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Calcium Phosphate and Bioactive Glasses
Published in Vincenzo Guarino, Marco Antonio Alvarez-Pérez, Current Advances in Oral and Craniofacial Tissue Engineering, 2020
Osmar A. Chanes-Cuevas, José L. Barrera-Bernai, Iñigo Gaitán-S., David Masuoka
Bioglasses are mainly used in tissue bioengineering to promote bone regeneration by the ease with which they bind to the bone by forming a layer of hydroxyapatite substituted with carbonate or hydroxycarbonate apatite (HCA). There are three main types of bioglass that are, made of silicate, of phosphate and of borate, in addition to the combinations that occur between these and among other bioceramics (Rahaman et al. 2011; Fu et al. 2011; Jones 2015). Although the chemical mechanism by which the transformation of the bioglass into the HCA layer is well known, the process by which it joins the bone and favors the formation of new bone tissue is less studied. When placed in an organism, the bioglass will interact with physiological fluids, producing an ionic exchange that raises the pH of the medium, which dissolves the silicate and forms a silanol layer on which phosphate groups and calcium ions are added to form an amorphous calcium phosphate (APC), to which OH groups are attached, and CO, to finally form the HCA layer (Rahaman et al. 2011; Fu et al. 2011; Jones 2015). It is believed that the formed layer of HCA, as well as the ions released during its formation, has important roles in the regeneration of bone tissue, functioning as chemoattractants of stem cells and favoring their differentiation towards an osteoblastic phenotype.
Ultratrace Minerals
Published in Luke R. Bucci, Nutrition Applied to Injury Rehabilitation and Sports Medicine, 2020
Deficiencies of silicon have been linked to osteoporosis, osteoarthritis, atherosclerosis, and hypertension, but no firm connections have been documented.1076 The human requirement for silicon is estimated at 5 to 20 mg/d, which is at or below usual dietary intakes of approximately 31 mg/d.1043,1076 Richest food sources of silicon are unrefined grains with high fiber content, cereal products, root vegetables, and apples (pectin).1076 Animal foodstuffs have very low levels of silicon. Doubtless, humans that do not possess sanitary living conditions (unwashed, whole raw foods) derive a larger intake of silicon from dirt. Food silicon is mostly in the form of silicates, which is also the major form in blood and urine.1076 Oral consumption of silicates has proven to be nontoxic (at least for the silicate moiety) at high intake levels. Silicates are common antacids and food additives.
Bio-Ceramics for Tissue Engineering
Published in Naznin Sultana, Sanchita Bandyopadhyay-Ghosh, Chin Fhong Soon, Tissue Engineering Strategies for Organ Regeneration, 2020
Hasan Zuhudi Abdullah, Te Chuan Lee, Maizlinda Izwana Idris, Mohamad Ali Selimin
There are several types of bioactive glasses (BG) and these include silicate based-glasses, phosphate based-glasses and borate based – glasses (Jones 2015, Rahaman et al. 2011). Miguez-Pacheco et al. (2015) listed (Table 8.3) the formulations of several bioactive glasses (BG) which have been recently studied and investigated thoroughly (Jones 2015, Rahaman et al. 2011, Nandi et al. 2011, Hench 1998, Brink et al. 1997, Brown et al. 2008, Lindfors et al. 2010, Clare 2004, Detsch et al. 2014, Filgueiras et al. 1993). It can be seen that bioactive silicate-based glasses have been found to be a revolutionary material after trials, showing effective and successful adherence and bonding to human bone and tissue. Hench et al. (Hench et al. 1971, Hench 2006, 2015) designed Bioglass 45S5 with 45 wt. % silica (SiO2), 24.5 wt. % calcium oxide (CaO), 24.5 wt. % sodium oxide (Na2O) and 6 wt. % phosphorus pentoxide (P2O5) as shown in Fig. 8.8. These chemical combinations are categorized as Class A bioactivity owing to their outstanding osteoconductive and osteoproductive characteristics (Hench 2015). This is due to the ions released from BG reacted positively in biological solutions such as in simulated body fluid (SBF) and thus induced the formation of carbonated hydroxyapatite (HCA) layers on the surface of glass (Rezwan et al. 2006, Hoppe et al. 2011).
