Oriented bone regenerative capacity of octacalcium phosphate/gelatin composites obtained through two-step crystal preparation method.

The present study was designed to investigate whether composite of coprecipitating octacalcium phosphate and gelatin (C-OCP/Gel) has an effect in repairing critical-sized defect of rat calvaria with oriented regenerative bone if implanted. The materials were prepared through two steps to disperse homogenous and well-elongated OCP toward long axis of the crystals in gelatin (Gel) matrix with the distinct concentration 17-44 wt %: OCP precipitates recovered from the coprecipitated with Gel molecules in aqueous solution (referred to as C-OCP hereafter) were mixed again in fresh aqueous Gel solution with various mixing ratio to form C-OCP/Gel for implantation. C-OCP/Gel disks with 9 mm diameter and 1 mm thickness after the dehydrothermal treatment was implanted in 9 mm diameter rat calvaria critical-sized defect. The histology, the histomorphometry in the regenerated bone and the quantitative analysis of the orientation of collagen with picrosirius red staining were carried out. It was found that C-OCP/Gel is capable of not only inducing sufficiently regenerative bone over 80% of the defect coupled with practically complete material biodegradation but also forming oriented bone significantly in relation to the amount of C-OCP in Gel matrix until 12 weeks after the implantation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1029-1039, 2017.

Biomechanical evaluation of Ti-Nb-Sn alloy implants with a low Young's modulus.

Dental implants are widely used and are a predictable treatment in various edentulous cases. Occlusal overload may be causally related to implant bone loss and a loss of integration. Stress concentrations may be diminished using a mechanobiologically integrated implant with bone tissue. The purpose of this study was to investigate the biomechanical behavior, biocompatibility and bioactivity of a Ti-Nb-Sn alloy as a dental implant material. It was compared with cpTi. Cell proliferation and alkaline phosphatase (ALP) activity were quantified. To assess the degree of osseointegration, a push-in test was carried out. Cell proliferation and ALP activity in the cells grown on prepared surfaces were similar for the Ti-Nb-Sn alloy and for cpTi in all the experiments. A comparison between the Ti-Nb-Sn alloy implant and the cpTi implant revealed that no significant difference was apparent for the push-in test values. These results suggest that implants fabricated using Ti-Nb-Sn have a similar biological potential as cpTi and are capable of excellent osseointegration.

Osteoblastic differentiation of stromal ST-2 cells from octacalcium phosphate exposure via p38 signaling pathway.

The present study investigated the role of mitogen-activated protein kinase (MAPK) signaling in osteoblastic differentiation of stromal ST-2 cells induced by synthetic octacalcium phosphate (OCP) incubation. Since our previous studies revealed that OCP consumes calcium ions in media during conversion to hydroxyapatite, the effect of the ions on ST-2 cell differentiation with or without OCP crystals was analyzed. The effect of presence or absence of MAPK inhibitors was also analyzed. OCP increased alkaline phosphatase (ALP) activity and the mRNA expression of differentiation markers via the p38 signaling pathway. The PD98059 MAPK inhibitor increased ALP activity and differentiation marker genes in cells cultured in OCP-coated wells. Reduction of calcium ions in the medium by EGTA increased the ALP activity without OCP in the presence of phosphate ion concentrations up to 7.5 mM. OCP may enhance osteoblastic differentiation through the p38 signaling pathway via the reduction of calcium ions induced by its physicochemical property.