Electron Paramagnetic Resonance Characterization of Sodium- and Carbonate-Containing Hydroxyapatite Cement.

Ionizing radiation-induced paramagnetic defects in calcified tissues like tooth enamel are indicators of irradiation dose. Hydroxyapatite (HA), the principal constituent in these materials, incorporates a variety of anions (CO, F, Cl, and SiO) and cations (Mn, Li, Cu, Fe, Mg, and Na) that directly or indirectly contribute to the formation of stable paramagnetic centers upon irradiation. Here, we used an underexploited synthesis method based on the ambient temperature setting reaction of a self-hardening calcium phosphate cement (CPC) to create carbonate-containing hydroxyapatite (CHA) and investigate its paramagnetic properties following γ-irradiation.

Engineering 3D Printed Scaffolds with Tunable Hydroxyapatite.

Orthopedic and craniofacial surgical procedures require the reconstruction of bone defects caused by trauma, diseases, and tumor resection. Successful bone restoration entails the development and use of bone grafts with structural, functional, and biological features similar to native tissues. Herein, we developed three-dimensional (3D) printed fine-tuned hydroxyapatite (HA) biomimetic bone structures, which can be applied as grafts, by using calcium phosphate cement (CPC) bioink, which is composed of tetracalcium phosphate (TTCP), dicalcium phosphate anhydrous (DCPA), and a liquid [Polyvinyl butyral (PVB) dissolved in ethanol (EtOH)].

Biofabrication of 3D printed hydroxyapatite composite scaffolds for bone regeneration.

Biofabrication has been adapted in engineering patient-specific biosynthetic grafts for bone regeneration. Herein, we developed a three-dimensional (3D) high-resolution, room-temperature printing approach to fabricate osteoconductive scaffolds using calcium phosphate cement (CPC). The non-aqueous CPC bioinks were composed of tetracalcium phosphate, dicalcium phosphate anhydrous, and Polyvinyl butyral (PVB) dissolved in either ethanol (EtOH) or tetrahydrofuran (THF).

Iron oxide nanoparticle-calcium phosphate cement enhanced the osteogenic activities of stem cells through WNT/β-catenin signaling.

Calcium phosphate cement (CPC), functionalized with iron oxide nanoparticles (IONP), is of great promise to promote osteoinduction and new bone formation. In this work, the IONP powder was added into the CPC powder to fabricate CPC + IONP scaffolds and the effects of the novel composite on bone matrix formation and osteogenesis of human dental pulp stem cells (hDPSCs) were explored. A series of CPC + IONP magnetic scaffolds with different IONP contents (1%, 3% and 6%) were fabricated using 5% chitosan solution as the cement liquid.

Calcium phosphate cements for bone engineering and their biological properties.

Calcium phosphate cements (CPCs) are frequently used to repair bone defects. Since their discovery in the 1980s, extensive research has been conducted to improve their properties, and emerging evidence supports their increased application in bone tissue engineering. Much effort has been made to enhance the biological performance of CPCs, including their biocompatibility, osteoconductivity, osteoinductivity, biodegradability, bioactivity, and interactions with cells.

Effect of calcium phosphate nanocomposite on in vitro remineralization of human dentin lesions.

Objective: Secondary caries is a primary reason for dental restoration failures. The objective of this study was to investigate the remineralization of human dentin lesions in vitro via restorations using nanocomposites containing nanoparticles of amorphous calcium phosphate (NACP) or NACP and tetracalcium phosphate (TTCP) for the first time.

Methods: NACP was synthesized by a spray-drying technique and incorporated into a resin consisting of ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM).

Rechargeable calcium phosphate orthodontic cement with sustained ion release and re-release.

White spot lesions (WSL) due to enamel demineralization are major complications for orthodontic treatments. Calcium phosphate (CaP) dental resins with Ca and P ion releases are promising for remineralization. However, previous Ca and P releases lasted for only weeks.

Novel rechargeable calcium phosphate dental nanocomposite.

