Calcium Phosphate Materials Research Articles

Comparative Study of Calcium Phosphate versus Formocresol in Pulp Treatment of Primary Teeth

:Purpose: Clinical and radiographic evaluation of the postoperative success of Calcium Phosphate and formocreosl (FC) materials in pulpotomy treatment of primary teeth. Materials and Method: 75 Primary molars in 25 patients were chosen according to specific criteria. Teeth were devided depending on the pulpotomy material into 3 groups: Group I (Calcium phosphate with physiologic saline cleansing group), Group II (Calcium phosphate with Sodium hypochlorite) and GroupIII (formcresol group). This was followed by clinical follow up after 1, 6 months and a year. In addition, Periapical radiographs were collected post-operatively, 6 and 12 months visits. Results: Despite decreasing with time, the results showed no statistically significant difference in the cumulative clinical success between all three groups on the study period. Also, Radiographic success had a similar pattern over a year with no significant difference between groups. Conclusion: Calcium Phosphate as a pulpotomy material was observed to be a valuable alternative to regularly used formocresol with greater biocompatibility, mouldability, and osteoconductivity.

Electric characteristics of calcium-phosphate ceramics with impurities

The electrical characteristics of calcium phosphate materials have been studied at various frequencies in the temperature interval from room temperature to 1200 °C. It has been shown that the electrical characteristics (relative permittivity, capacitance, and electric resistance) change with the annealing temperature. Temperature changes in these characteristics are associated with the presence of impurities in the studied samples, as well as the nonstoichiometry of the phase composition of the initial samples. The phase composition and structure of the studied samples were studied by X-ray diffraction, Mass-spectrometry, and IR-spectroscopy. It has been shown that the studied calcium-phosphate samples have dielectric properties. The temperature intervals for the stability of the electrical characteristics of these materials have been established.

A novel rapidly mineralized biphasic calcium phosphate with high acid-resistance stability for long-term treatment of dentin hypersensitivity.

Treating dental hypersensitivity (DH) rapidly and maintaining long-term effectiveness remains challenging. We aimed to address this problem by fabricating a novel rapidly mineralized biphasic calcium phosphate (RMBCP), which could rapidly elicit mineralization to form hydroxyapatite (HA) and perform excellent acid-resistant stability, thus effectively blocking the exposed dental tubules and protecting them from acid attack. RMBCP was firstly synthesized by precisely adjusting the molar ratio of acetic acid and calcium hydroxide and characterized by X-ray diffraction (XRD), X-ray fluorescence microprobe (XRF), Fourier-transform infrared (FTIR) spectrometer, scanning electron microscope (SEM), and transmission electron microscope (TEM). Subsequently, using a commercialized desensitizing agent, 45S5 bioglass (BG), as the control group, the mineralization performance of RMBCP was investigated in simulated body fluid (SBF), Dulbecco's modified eagle medium (DMEM), and even slightly acidic artificial saliva (pH=6.6). Moreover, the biocompatibility of RMBCP was studied. Finally, the tubule occlusion effect and acid-resistant stability of RMBCP were evaluated in vitro and in vivo. The rapid mineralization behavior of RMBCP could easily adhere to the dentin surface and block the dentinal tubules completely in vitro and in vivo within 7days. RMBCP performed high acid-resistant stability to maintain the long-term therapeutic effect of DH treatment. Developing novel bioactive calcium phosphate materials with the ability to trigger mineralization for HA formation rapidly will be an effective strategy for the long-term treatment of dentin hypersensitivity.

Zn-doped Mono- and Biphasic Calcium Phosphate Materials Derived from Agriculture Waste and Their Potential Biomedical Applications: Part I.

