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Effects of Thermal Cycling on Surface Hardness, Diametral Tensile Strength and Porosity of an Organically Modified Ceramic (ORMOCER)-Based Visible Light Cure Dental Restorative Resin
Published in P. Mereena Luke, K. R. Dhanya, Didier Rouxel, Nandakumar Kalarikkal, Sabu Thomas, Advanced Studies in Experimental and Clinical Medicine, 2021
ORMOCERS are very promising materials. Although ORMOCERS are very promising, few investigations [6] have confirmed the potential of ORMOCERS as biomaterials or low-contraction materials applied to teeth restoration. The two composites (Definite® (Degussa AG, Hanau, Germany) or Admira® (Voco GmbH, Cuxhaven, Germany) available in the market based on ORMOCER technology. Admira composite contained 78% inorganic particles (barium and aluminum silicate) with an average size of 0.7 μ and the organic fraction composed of 65.5%, conventional organic dimethacrylates such as BisGMA, and UDMA along with 34.5% of triethylene glycol dimethacrylate (TEGDMA). The concept of ORMOCER [7] is to combine properties of organic polymers with glass-like materials to generate new/synergistic properties. The processing steps are based on sol-gel type reaction. Our previous studies reported [8–12] the development of a noncytotoxic and biocompatible organically modified ceramic composite with lower polymerization shrinkage compared to a composite containing BisGMA.
Novel strategies for the enhancement of zirconia behavior
Published in R.M. Natal Jorge, J.C. Reis Campos, Mário A.P. Vaz, Sónia M. Santos, João Manuel R.S. Tavares, Biodental Engineering IV, 2017
R.S.F. Pereira, B. Henriques, M.C. Fredel, F.S. Silva
Yttria fully stabilized microstructure modification, using precipitates as alumina, to obtain small microstructural grains and, as a consequence, ceramic-ceramic composite materials. This approach was mainly used to improve mechanical properties of hip implants, with the drawback, for oral applications, of increasing the Young’s Modulus of the composite (Tebaldo & Gautier 2013; Perrichon et al. 2016; Nevarez-Rascon et al. 2009).
Bioceramic Nanoparticles for Tissue Engineering
Published in Harishkumar Madhyastha, Durgesh Nandini Chauhan, Nanopharmaceuticals in Regenerative Medicine, 2022
The initial applications of both of these ceramics in total joint replacement was found to be associated with certain limitations (Thamaraiselvi and Rajeswari 2003, Roualdes et al. 2010). High fracture rates were found in the case of alumina, whereas zirconia was found to be unstable and get transformed catastrophically into the monoclinic phase, depending on its manufacturing conditions and hydrothermal effects in vivo (Kurtz et al. 2014). To address these clinical problems, the development of mixed oxides ceramic materials known as “composite” materials represents a major new advancement of clinically available orthopaedic biomaterials. Ceramic composites act synergistically to give properties, better than those provided by either component alone and also, enjoy the superiority due to similarity with bone minerals (Thamaraiselvi and Rajeswari 2003). Two types of composites known as zirconia-toughened alumina (ZTA), in which alumina matrix is embedded with zirconia particles, and alumina-toughened zirconia (ATZ) where zirconia matrix is dispersed with particles of alumina, exhibiting superior strength and toughness, can be fabricated from mixtures of alumina and zirconia (Affatato et al. 2006). The concerns related to hydrothermal firmness still persist in the case of ATZ (Affatato et al. 2006). The properties such as high strength, toughness, hardness, wear resistance, and low susceptibility of stress-assisted degradation of alumina make ZTA increasingly important as a structural material for orthopaedic applications (Kurtz et al. 2014) (Affatato et al. 2006). All these properties of the ZTA reduce the risk of dislocation and impingement and enhance the stability of implants. However, the magnitude of all these mechanical as well as biological properties is completely dependent on the different processing routes proposed for ZTA composites. Affatato et al. (Affatato et al. 2006) reported the development of high-density ZTA nanocomposites with superior properties such as very homogenous microstructure, high crack resistance, increased fracture toughness, and hydrothermal stability. Further, they observed no significant differences between the wear behaviours and osteoblast growth onto nanocomposite samples of ZTA in comparison with commercial alumina and experimental alumina specimens. In another study by Roualdes et al. (Roualdes et al. 2010), the in vitro and in vivo biocompatibility of a ceramic composite composed of alumina-zirconia, processed by a standard powder-mixing technique, was investigated. The results showed that in vitro, the ZTA composite resulted in no deleterious effects on cell growth and its phenotypical features, and extra-cellular matrix production by fibroblasts and osteoblast cultured upon sintered ceramic discs and in the presence of submicron-sized alumina or zirconia particles at various dose concentrations. A very normal and non-specific response of the synovial membrane leading to the formation of granulomatous tissue, but no major pain or inflammation was observed at local or systemic site in Sprague Dawley rats after intra-articular injection of ZTA particulates.
Effect of interfacial surface treatment on bond strength of particulate-filled composite to short fiber-reinforced composite
Published in Biomaterial Investigations in Dentistry, 2022
L. Lassila, J. Tuokko, A. Suni, S. Garoushi, P. K. Vallittu
Direct composite restoration, also known as particulate-filled composite (PFC) restoration, is a common restorative procedure for treating lost tooth structure. It has been reported that general dental practitioners in public dental facilities spend more than half their time applying direct composite restorations [1]. Aside from the capability to adhere to tooth structures via bonding systems, direct PFC composite restorations are less expensive than indirect ceramic/composite restorations [2]. The application of direct PFC composites has expanded to include not just posterior intra-coronal restorations, but also extra-coronal restorations [2]. Nevertheless, mechanical properties and polymerization shrinkage are still issues with contemporary PFCs. In small and medium-sized cavities, PFC restorations have shown satisfactory overall clinical performance, with annual failure rates ranging from 1 to 3 percent [3,4]. However, the clinical performance of PFC restorations is clearly associated with restoration size. Large PFC restorations have proven to be more likely to fail due to fractures, resulting in shorter lifespans [3,4].
An update of interbody cages for spine fusion surgeries: from shape design to materials
Published in Expert Review of Medical Devices, 2022
Guangshen Li, Lei Yang, Gang Wu, Zhanyang Qian, Haijun Li
Human bone can be regarded as a kind of natural nanostructured ceramic composite, which is mainly composed of a calcium phosphate compound, called hydroxyapatite (HA), and type I collagen [94].HA is also a kind of tissue engineering material, which has good biocompatibility and bone conductivity and can be absorbed, but it has poor biomechanical properties and low maneuverability, so it can promote fusion, but it cannot be directly applied and can only assist other materials.