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1.
The importance of being amorphous: calcium and magnesium phosphates in the human body.
Gelli, R, Ridi, F, Baglioni, P
Advances in colloid and interface science. 2019;:219-235
Abstract
This article focuses on the relevance of amorphous calcium (and magnesium) phosphates in living organisms. Although crystalline calcium phosphate (CaP)-based materials are known to constitute the major inorganic constituents of human hard tissues, amorphous CaP-based structures, often in combination with magnesium, are frequently employed by Nature to build up components of our body and guarantee their proper functioning. After a brief description of amorphous calcium phosphate (ACP) formation mechanism and structure, this paper is focused on the stabilization strategies that can be used to enhance the lifetime of the poorly stable amorphous phase. The various locations of our body in which ACP (pure or in combination with Mg2+) can be found (i.e. bone, enamel, small intestine, calciprotein particles and casein micelles) are highlighted, showing how the amorphous nature of ACP is often of paramount importance for the achievement of a specific physiological function. The last section is devoted to ACP-based biomaterials, focusing on how these materials differ from their crystalline counterparts in terms of biological response.
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2.
Systematic review of current dental implant coating materials and novel coating techniques.
Xuereb, M, Camilleri, J, Attard, NJ
The International journal of prosthodontics. 2015;(1):51-9
Abstract
PURPOSE Titanium dental implants have a high success rate; however, there are instances when a modified surface may be desirable. The aim of this article was to systematically review the different types of implant coatings that have been studied clinically, in vivo and in vitro, and the coating techniques being implemented. MATERIALS AND METHODS The literature was searched electronically and manually through The Cochrane Library, Medline, and PubMed databases to identify articles studying dental implant surfaces and coating techniques. The database search strategy revealed 320 articles, of which 52 articles were considered eligible--40 in relation to implant coatings and 12 to the coating technique. An additional 30 articles were retrieved by hand search. RESULTS Several materials were identified as possible candidates for dental implant coatings; these include carbon, bisphosphonates, bone stimulating factors, bioactive glass and bioactive ceramics, fluoride, hydroxyapatite (HA) and calcium phosphate, and titanium/titanium nitride. HA coatings still remain the most biocompatible coatings even though the more innovative bioglass suggests promising results. The most common coating techniques are plasma spraying and hydrocoating. More recent techniques such as the nanoscale technology are also discussed. CONCLUSIONS Several implant coatings have been proposed, and some appear to give better clinical results and improved properties than others. Clinical trials are still required to provide compelling evidence-based results for their long-term successful outcomes.
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3.
Biomaterials in Relation to Dentistry.
Deb, S, Chana, S
Frontiers of oral biology. 2015;:1-12
Abstract
Dental caries remains a challenge in the improvement of oral health. It is the most common and widespread biofilm-dependent oral disease, resulting in the destruction of tooth structure by the acidic attack from cariogenic bacteria. The tooth is a heavily mineralised tissue, and both enamel and dentine can undergo demineralisation due to trauma or dietary conditions. The adult population worldwide affected by dental caries is enormous and despite significant advances in caries prevention and tooth restoration, treatments continue to pose a substantial burden to healthcare. Biomaterials play a vital role in the restoration of the diseased or damaged tooth structure and, despite providing reasonable outcomes, there are some concerns with clinical performance. Amalgam, the silver grey biomaterial that has been widely used as a restorative material in dentistry, is currently in throes of being phased out, especially with the Minimata convention and treaty being signed by a number of countries (January 2013; http://mercuryconvention.org/Convention/) that aims to control the anthropogenic release of mercury in the environment, which naturally impacts the use of amalgam, where mercury is a component. Thus, the development of alternative restoratives and restoration methods that are inexpensive, can be used under different climatic conditions, withstand storage and allow easy handling, the main prerequisites of dental biomaterials, is important. The potential for using biologically engineered tissue and consequent research to replace damaged tissues has also seen a quantum leap in the last decade. Ongoing research in regenerative treatments in dentistry includes alveolar ridge augmentation, bone tissue engineering and periodontal ligament replacement, and a future aim is bioengineering of the whole tooth. Research towards developing bioengineered teeth is well underway and identification of adult stem cell sources to make this a viable treatment is advancing; however, this topic is not in the scope of this chapter. Whilst research focuses on many different aspects, operative dentistry involves the wide use of restorative biomaterials; thus, the development of smart biomaterials to suit the current climes of minimally invasive dentistry is important. The concept of minimally invasive dentistry primarily promotes preservation of the natural tissue, and, thus, the prevention of disease or the advancement of procedures that allow early detection and interception of its progress with minimal tissue loss are of significance. This chapter presents, in brief, the current state of the art of direct restorative biomaterials and their role and future in the field of dentistry. Modern dental practice is highly reliant on the selection of appropriate materials for optimum function and benefit to the patient. Dentistry, perhaps, has the unique distinction of using the widest variety of materials, ranging from polymers, metals, ceramics, inorganic salts to composite materials. So far, aesthetics of restorative materials and their ability to perform in the harsh oral environment without undergoing changes in dimension and stability has been the major focus of materials used in dentistry. Despite advances in tissue engineering and regeneration in the field of regenerative medicine, this concept has found relatively limited application for enamel and dentine due to their limited ability to remodel, but research related to biomimetic approaches for the modification of dentine is a significant step.