In this study, calcium phosphate materials were obtained via a simple, eco-friendly wet synthesis method using hen eggshells as a calcium source. It was shown that Zn ions were successfully incorporated into hydroxyapatite (HA). The obtained ceramic composition depends on the zinc content. When doped with 10 mol % of Zn, in addition to HA and Zn-doped HA, DCPD (dicalcium phosphate dihydrate) appeared and its content increased with the increase in Zn concentration. All doped HA materials exhibited antimicrobial activity against S. aureus and E. coli. Nevertheless, fabricated samples significantly decreased preosteoblast (MC3T3-E1 Subclone 4) viability in vitro, exerting a cytotoxic effect which probably resulted from their high ionic reactivity.

Mechanical processing of hydroxyapatite through sintering and multi-objective optimization technique for biomedical application

Hydroxyapatite (HAp) has been widely applied in the area of tissue engineering, however, its poor mechanical properties limit it in load bearing biomedical application. To improve the mechanical integrity of HAp, this study reports the synthesis, optimization and the significance of processing parameters on the physic-mechanical properties of HAp. The HAp was produced from biogenic source through at 900 °C. The L9 Taguchi orthogonal array was employed, considering two processing parameters namely, HAp particle size (100, 300, and 600 mathrm{mu m}) and compaction load (3, 6, and 9 KN). The raw bones (RB) and the synthesized HAp were characterized for phase structure and functional groups analysis. The analysis showed the characteristics of a typical calcium phosphate material. The multiple response optimization revealed that 600 mathrm{mu m} particle size 6 KN compaction load are the optimal processing parameters in the manufacturing of high biomedical performance HAp.Graphical

Application of Calcium Phosphate Materials in Dentistry: A Review

Calcium phosphate materials are similar to bone in composition and having bioactive and osteoconductive properties. They have different forms, as cements, composites and coatings, which are used in many dental applications. This article reviews the latest update of their applications in dentistry the studies of improving the mechanical properties of these materials. Notable research is highlighted, regarding application of calcium phosphate into various fields in dentistry and improvement of their mechanical properties. This article deals with most common types of these materials including, calcium phosphate, hydroxyapatite and tricalcium phosphate. 
 Keywords: Calcium phosphate materials, Dentistry, Hydroxyapatite, Tricalcium phosphate

Calcium phosphate with submicron topography influences primary human macrophage response, enhancing downstream angiogenesis and osteogenesis in vitro

Calcium phosphates with submicron surface features have demonstrated superior performance to conventional calcium phosphates and equivalence to autologous bone in pre-clinical bone healing models. This is related to their ability to form bone in soft tissues, without the addition of cells and growth factors. It is hypothesized that a specific innate immune response to submicron topography contributes to the enhanced bone healing by these materials. Upregulation of pro-healing, anti-inflammatory ‘M2’ macrophages versus pro-inflammatory ‘M1’ macrophages on submicron-structured calcium phosphates may be involved. In this in vitro study, the response of primary human macrophages to different calcium phosphate bone graft substitutes was assessed. Primary CD14+ monocytes were isolated from human buffy coats and were seeded on two different calcium phosphate materials. The first material had a submicron topography of needle-shaped crystals (BCP<μm) while the second material had no submicron topography (TCP). Macrophage M1/M2 phenotype characterization by protein and gene expression markers at 24 h and 72 h indicated overall stronger macrophage activation and subtle phenotypic skewing towards the M2 phenotype on BCP<μm vs TCP. Moreover, macrophages exhibited an elongated morphology on BCP<μm, which is associated with the M2 phenotype, while macrophages on TCP primarily exhibited a spherical morphology. Conditioned medium of macrophages cultured on BCP<μm resulted in enhanced in vitro angiogenic tube formation and osteogenic differentiation of mesenchymal stromal cells, compared to conditioned medium from macrophages on TCP. Altogether, these findings suggest a potential role of M2 macrophage upregulation in the bone-induction mechanism of calcium phosphates with submicron surface topography.

Calcium Phosphate Delivery Systems for Regeneration and Biomineralization of Mineralized Tissues of the Craniofacial Complex.

