Abstract

The effect of a new three-step anodic spark deposition process, labeled TiSpark, including two consecutive treatments performed first in a P solution and second in Ca solution, followed by an additional alkali etching step, was investigated for the improvement of osseointegration of commercial grade 2 titanium, machined (Ti) or Al(2)O(3) sandblasted (Ti-SA), cylindrical implants (12 mm in length and 4 mm in diameter) in cortical bone of 12 adult sheep. Histomorphometric and microhardness measurements were carried out at each experimental time (4, 8, and 12 weeks) to quantify the bone-to-implant contact around the implants as well as the newly bone hardness and bone maturation index. TiSpark treated surfaces were covered by a thick layer of crystalline anatase TiO(2) and by a further Ca/P layer. Bone tissue extends and grows on the surface of the TiSpark treated implants without any fibrous tissue, enhancing the short-term osseointegration properties of implant. Bone mineralization rate was also influenced by the chemical composition of implants and sandblasted materials presented the lowest bone maturation rate at the interface. Data suggests that the TiSpark treatment produces a modification of the Ti surface, which presents good bioactivity and may be suitable for achieving a stable implant osseointegration.

In vitro cellular response and in vivo primary osteointegration of electrochemically modified titanium

“…These results are in agreement with previously published data [30,[35][36][37][38], although a direct comparison is not appropriate due to differences in animal models, experimental methods, surgical procedures and experimental times. For example, Chiesa et al [30], in a study on the fixation dynamics of spark modified and control titanium in sheep, demonstrated a statistically significant increase in the bone-implant contact for spark titanium at 4 and 8 weeks, but saw no statistically significant differences at 12 weeks.…”

“…Previous studies evaluated the osteointegrative potential of these surfaces in the rat and the sheep by means of histology and static histomorphometry at time points between 4 and 12 weeks after surgery [30,[35][36][37][38]. Pertaining to the in vivo performance of these surfaces, the present work aims to evaluate the osteogenic primary response to implanted surfaces using a short (within 4 weeks) experimental time frame.…”

“…ETC treatment was capable of modifying the morphology at a micrometric level through a chemical dissolution process at the metal surface, with no detectable modification of the chemical composition. On the other hand, although the SEM morphology of BS and OS was very similar, the qualitative chemical composition assessed by EDS analysis revealed for both BS and OS surfaces Ca and P peaks, indicating calcium and phosphorus enrichment of the titanium oxide layer, but evidenced traces of Na and K on BS and OS specimens, respectively, resulting from the final different alkali treatment procedures (data not shown) [24,38].…”

“…The morphological, chemical and physical characterization of ETC, BS, and OS surfaces were discussed elsewhere [30,38,51]. ETC treatment was capable of modifying the morphology at a micrometric level through a chemical dissolution process at the metal surface, with no detectable modification of the chemical composition.…”

“…Considering the in vivo performance of these surfaces, the present work aims to evaluate the osteogenic primary response to implanted surfaces within a short experimental time frame of 4 weeks, an extension on previous osteointegration studies [30,[35][36][37][38]. For this purpose, the White New Zealand rabbit was chosen as the animal model, and histology, static and dynamic histomorphometry were considered.…”