Extended bioactivity in the proximity of hydroxyapatite ceramic surfaces induced by polarization charges

Abstract

Surface charges of electrically polarized hydroxyapatite (HAp) ceramics were demonstrated to enhance osteoconductivity in the wide gap of the canine bone whereas the bone formation processes varied according to the charge polarity. Cell reactions in the vicinity of the charged surfaces of HAp ceramics were not phagocytic absorption but rather bone formation by stimulated osteoblasts surrounding newly formed bone 7 days after implantation. The bone formation in direct contact with negatively charged ceramic surfaces suggests that the negative charges enhanced the osteobonding ability of the HAp ceramics. In the vicinity of the positively charged HAp surface, the formation of bones derived from osteoid tissues entirely occupied the 0.2-0.3-mm gaps between the HAp and the bone at 7 days. Surface charges induced by electrical polarization significantly cooperated with the innate bioactivity of HAp and reconstructed the wide bone defects more promptly than did the nonpolarized HAp ceramic surface.

Numerical osteobonding evaluation of electrically polarized hydroxyapatite ceramics

“…2). The average of the total stored charges (3.9 Ccm Ϫ2 ) with small deviations of Ͻ10% calculated from TSC spectra of almost all of the samples corresponded well to the published results [5][6][7]12 and proved to be electrically polarized and to store huge charges. Specimens beyond tolerance were omitted.…”

“…8,9 The obtained HA specimens with a size of 10.0 ϫ 5.0 ϫ 0.7 3 were identified by conventional X-ray diffractometry (XRD) and FT-IR spectrometry and electrically polarized in a dc field of 1.0 kVcm Ϫ1 with a pair of Pt electrodes in air at 300°C for 1 h. [5][6][7] The polarization charge confirmation of one of the three samples chosen at random was examined by the thermally stimulated current (TSC) method with a HewlettPackard 4140B pA meter 4 [ Fig.1(a)]. Polarized and nonpolarized HA specimens sterilized by an ethylene oxide gas method were implanted in the femoral and tibial diaphyses of 10 male New Zealand white rabbits.…”

“…6 In the vicinity of the positively charged HA surfaces, the formation of bone derived from osteoid tissue entirely occupied the gaps. 7 Within 4 weeks, almost perfect bone reconstruction occurred accompanied with activated osteoblastic cells, with the processes varying according to the charge polarity.…”

Chemico-Vector and Mechanochemico-Vector Properties of Polarized Glass-Ceramic Silicophosphate of Narpsio

“…Polarization is important in biomaterials, since we have more recently demonstrated by in vitro and in vivo tests that the charged surfaces of electrically polarized hydroxyapatite 9,10 acquired enhanced osteoconductivities. [11][12][13] This study will demonstrate the electrical polarizability and in vitro biocompatibility or chemico-vector effect of gc: Narpsio.…”

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“…Furthermore, a growth of both biomimetic calcium orthophosphates and bones was found to be accelerated on negatively charged surfaces and decelerated at positively charged surfaces [340][341][342][343][344][345][346][347][348][349]. In addition, the electrical polarization of HA bioceramics was found to accelerate a cytoskeleton reorganization of osteoblastlike cells [350][351][352], extend bioactivity [353] and enhance bone ingrowth through the pores of porous HA implants [354]. There is an interesting study on the interaction of a blood coagulation factor on electrically polarized HA surfaces [355].…”