Zirconia (ZrO2) based dental ceramics have been considered to be advantageous materials with adequate mechanical properties for the manufacturing of medical devices. Due to its very high compression strength of 2000 MPa, ZrO2 can resist differing mechanical environments. During the crack propagation on the application of stress on the surface of ZrO2, a crystalline modification diminishes the propagation of cracks. In addition, zirconia's biocompatibility has been studied in vivo, leading to the observation of no adverse response upon the insertion of ZrO2 samples into the bone or muscle. In vitro experimentation has exhibited the absence of mutations and good viability of cells cultured on this material leading to the use of ZrO2 in the manufacturing of hip head prostheses. The mechanical properties of zirconia fixed partial dentures (FPDs) have proven to be superior to other ceramic/composite restorations and hence leading to their significant applications in implant supported rehabilitations. Recent developments were focused on the synthesis of zirconia based dental materials. More recently, zirconia has been introduced in prosthetic dentistry for the fabrication of crowns and fixed partial dentures in combination with computer aided design/computer aided manufacturing (CAD/CAM) techniques. This systematic review covers the results of past as well as recent scientific studies on the properties of zirconia based ceramics such as their specific compositions, microstructures, mechanical strength, biocompatibility and other applications in dentistry.

Zirconia based dental ceramics: structure, mechanical properties, biocompatibility and applications.

With the rapid development of nanoscience and nanotechnology over the last decades, great progress has been made not only in the preparation and characterization of nanomaterials, but also in their functional applications. As an important one-dimensional nanomaterial, nanofibers have extremely high specific surface area because of their small diameters, and nanofiber membranes are highly porous with excellent pore interconnectivity. These unique characteristics plus the functionalities from the materials themselves impart nanofibers with a number of novel properties for applications in areas as various as biomedical engineering, wound healing, drug delivery and release control, catalyst and enzyme carriers, filtration, environment protection, composite reinforcement, sensors, optics, energy harvest and storage , and many others. More and more emphasis has recently been placed on large-scale nanofiber production, the key technology to the wide usages of nanofibers in practice. Tremendous efforts have been made on producing nanofibers from special materials. Concerns have been raised to the safety issue of nanofibrous materials. This book is a compilation of contributions made by experts who specialize in their chosen field. It is grouped into three sections composed of twenty-one chapters, providing an up-to-date coverage of nanofiber preparation, properties and functional applications. I am deeply appreciative of all the authors and have no doubt that their contribution will be a useful resource of anyone associated with the discipline of nanofibers.

Nanofibers - production, properties and functional applications

Fully dense yttria-stabilized zirconia (YSZ) ceramics reinforced with reduced graphene oxide (RGO) were fabricated by spark plasma sintering (SPS), and their electrical, thermal, and mechanical properties were investigated. Graphene oxide (GO) was exfoliated by a short sonification in dimethylformamide (DMF)/water solution and uniformly mixed with ZrO2 powders. The microstructure of the composites showed that undamaged RGO sheets were homogeneously distributed throughout matrix grains. The electrical conductivity of YSZ composites drastically increased with the addition of RGO, and it reached 1.2 × 104 S/m at 4.1 vol.%. However, the thermal diffusivity increased only 12% with RGO addition. The hardness decreased slightly with RGO addition, whereas the fracture toughness significantly increased from 4.4 to 5.9 MPa1/2. The RGO pull-out and crack bridging contributed to the improved fracture toughness.

Fabrication and properties of reduced graphene oxide reinforced yttria-stabilized zirconia composite ceramics

https://iopscience.iop.org/article/10.1088/1468-6996/16/3/033504/pdf

Tangible nanocomposites with diverse properties for heart valve application.

This review paper reported carbon nanotubes reinforced composites for biomedical applications Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites), their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo

https://downloads.hindawi.com/journals/bmri/2014/518609.pdf

Carbon nanotubes reinforced composites for biomedical applications.

Zirconia ceramics are widely used as femoral heads, but case studies show that delayed failure can occur in vivo due to crack propagation. The addition of carbon nanotubes (CNT) is aimed to avoid the slow crack propagation and to enhance the toughness of the ceramic material used for prostheses. However, to really enhance the mechanical properties of the material it is necessary to achieve a uniform distribution of the CNT in the zirconia matrix. Colloidal processing has demonstrated to be suitable for obtaining ceramic-based composites with homogeneous distribution of the phases and high green density. This work compares the colloidal behavior of the as-received multi wall carbon nanotubes (ar-MWCNT) and the partially coated MWCNT (pc-MWCNT) when immersed in a nanozirconia matrix. With pc-MWCNT an improvement in the dispersion is proved. Moreover, the sintered samples that contain pc-MWCNT show higher density, lower grain size, improved toughness and enhanced hardness under the same sintering cycle when compared to the samples with ar-MWCNT.

I. Obieta

Papers

Zirconia-MWCNT nanocomposites for biomedical applications obtained by colloidal processing