Calcium phosphate (CaP)-based materials have been extensively used for mineralized tissues in the craniofacial complex. Owing to their excellent biocompatibility, biodegradability, and inherent osteoconductive nature, their use as delivery systems for drugs and bioactive factors has several advantages. Of the three mineralized tissues in the craniofacial complex (bone, dentin, and enamel), only bone and dentin have some regenerative properties that can diminish due to disease and severe injuries. Therefore, targeting these regenerative tissues with CaP delivery systems carrying relevant drugs, morphogenic factors, and ions is imperative to improve tissue health in the mineralized tissue engineering field. In this review, the use of CaP-based microparticles, nanoparticles, and polymer-induced liquid precursor (PILPs) amorphous CaP nanodroplets for delivery to craniofacial bone and dentin are discussed. The use of these various form factors to obtain either a high local concentration of cargo at the macroscale and/or to deliver cargos precisely to nanoscale structures is also described. Finally, perspectives on the field using these CaP materials and next steps for the future delivery to the craniofacial complex are presented.

Periodontal ligament stem cell-based bioactive constructs for bone tissue engineering.

Objectives: Stem cell-based tissue engineering approaches are promising for bone repair and regeneration. Periodontal ligament stem cells (PDLSCs) are a promising cell source for tissue engineering, especially for maxillofacial bone and periodontal regeneration. Many studies have shown potent results via PDLSCs in bone regeneration. In this review, we describe recent cutting-edge researches on PDLSC-based bone regeneration and periodontal tissue regeneration. Data and sources: An extensive search of the literature for papers related to PDLSCs-based bioactive constructs for bone tissue engineering was made on the databases of PubMed, Medline and Google Scholar. The papers were selected by three independent calibrated reviewers. Results: Multiple types of materials and scaffolds have been combined with PDLSCs, involving xeno genic bone graft, calcium phosphate materials and polymers. These PDLSC-based constructs exhibit the potential for bone and periodontal tissue regeneration. In addition, various osteo inductive agents and strategies have been applied with PDLSCs, including drugs, biologics, gene therapy, physical stimulation, scaffold modification, cell sheets and co-culture. Conclusoin: This review article demonstrates the great potential of PDLSCs-based bioactive constructs as a promising approach for bone and periodontal tissue regeneration.

Application of SC-CO2 in the Technology of the Preparation of Calcium Phosphate Matrices for the Treatment of Septic Purulent Inflammations of Bone Tissues

Application of SC-CO2 in the Technology of the Preparation of Calcium Phosphate Matrices for the Treatment of Septic Purulent Inflammations of Bone Tissues

Synthesis, photothermal effects, and antibacterial properties of lanthanum-doped hydroxyapatite

Hydroxyapatite (HA) is a weakly alkaline, bioactive calcium phosphate material with a composition similar to that of human bones and teeth. However, the high crystallinity of HA materials slows their degradation and new bone formation in a physiological environment, and their poor antibacterial properties make them susceptible to bacterial infections. Human bones contain trace amounts of rare earth elements (e.g. La, Yb, and Ce), with accumulation varying with age. La3+ in the proper concentration range promotes stem cell proliferation and differentiation. Polydopamine (PDA) has a maximum absorption wavelength up to the near-infrared region and can be used as a photothermal reagent. In this study, LaHA (La-doped HA) was prepared using a hydrothermal method with different doping amounts and pH values, and then surface-coated with PDA. This final product, LaHA@PDA, exhibited bone induction properties and photothermal stability, achieving a synergistic antibacterial effect. The results showed that the solution pH and La3+ concentration affected the La3+ doping content and surface morphology. The nanoparticles synthesised at pH = 13 were pure HA in the form of short rods, while the doping amount substantially increased by decreasing the solution pH. The pH and doping amount also influenced the photothermal effect of LaHA@PDA, with 1LaHA13@PDA (pH = 13, doping amount of 1) exhibiting the best photothermal performance. The antibacterial ability of the nanomaterial was further demonstrated through bacterial and in vitro immersion experiments, thereby demonstrating its promising applications in the biomedical field.