Objectives: Calcium phosphate (CaP) composites with Ca and P ion release can remineralize tooth lesions and inhibit caries. But the ion release lasts only a few months. The objectives of this study were to develop rechargeable CaP dental composite for the first time, and investigate the Ca and P recharge and re-release of composites with nanoparticles of amorphous calcium phosphate (NACP) to achieve long-term inhibition of caries.

Injectable nanoamorphous calcium phosphate based in situ gel systems for the treatment of periapical lesions.

Nonsurgical local treatment of a periapical lesion arising from trauma or bacterial infection is a promising innovative approach. The present study investigated the feasibility of developing injectable amorphous calcium phosphate nanoparticles (ACP NPs) and ACP NPs loaded with an anti-inflammatory drug; ibuprofen (IBU-ACP NPs) in the form of thermoreversible in situ gels to treat periapical lesions with the stimulation of bone formation. NPs were produced by a spray-drying technique.

Oral fluoride levels 1 h after use of a sodium fluoride rinse: effect of sodium lauryl sulfate.

Increasing the concentration of free fluoride in oral fluids is an important goal in the use of topical fluoride agents. Although sodium lauryl sulfate (SLS) is a common dentifrice ingredient, the influence of this ion on plaque fluid and salivary fluid fluoride has not been examined. The purpose of this study was to investigate the effect of SLS on these parameters and to examine the effect of this ion on total (or whole) plaque fluoride, an important source of plaque fluid fluoride after a sufficient interval following fluoride administration, and on total salivary fluoride, a parameter often used as a surrogate measure of salivary fluid fluoride.

Development of a novel fluorapatite-forming calcium phosphate cement with calcium silicate: in vitro and in vivo characteristics.

Aim of this study was to develop a novel fluorapatite-forming calcium phosphate cement (FA-CPC) with tricalcium silicate (TCS) for endodontic applications and to examine its in vitro and in vivo characteristics. The FA-CPC powder consisted of 62.8% CaHPO4, 30.

Immobilization of Xanthate Agent on Titanium Dioxide and Surface Initiated RAFT Polymerization.

Surface modification of titanium dioxide (TiO) nanoparticle is essential to control its surface properties, thereby to enhance its cell penetration capability, reduce its cytotoxicity, or improve its biocompatibility. In order to graft polyvinyl acetate onto TiO nanoparticles, xanthate was chemically immobilized on the surface of TiO by acylation followed by nucleophilic substitution with a carbodithioate salt. Reversible addition fragmentation chain transfer polymerization was conducted to graft vinyl acetate onto the surface of TiO.

Effects of Inorganic Fillers on the Thermal and Mechanical Properties of Poly(lactic acid).

Addition of filler to polylactic acid (PLA) may affect its crystallization behavior and mechanical properties. The effects of talc and hydroxyapatite (HA) on the thermal and mechanical properties of two types of PLA (one amorphous and one semicrystalline) have been investigated. The composites were prepared by melt blending followed by injection molding.

In-situ hybridization of calcium silicate and hydroxyapatite-gelatin nanocomposites enhances physical property and in vitro osteogenesis.

Low mechanical strengths and inadequate bioactive material-tissue interactions of current synthetic materials limit their clinical applications in bone regeneration. Here, we demonstrate gelatin modified siloxane-calcium silicate (GEMOSIL-CS), a nanocomposite made of gelatinous hydroxyapatite with in situ pozzolanic formation of calcium silicate (CS) interacting among gelatin, silica and Calcium Hydroxide (Ca(OH)2). It is shown the formation of CS matrices, which chemically bonds to the gelatinous hydroxyapatite, provided hygroscopic reinforcement mechanism and promoted both in vitro and in vivo osteogenic properties of GEMOSIL-CS.

A New Bioactive Polylactide-based Composite with High Mechanical Strength.

A new bioresorbable polylactide/calcium phosphate composite with improved mechanical strengths and a more basic filler, tetracalcium phosphate (TTCP), was prepared by melt compounding. N-(2-aminoethyl)-3-aminoproplytrimethoxysilane (AEAPS) and pyromellitic dianhydride (PMDA) were used to improve the interfacial adhesion between TTCP and polylactide (PLA). While AEAPS improved the dispersion of TTCP in the matrix, PMDA might react with the terminal hydroxyl group of PLA and the amino group on the surface of AEAPS modified TTCP, which could further enhance the interfacial strength.