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4.
Gene Expression Profiling and Molecular Signaling of Dental Pulp Cells in Response to Tricalcium Silicate Cements: A Systematic Review.
Rathinam, E, Rajasekharan, S, Chitturi, RT, Martens, L, De Coster, P
Journal of endodontics. 2015;(11):1805-17
Abstract
INTRODUCTION Signaling molecules and responding dental pulp stem cells are the 2 main control keys of dentin regeneration/dentinogenesis. The aim of this study was to present a systematic review investigating the gene expression of various dental pulp cells in response to different variants of tricalcium silicate cements. METHODS A systematic search of the literature was performed by 2 independent reviewers followed by article selection and data extraction. Studies analyzing all sorts of dental pulp cells (DPCs) and any variant of tricalcium silicate cement either as the experimental or as the control group were included. RESULTS A total of 39 articles were included in the review. Among the included studies, ProRoot MTA (Dentsply, Tulsa Dental, OK) was the most commonly used tricalcium silicate cement variant. The extracellular signal regulated kinase/mitogen-activated protein kinase pathway was the most commonly activated pathway to be identified, and similarly, dentin sialophosphoprotein osteocalcin dentin matrix acidic phosphoprotein 1, alkaline phosphatase, bone sialoprotein, osteopontin, type I collagen, and Runx2 were the most commonly expressed genes in that order of frequency. CONCLUSIONS Biodentine (Septodont Ltd, Saint Maur des Faussés, France), Bioaggregate (Innovative Bioceramix, Vancouver, BC, Canada), and mineral trioxide aggregate stimulate the osteogenic/odontogenic capacity of DPCs by proliferation, angiogenesis, and biomineralization through the activation of the extracellular signal regulated kinase ½, nuclear factor E2 related factor 2, p38, c-Jun N-terminal kinase mitogen-activated protein kinase, p42/p44 mitogen-activated protein kinase, nuclear factor kappa B, and fibroblast growth factor receptor pathways. When DPCs are placed into direct contact with tricalcium silicate cements, they show higher levels of gene activation, which in turn could translate into more effective pulpal repair and faster and more predictable formation of reparative dentin.
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5.
Cellular responses to metal ions released from implants.
Kardos, TB
The Journal of oral implantology. 2014;(3):294-8
Abstract
In the process of calcified tissue formation, cells secrete a protein-rich matrix into which they add a metal ion that nucleates in the presence of phosphorus to form an inorganic salt (usually calcium hydroxyapatite). Cellular and tissue responses to metal ions-released from implants, for example-can therefore be considered from the perspective of how cells handle calcium ions. A critical factor in determining cellular toxicity will be free ion concentrations and the competitive interactions that occur in a physicochemical manner. Three of the parameters used to assess the biocompatibility of implant materials are (1) the ability to influence mitotic activity, (2) intercellular adhesion, and (3) promotion of cell death. A spectrum of responses to free intracellular calcium ions can be identified, ranging from presence of the ion being essential for cell division through to an excess of the free ion that results in cell death (apoptosis). In between these extremes, cells may become postmitotic and express phenotypic variations as they adapt to their environment and establish equilibrium to maintain intracellular calcium homeostasis. The response of cells to implants can be linked to ions released and interactions between these and other ions and/or molecules present in the tissues, similar to the manner in which cells handle calcium ions.
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6.
Comparison of fracture resistance between cast posts and fiber posts: a meta-analysis of literature.