Calcium Phosphate Functionalization and Applications in Dentistry

The oral and maxillofacial hard tissues support the maxillofacial shape and serve as the foundation for functional activities. Defects in these tissues not only impair patients’ ability to perform their normal physiological functions but also have a significant negative impact on their psychological well-being. Moreover, these tissues have a limited capacity for self-healing, necessitating the use of artificial materials to repair defects. Calcium phosphate is a fine-grained inorganic biomineral found in vertebrate teeth and bones that has a comparable composition to human hard tissues. Calcium phosphate materials are biocompatible, bioactive, and osteogenic for hard tissue repair, despite drawbacks such as poor mechanical qualities, limiting their clinical efficacy and application. With the advancement of materials science and technology, numerous techniques have been developed to enhance the characteristics of calcium phosphate, and one of them is functionalization. Calcium phosphate can be functionally modified by changing its size, morphology, or composition through various preparation processes to achieve multifunctionality and improve physical and chemical properties, biocompatibility, and osteogenic potential. The purpose of this review is to provide new ideas for the treatment of oralmaxillofacial hard tissue defects and deficiencies by summarizing the functionalization strategies of calcium phosphate materials and their applications in dentistry.

UROLITHIASIS IN FOXES: ASSESSMENT OF 65 UROLITH SUBMISSIONS TO THE MINNESOTA UROLITH CENTER FROM 1981 TO 2021.

This article summarizes urinary stone submissions from foxes in human care to the Minnesota Urolith Center over 40 years. A previous report documented the analysis of uroliths from foxes that were submitted between 1981 and 2007.13 New data compiled from 2008 to 2021 included an additional 38 stones submitted from foxes, totaling 65 fox urolith submissions from 1981 to 2021. Struvite and cystine uroliths were most common, with the remainder comprised of calcium phosphate, calcium oxalate, compound, mixed, or miscellaneous material. Most stones were submitted from male foxes. Seventy-two percent of the stones were urocystoliths, and from 2010 to 2021, most stones were diagnosed antemortem and removed surgically. More than half of the stones were submitted from red foxes (Vulpes vulpes) and fennec foxes (Vulpes zerda). Urolithiasis in foxes may be an underrecognized condition, and data from this study suggest that clinicians should consider routine urinalysis and diagnostic imaging as part of the preventive medicine program for fox species, especially red foxes and fennec foxes.

Injectable demineralized bone matrix particles and their hydrogel bone grafts loaded with β-tricalcium phosphate powder and granules: A comparative study.

Demineralized bone matrix (DBM), has been used as a bone-graft material because of its osteoconductivity and osteoinductivity. However, the previous research report that supports the single use of DBM is limited by its rapid resorption caused by the lack of calcium and phosphate. β-Tricalcium phosphate (TCP) is an enriched calcium phosphate material suitable for bone healing with osteoconductive properties. In this study, we have developed injectable bone graft by the loading two kinds of TCP in DBM particles and thermo-sensitive DBM-derived hydrogel (hDBM). TCP powder (pTCP) and TCP granules (gTCP) were loaded into hDBM and DBM, respectively. The bone formation effect was investigated according to the morphological features of TCP. Residual growth factor concentrations were investigated; microstructure and morphology were characterized by SEM. In-vitro studies showed that hDBM/DBM/pTCP and hDBM/DBM/gTCP bone grafts were biocompatible and could promote osteogenesis by up-regulating the expression of Runx2 and OPN, bone-related genes. In-vivo studies using the rabbit-femur defect model revealed that the implanted hDBM/DBM/pTCP bone graft showed similar histology to that of fibrous dysplasia with the expression of CD68, whereas hDBM/DBM/gTCP showed good bone formation. Loading of gTCP in place of pTCP was noticed as an effective way to improve bone regeneration in an injectable hDBM/DBM hydrogel-based bone graft.

