3D printable magnesium-based cements towards the preparation of bioceramics

HYPOTHESIS

Among all the materials used so far to replace and repair damaged bone tissues, magnesium silicate bioceramics are one of the most promising, thanks to their biocompatibility, osteoinductive properties and good mechanical stability.

EXPERIMENTS

Magnesium silicate cement pastes were prepared by hydration of MgO mixed with different SiO₂ batches at different Mg/Si molar ratios. Pastes were either moulded or 3D printed to obtain set cements that were then calcined at 1000 °C to produce biologically relevant ceramic materials. Both cements and ceramics were characterized by means of X-ray diffraction, while two selected formulations were thoroughly characterized by means of injectability tests, Raman confocal microscopy, scanning electron microscopy, atomic force microscopy, gas porosimetry, X-ray microtomography and compressive tests.

FINDINGS

The results show that bioceramic scaffolds, namely forsterite and clinoenstatite, can be effectively obtained by 3D printing MgO/SiO₂ cement pastes, paving the way towards important advances in the field of bone tissue engineering.

Recent advances and future perspectives of sol–gel derived porous bioactive glasses: a review

Sol–gel derived bioactive glasses have been extensively explored as a promising and highly porous scaffold materials for bone tissue regeneration applications owing to their exceptional osteoconductivity, osteostimulation and degradation rates.

Importance of crosslinking strategies in designing smart biomaterials for bone tissue engineering: A systematic review

Biomaterials are of significant importance in biomedical applications as these biological macromolecules have moderately replaced classical tissue grafting techniques owing to its beneficial properties. Despite of its favourable advantages, poor mechanical and degradative properties of biomaterials are of great concern. To this regard, crosslinkers have emerged as a smart and promising tool to augment the biological functionality of biopolymers. Different crosslinkers have been extensively used in past decades to develop bone substitutes, but the implications of toxic response and adverse reactions are truly precarious after implantation. Traditional crosslinker like glutaraldehyde has been widely used in numerous bio-implants but the potential toxicity is largely being debated with many disproving views. As alternative, green chemicals, enzymatic and non-enzymatic chemicals, bi-functional epoxies, zero-length crosslinkers and physical crosslinkers have been introduced to achieve the desired properties of a bone substitute. In this review, systematic literature search was performed on PubMed database to identify the most commonly used crosslinkers for developing promising bone like materials. The relevant articles were identified, analysed and reviewed in this paper giving due importance to different crosslinking methodologies and comparing their effectiveness and efficacy in regard to material composition, scaffold production, crosslinker dosage, toxicity and immunogenicity. This review summarizes the recent developments in crosslinking mechanism with an emphasis placed on their ability to link proteins through bonding reactions. Finally, this study also covers the convergent and divergent methodologies of crosslinking strategies also giving special importance in retrieving the current limitations and future opportunities of crosslinking modalities in bone tissue engineering.

Sol-gel bioglasses in dental and periodontal regeneration: A systematic review

Due to their osteoconductive and osteoinductive abilities, bioglasses (BGs) have attracted attention in tissue engineering, especially for mineralized tissue. The aim of this study is to review the current state of the art on the effects of BGs produced by sol-gel on cells for dental and periodontal regeneration. The study also discusses associated antibacterial properties. The research was performed by considering the Preferred Reporting Items for Systematic Reviews and the Meta-Analyses (PRISMA) statement. The research ranged 5 years' window time (from January, 01, 2012, to August, 31, 2017) and the relevant studies were identified based on the inclusion/exclusion criteria. A total of 45 articles were selected from 244 initial returns, plus seven further articles coming from other sources were selected for the same purpose. From this systematic study, it is revealed that only 13 of the 52 articles have proved both the ability of BGs to differentiate dental cells at genetic level and their ability of triggering cell-mediated mineralization, but only six of them showed, along with cells, the antibacterial properties of the glasses. This review shows that sol-gel BGs are not toxic, can sustain cell proliferation and differentiation at a genetic level, and can keep the bacterial population under control. Moreover, a standard methodology and an ideal material are suggested. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1210-1227, 2019.