Toxicological and epidemiological approaches to carcinogenic potency modeling for mixed mineral fiber exposure: the case of fibrous balangeroite and chrysotile
Published in Inhalation Toxicology, 2023
Andrey A. Korchevskiy, Ann G. Wylie
Our study has significant uncertainties and limitations. The cancer potency models applied to balangeroite in this paper were developed for amphibole minerals and extrapolated to balangeroite, a mineral not belonging to the amphibole group. However, the results of our analysis demonstrate consistency in applying the amphibole model across different approaches to estimating carcinogenic potential. There are no data for airborne balangeroite fibers from the Balangero mine and the mine currently does not operate. Even if such records were available, without TEM analysis of air filters, an uncommon occurrence, the distinction between chrysotile and balangeroite would not have been made. It should be also noted that no lung burden data are available to assess the biodurability of balangeroite in human lungs. Our study, however, demonstrates that balangeroite should be more biopersistent in lungs than quickly dissolving chrysotile. It appears that balangeroite has a substantial carcinogenic potency as was initially suggested by Groppo et al. (2005). Public health measures to assess the risks further are warranted not only for balangeroite, but for other types of durable silicate fibers, and these should be the focus of epidemiological and toxicological studies in different regions of the world.
Antimicrobial effectiveness of root canal sealers against Enterococcus faecalis
Published in Biomaterial Investigations in Dentistry, 2022
Paola Castillo-Villagomez, Elizabeth Madla-Cruz, Fanny Lopez-Martinez, Idalia Rodriguez-Delgado, Jorge Jaime Flores-Treviño, Guadalupe Ismael Malagon-Santiago, Myriam Angelica de La Garza-Ramos
Complete removal of microorganisms from the root canal system in all patients is impossible; therefore, filling materials with antimicrobial activity for the root canal are used to reduce microorganisms and prevent infections. On the other hand, many endodontic failures occur after removing necrotic or inflammatory tissue with microorganisms. These tissues need to be retreated and managed with apical surgery; however, filtration failure occurs in 15% to 22% [4]. These complications are attributed to the lack of root canal sealing after endodontic treatment due to the high hydrophobicity and water absorption caused by the solubility of the cement. The development of new ceramic-type materials has improved sealing to reduce this problem. Epoxy resin is widely used as a gold standard, although it still has limitations, such as mutagenicity, cytotoxicity, inflammation, and hydrophobicity. Calcium silicate-based sealers with high biocompatibility and hydrophilicity have also been introduced. Both cements reduce microfiltration thanks to properties in their dynamic environment and being biocompatible in this application [5].
Microneedles for transdermal drug delivery using clay-based composites
Published in Expert Opinion on Drug Delivery, 2022
Farzaneh Sabbagh, Beom Soo Kim
A biocompatible and ion-exchangeable kind of clay can be a flexible carrier for a variety of drugs. Recently, layered silicate/polymer nanomaterials are gaining more recognition in fields such as regenerative medicine and drug delivery. Because of the economic benefits and low toxicity of clay, it is preferred as a delivery system and filler. Clay composites will be developed as targeted, prolonged, convenient, and efficient delivery systems with the ability to deliver lipophilic and hydrophilic pharmaceuticals. By controlling their nanoscale structures, clay effectiveness can be enhanced by using innovative synthesis, modification, insertion, and incorporation processes in matrices; these materials can then be used to control the release time of drugs. Polymer microneedles are of great interest in transdermal delivery microneedle therapy because these needles have several advantages including good mechanical properties and low cost. To gain market share in a highly competitive environment, the production cost of clay/polymer microneedles must remain low. Economical polymeric materials for microneedle production include polycaprolactone, polyglycolic acid, polylactic acid, and their copolymers; these materials have a long history of biocompatibility as resorbable sutures and show excellent strength. The various methods of microneedle fabrication include the hemispheric, magnetorheological drawing lithography, hot embossing, and solvent casting methods. According to the above discussion, more research and exploration are needed to make clay nanomaterials productive and economically available in the therapeutic industry.