Extraction and Characterization of Natural Calcium Phosphate Materials from &lt;i&gt;Lutjanus johnii&lt;/i&gt; and &lt;i&gt;Lutjanus sebae&lt;/i&gt; Fish Bone Bio-Wastes

Fish processing by-products, such as fish bone waste is usually considered as waste and will be disposed without fully utilizing it. Indeed, this by-product can serve as a cheap bio-resource for the production of high-value product, for instance, as an inexpensive source of calcium phosphate material. In this research, Lutjanus johnii and Lutjanus sebae bones were subjected to thermal calcination to yield different calcium phosphate products. XRD, FTIR and HRTEM-SAED results revealed that biphasic HAp/β-TCP mixture was obtained by heat treatment of Lutjanus johnii bone while a single-phase HAp was prepared from Lutjanus sebae bone. In addition, it was shown that both Lutjanus johnii and Lutjanus sebae bones had a merit in producing B-type carbonated composition that is advantageous for biomedical application. EDX result further corroborated the existence of inorganic elements such as Mg, Na and Sr. With their unique composition, the calcined products deriving from Lutjanus johnii and Lutjanus sebae bones can be further employed to form bioceramic scaffolds for bone engineering applications.

Synthesis of Biocompatible Composite Material Based on Cryogels of Polyvinyl Alcohol and Calcium Phosphates.

At the moment, the field of biomedical materials science is actively developing, which aims at creating new functional materials. A developing direction in biomedical materials science is that towards the treatment of diseases associated with bone tissue disorders, using biodegradable composite materials based on polymer and calcium phosphate materials. We developed a material based on polyvinyl alcohol cryogel, mineralized with calcium phosphate. A material based on cryogel of polyvinyl alcohol mineralized with calcium phosphate was developed. The composites were obtained by the method of cyclic freezing–thawing, and the synthesis of calcium phosphates was carried out in situ with heating, stirring, and exposure to microwave radiation. The phase composition, as well as the composition of functional groups, was determined by IR spectroscopy and X-ray phase analysis. Monocytes isolated from human blood showed higher viability compared to the controls.

Powder 3D Printing of Bone Scaffolds with Uniform and Gradient Pore Sizes Using Cuttlebone-Derived Calcium Phosphate and Glass-Ceramic.

The pore geometry of bone scaffolds has a major impact on their cellular response; for this reason, 3D printing is an attractive technology for bone tissue engineering, as it allows for the full control and design of the porosity. Calcium phosphate materials synthesized from natural sources have recently attracted a certain interest because of their similarity to natural bone, and they were found to show better bioactivity than synthetic compounds. Nevertheless, these materials are very challenging to be processed by 3D printing due to technological issues related to their nanometric size. In this work, bone scaffolds with different pore geometries, with a uniform size or with a size gradient, were fabricated by binder jetting 3D printing using a biphasic calcium phosphate (BCP) nanopowder derived from cuttlebones. To do so, the nanopowder was mixed with a glass-ceramic powder with a larger particle size (45–100 µm) in 1:10 weight proportions. Pure AP40mod scaffolds were also printed. The sintered scaffolds were shown to be composed mainly by hydroxyapatite (HA) and wollastonite, with the amount of HA being larger when the nanopowder was added because BCP transforms into HA during sintering at 1150 °C. The addition of bio-derived powder increases the porosity from 60% to 70%, with this indicating that the nanoparticles slow down the glass-ceramic densification. Human mesenchymal stem cells were seeded on the scaffolds to test the bioactivity in vitro. The cells’ number and metabolic activity were analyzed after 3, 5 and 10 days of culturing. The cellular behavior was found to be very similar for samples with different pore geometries and compositions. However, while the cell number was constantly increasing, the metabolic activity on the scaffolds with gradient pores and cuttlebone-derived powder decreased over time, which might be a sign of cell differentiation. Generally, all scaffolds promoted fast cell adhesion and proliferation, which were found to penetrate and colonize the 3D porous structure.