Antibacterial activity and ion release of bonding agent containing amorphous calcium phosphate nanoparticles.

Objective: Recurrent caries at the margins is a primary reason for restoration failure. The objectives of this study were to develop bonding agent with the double benefits of antibacterial and remineralizing capabilities, to investigate the effects of NACP filler level and solution pH on Ca and P ion release from adhesive, and to examine the antibacterial and dentin bond properties.

Methods: Nanoparticles of amorphous calcium phosphate (NACP) and a quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM) were synthesized.

Long-term mechanical durability of dental nanocomposites containing amorphous calcium phosphate nanoparticles.

Half of all dental restorations fail within 10 years, with secondary caries and restoration fracture being the main reasons. Calcium phosphate (CaP) composites can release Ca and PO(4) ions and remineralize tooth lesions. However, there has been no report on their long-term mechanical durability.

Improve the Strength of PLA/HA Composite Through the Use of Surface Initiated Polymerization and Phosphonic Acid Coupling Agent.

Bioresorbable composite made from degradable polymers, e.g., polylactide (PLA), and bioactive calcium phosphates, e.

Nanofiber scaffold gradients for interfacial tissue engineering.

We have designed a 2-spinnerette device that can directly electrospin nanofiber scaffolds containing a gradient in composition that can be used to engineer interfacial tissues such as ligament and tendon. Two types of nanofibers are simultaneously electrospun in an overlapping pattern to create a nonwoven mat of nanofibers containing a composition gradient. The approach is an advance over previous methods due to its versatility - gradients can be formed from any materials that can be electrospun.

A new approach to prepare well-dispersed CaF(2) nanoparticles by spray drying technique.

Previously, nano-sized calcium fluoride (CaF₂) particles were prepared using a spray drying method by simultaneously feeding Ca(OH)₂ and NH₄F solutions to a two-liquid nozzle. The aim of the present study was to prepare better-dispersed nano-CaF₂ particles by co-forming a soluble salt, sodium chloride (NaCl). NaCl of various concentrations were added to the NH(4) F solution, leading to formation of (CaF₂ +NaCl) composites with CaF₂ /NaCl molar ratios of 4/1, 4/4, and 4/16.

Nanocomposite containing amorphous calcium phosphate nanoparticles for caries inhibition.

Objectives: The main challenges facing composite restorations are secondary caries and bulk fracture. The objectives of this study were to synthesize novel nanoparticles of amorphous calcium phosphate (NACP), develop NACP nanocomposite with calcium (Ca) and phosphate (PO(4)) ion release to combat caries, and investigate the effects of NACP filler level and glass co-filler reinforcement on composite properties.

Methods: NACP (diameter=116 nm) were synthesized via a spray-drying technique for the first time.

Mechanical and acid neutralizing properties and bacteria inhibition of amorphous calcium phosphate dental nanocomposite.

Dental composites do not hinder bacteria colonization and plaque formation. Caries at the restoration margins is a frequent reason for replacement of existing restorations, which accounts for 50 to 70% of all restorations. The objectives of this study were to examine the filler level effect on nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) and investigate the load-bearing and acid-neutralizing properties and bacteria inhibition.

Properties of Injectable Apatite-Forming Premixed Cements.

Previous studies reported premixed calcium phosphate cements (CPCs) that were stable in the package and form hydroxyapatite (HA) as the product after exposure to an aqueous environment. These cements had setting times of greater than 60 min, which are too long to be useful for some clinical applications. The present study investigated properties of fast-setting HA-forming premixed CPCs that initially consisted of two separate premixed pastes: (1) finely ground (1.

In Vitro and in Vivo Characteristics of Fluorapatite-Forming Calcium Phosphate Cements.

This study reports for the first time in vitro and in vivo properties of fluorapatite (FA)-forming calcium phosphate cements (CPCs). The experimental cements contained from (0 to 3.1) mass % of F, corresponding to presence of FA at levels of approximately (0 to 87) mass %.