Bone grafts and biomaterials substitutes for bone defect repair: A review.

https://www.journalofprosthodonticresearch.com/article/S1883-1958(15)00099-7/pdf

Applications of polyetheretherketone (PEEK) in oral implantology and prosthodontics

It is of great importance to develop multifunctional bioactive scaffolds, which combine angiogenesis capacity, osteostimulation, and antibacterial properties for regenerating lost bone tissues. In order to achieve this aim, we prepared copper (Cu)-containing mesoporous bioactive glass (Cu-MBG) scaffolds with interconnective large pores (several hundred micrometer) and well-ordered mesopore channels (around 5 nm). Both Cu-MBG scaffolds and their ionic extracts could stimulate hypoxia-inducible factor (HIF)-1a and vascular endothelial growth factor(VEGF) expression in human bone marrow stromal cells(hBMSCs). In addition, both Cu-MBG scaffolds and their ionic extracts significantly promoted the osteogenic differentiation of hBMSCs by improving their bone-related gene expression (alkaline phosphatase (ALP), osteopontin(OPN) and osteocalcin (OCN)). Furthermore, Cu-MBG scaffolds could maintain a sustained release of ibuprofen and significantly inhibited the viability of bacteria. This study indicates that the incorporation of Cu2þ ions into MBG scaffolds significantly enhances hypoxia-like tissue reaction leading to the coupling of angiogenesis and osteogenesis. Cu2þ ions play an important role to offer the multifunctional properties of MBG scaffold system. This study has demonstrated that it is possible to develop multifunctional scaffolds by combining enhanced angiogenesis potential, osteostimulation, and antibacterial properties for the treatment of large bone defects.

Copper-containing mesoporous bioactive glass scaffolds with multifunctional properties of angiogenesis capacity, osteostimulation and antibacterial activity

Additive manufacturing of biomaterials.

The synthetic thermoplastic polymer polyetheretherketone (PEEK) is becoming a popular component of clinical orthopedic and spinal applications, but its practical use suffers from several limitations. Although PEEK is biocompatible, chemically stable, radiolucent and has an elastic modulus similar to that of normal human bone, it is biologically inert, preventing good integration with adjacent bone tissues upon implantation. Recent efforts have focused on increasing the bioactivity of PEEK to improve the bone-implant interface. Two main strategies have been used to overcome the inert character of PEEK. One approach is surface modification to activate PEEK through surface treatment alone or in combination with a surface coating. Another strategy is to prepare bioactive PEEK composites by impregnating bioactive materials into PEEK substrate. Researchers believe that modified bioactive PEEK will have a wide range of orthopedic applications.

https://www.mdpi.com/1422-0067/15/4/5426/pdf

Current strategies to improve the bioactivity of PEEK

Cytocompatibility, osseointegration, and bioactivity of three-dimensional porous and nanostructured network on polyetheretherketone.

A newly developed copper-bearing stainless steel (Cu-SS) by directly immobilizing proper amount of Cu into a medical stainless steel (317L SS) during the metallurgical process could enable continuous release of trace amount of Cu2+ ions, which play the key role to offer the multibiofunctions of the stainless steel, including the osteogenic ability in the present study. The results of in vitro experiments clearly demonstrated that Cu2+ ions from Cu-SS could promote the osteogenic differentiation by stimulating the Alkaline phosphatase enzyme activity and the osteogenic gene expressions (Col1a1, Opn, and Runx2), and enhancing the adhesion and proliferation of osteoblasts cultured on its surface. The in vivo test further proved that more new bone tissue formed around the Cu-SS implant with more stable bone-to-implant contact in comparison with the 317L SS. In addition, Cu-SS showed satisfied bio- compatibility according to the results of in vitro cytotoxicity and in vivo histocompatibility, and its daily released amount of Cu2- ions in physiological saline solution was at trace level of ppb order (1.4 ppb/cm(2)), which is rather safe to human health. Apart from these results, it was also found that Cu-SS could inhibit the happening of inflammation with lower TNF-(x expression in the bone tissue post implantation compared with 317L SS. In addition to good biocompatibility, the overall findings demonstrated that the Cu-SS possessed obvious ability of promoting osteogenesis, indicating a unique application advantage in orthopedics. (C) 2014 Wiley Periodicals, Inc. J Blamed Mater Res Part B: Appl Biomater, 103B: 1433-1444,2015.

Osteogenic ability of Cu‐bearing stainless steel

In this study, a Mo-bearing high–Si austenitic stainless steel was designed for lead-cooled fast reactor, and the precipitation behavior and mechanical properties of the experimental steel after 650 °C isothermal aging for 3000 h were investigated. The results showed that Mo-enriched χ phase was revealed to preferentially precipitate not only at grain boundaries, but also on the nano-sized secondary MC particles during long-term aging. The secondary MC carbides acted as nucleation sites of χ phase particles, leading to lenticular shape composite precipitates. Si can improve the precipitation driving force and was discovered to segregate in the χ phase, which indicates that Si can accelerate the formation of χ phase during aging. The precipitation of the χ phase dramatically reduced the plasticity and toughness of the steel, but did less harm to the strength. 

Chun Hoi Yan

Papers

Cytocompatibility, osseointegration, and bioactivity of three-dimensional porous and nanostructured network on polyetheretherketone.

Osteogenic ability of Cu‐bearing stainless steel

χ phase and its effect on the mechanical properties of a Mo-bearing high–Si austenitic stainless steel after aging at 650 °C

Effect of thermal aging at 550 °C on microstructure and mechanical properties of a 9Cr martensitic steel with high silicon content