A novel method for coating calcium phosphate with trace elements extracted from bone using electrical stimulation

Hydroxyapatite (HAp) is a biomaterial used because of its high potential for improving the healing of bone fractures. HAp is typically prepared using synthetic methods. However, synthetic HAp generally does not contain trace elements, which are considered to be important factors in the healing process. Therefore, researchers have focused on developing methods for preparing biomaterials containing trace elements. A novel method for coating calcium phosphate materials with trace elements is proposed in this study. In this method, mineral components with trace elements were obtained from bone samples and coated onto the titanium surface using only electrical stimulation under constant voltage application in phosphate-buffered saline. The resulting material had poor crystallinity, which was similar to apatite structure present in bone tissue, and it contained trace elements. Calcium phosphate depositions were also constructed on the surfaces of bone and vascular specimens under the same conditions. Consequently, this method can potentially be applied as an innovative treatment for implant surfaces and in the preparation of scaffolds for bone tissue engineering.

Tunable Behavior in Solution of Amorphous Calcium Ortho/Pyrophosphate Materials: An Acellular In Vitro Study.

Amorphous calcium phosphate-based materials are of major interest in the field of bone substitution. Very recently, the low-temperature synthesis of a new family of amorphous calcium phosphate containing both orthophosphate and pyrophosphate ions in controlled proportions has been reported. Despite their interest, especially due to the biochemical role and the hydrolysis of pyrophosphate occurring in vivo, the behavior of such materials when interacting with aqueous media has never been described. Consequently, we herein report the in vitro acellular evolution of three compositions of mixed calcium ortho- and pyrophosphate amorphous materials including a different orthophosphate proportion. As a first step to assess the physicochemical reactivity of these amorphous materials, they were tested in two different media at 37 °C, acidified water and simulated body fluid solution, from 1 h up to 15 days. The results demonstrated that they were quite stable and that they progressively released part of their constitutive ions, highlighting their potential for controlled delivery of bioactive ions (calcium, orthophosphate, and pyrophosphate ions). In addition to these properties, we showed that the material with the highest ortho/(ortho + pyro) phosphate ratio started to crystallize into nanocrystalline apatite analogous to bone mineral within 2 days or 2 weeks depending on the medium. For the other material compositions, no layer of apatite was detected at their surface with SBF testing despite the favorable supersaturation indexes, crystallization being probably inhibited by pyrophosphate ions released in the medium. This varying apatite-forming ability emphasizes the key role of the ortho/(ortho + pyro) phosphate ratio of these materials in their in vitro reactivity and bioactivity, which paves the way for the development of this promising family of amorphous calcium phosphate materials with tunable physicochemical and biological properties.

Composition and structure of calcium-phosphate coatings on Ti3AlC2 produced by sol-gel synthesis

Calcium phosphate materials have been widely used in medical practice for decades. Due to their bioactivity and integration with human hard tissues. They have been produced in the form of dense and porous ceramics, powders and needle-like crystals (whiskers). Despite the high mechanical properties (hardness, compressive strength), calcium phosphate ceramics are mainly used in medicine mainly as the fillers for bone defects formed due to injuries or diseases because they have high fragility and low crack resistance. These circumstances do not allow using them in the sites that have high mechanical loads (e.g. hip surgery). To solve these problems metal implants are used. Among them, Ti-based alloys are the most widely used due to its high mechanical properties, biocompatibility and high corrosion resistance. Recently, the data on the use of MAX phases as medical materials to create the composites based on Ti3SiC2 have appeared in the literature. Calcium phosphate coatings were obtained on Ti3AlC2 substrate by the sol-gel method. The effect of temperature, holding time, chemical compositions of reactants on the phase composition and structure of the samples are discussed. XRD measurements have revealed that the initial coatings consists of nanoparticles sized 10-50 nm. Light and scanning electron microscopy (SEM) were applied to study the morphology of the coatings. It have been shown that the coatings had thickness in an interval 40-100 mm and had the homogenous structure. It has been established by X-ray phase identification that the coating after heating at 1000oC during 1 hour contained b-tricalcium phosphate (b-TCP). It was found, that the thickness and phase composition of coatings depend on the time of coating in calcium phosphate solution. The optimal conditions for the formation of coatings are established.