Zhou, L, Wang, Q
Journal of endodontics. 2013;(1):11-5
Abstract
INTRODUCTION The aim of this study was to compare the fracture resistance of cast posts versus the fracture resistance of fiber posts by means of meta-analysis when they were used in the restoration of endodontically treated teeth. METHODS MEDLINE, Cochrane Controlled Trials Register, China National Knowledge Infrastructure, and China Biology Medicine disc were used in the literature search. Two independent reviewers assessed the titles and abstracts of all articles that were found according to the predefined inclusion criteria. Relevant articles were acquired in full-text form. Data in these studies were independently extracted. Standardized mean differences of included studies were combined and analyzed by using meta-analysis. RESULTS Thirteen studies met the inclusion criteria. There was considerable heterogeneity among these studies. The standardized mean difference of the combined data was 0.64 (95% confidence interval, 0.08-1.20; P < .001), indicating that the cast post group displayed significantly higher fracture resistance than the fiber post group. CONCLUSIONS On the basis of the current best available evidence, we concluded that cast posts had higher fracture resistance than fiber posts.
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7.
[Improving cytotoxicity of resin-base materials by N-Acetylcysteine].
Huang, XQ, Huang, C, Sun, HL
Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology. 2011;(5):315-7
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8.
Update on dental nanocomposites.
Chen, MH
Journal of dental research. 2010;(6):549-60
Abstract
Dental resin-composites are comprised of a photo-polymerizable organic resin matrix and mixed with silane-treated reinforcing inorganic fillers. In the development of the composites, the three main components can be modified: the inorganic fillers, the organic resin matrix, and the silane coupling agents. The aim of this article is to review recent studies of the development of dental nanocomposites and their clinical applications. In nanocomposites, nanofillers are added and distributed in a dispersed form or as clusters. For increasing the mineral content of the tooth, calcium and phosphate ion-releasing composites and fluoride-releasing nanocomposites were developed by the addition of DCPA-whiskers or TTCP-whiskers or by the use of calcium fluoride or kaolinite. For enhancing mechanical properties, nanocomposites reinforced with nanofibers or nanoparticles were investigated. For reducing polymerization shrinkage, investigators modified the resin matrix by using methacrylate and epoxy functionalized nanocomposites based on silsesquioxane cores or epoxy-resin-based nanocomposites. The effects of silanization were also studied. Clinical consideration of light-curing modes and mechanical properties of nanocomposites, especially strength durability after immersion, was also addressed.
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9.
Can interaction of materials with the dentin-pulp complex contribute to dentin regeneration?
Ferracane, JL, Cooper, PR, Smith, AJ
Odontology. 2010;(1):2-14
Abstract
Understanding outcomes of the interaction between a dental material and tooth tissue is important in terms not only of biocompatibility but also of the potential for the material to modulate the response of the tissue. This interaction is influenced by many factors, including the chemistry of the material and any of its eluted components or degradation products, and the manner in which the tissue responds to these agents. Past studies of this interaction have primarily been aimed at identifying cytotoxic effects. More recently, investigations have focused on specific cellular responses, and in particular, on understanding how the materials themselves actually may contribute to regenerative processes in the tooth. Recent work has demonstrated the solubilization of proteins from dentin exposed to certain materials, such as calcium hydroxide, mineral trioxide aggregate, and acidic solutions that relate to those used in dentin bonding agents, with the subsequent modulation by these proteins of gene expression in odontoblast-like cells. This work suggests that dentin bridge formation under such materials may be stimulated through this process. Thus, there is much merit in examining both how new dental materials can be developed and how more traditional ones can be modified to preferentially stimulate regenerative processes when preferred. This review summarizes current knowledge about the potential beneficial effects derived from the interaction of dental materials with the dentin-pulp complex, as well as potential future developments in this exciting field.
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10.
Implant surface treatment using biomimetic agents.
Avila, G, Misch, K, Galindo-Moreno, P, Wang, HL
Implant dentistry. 2009;(1):17-26
Abstract
With an attempt at achieving faster osseointegration to hasten the overall treatment process, the use of biomimetic agents represents a growing area of research in implant dentistry. This study outlines 4 categories of bioactive agents that may be applied to coat the titanium implant surface: (1) biocompatible ceramics, (2) bioactive proteins, (3) ions, and (4) polymers, and their respective importance in the early stages of osseointegration. The potential bioactive agents investigated include bone morphogenetic proteins, growth factors, type I collagen, RGD peptide, fluoride, or chitosan, among others. The ideal characteristics that biomimetic agents should uphold and factors that may influence their effectiveness are reviewed. They include implant surface texture, time-oriented delivery vehicle and the ability of the agent to reach a target. Some of these agents, such as bioceramics (calcium phosphate salts) or ions (fluoride) are already commercially available and have shown clinical success. Others such as bone morphogenetic proteins are very promising, with an excellent therapeutic potential. A specific implant surface coating may enhance the percentage of bone-to-implant contact as well as speed of osseointegration that allows clinicians to overcome many challenging clinical scenarios.