Calcium Phosphate Gel Research Articles

Topical fluoride treatment effectiveness: a systematic review

Relevance. The systematic review aimed to evaluate the effectiveness of topical fluoride in children based on the analysis of modern randomized clinical trial (RCT) data.Materials and methods. This review was carried out using the PRISMA checklist (the Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The proposed criteria determined the quality of the studies for inclusion in the review and then during the result summary. A preliminary search was conducted among articles published between 2013 and 2023 where fluoride varnishes were one of the preventive products. The search included MeSH terms, the keywords "fluorides", "fluorine varnish", "caries prevention", "remineralisation", and "children". A preliminary search found 346 studies. After excluding duplicates and irrelevant studies, two independent reviewers analysed nine RCTs based on the PRISMA criteria.Results. Children aged eight months to five years old participated in five out of nine RCTs on the fluoride varnish application included in the review, and four studies included adolescents aged 14–20 y.o. The duration of the studies ranged from 2 months to 3.5 years. Six studies described the use of fluoride varnish in children, and three studies reported on the application of calcium phosphate gels with fluoride versus fluoride varnish. Various ways determined enamel condition, namely, visual method, digitally processed photography, analysis of radiographs, QLF (quantitative light fluorescence method), and laser fluorescence analysis method (Diagnodent). The dmft, ICDAS indices, caries increment, the WSL (white spot lesion) index, and the assessment of changes in the tooth damage area evaluated the prevalence and intensity of caries. In the control groups, most studies used 1000 to 1500 ppm fluoride toothpastes according to the usual scheme. None of the studies statistically proved the additional preventive effectiveness of the fluoride varnishes.Conclusions. The analysis of RCTs did not reveal the advantages of fluoride varnishes for caries prevention in children and adolescents compared to standard oral hygiene procedures using fluoride toothpastes.

Enhancing of teeth remineralization by electric field aid (in vitro study)

One of the major challenges in teeth remineralization is the slow rate of mineralization. In this study, an electric-field-aided mineralization system was developed for rapidly regenerating teeth-like structures rapidly. The efficacy of application of an electric field combined with nano-chitosan gel, casein phosphopeptide–amorphous calcium phosphate gel and their mixture was investigated as a remineralizing accelerator for artificially demineralized teeth. Teeth samples were demineralized by using ethylenediaminetetraacetic acid and subsequently subjected to treatment with each gel alone and in combination with an electric field (20 mA, 5 min). The structural analyses of the teeth samples were performed by using a scanning electron microscope and X-ray diffraction patterns, and their hardness was obtained through Vickers microhardness tests. The results revealed that the addition of chitosan to casein phosphopeptide–amorphous calcium phosphate enhanced the remineralization of the tooth structure compared with using each one individually. Furthermore, the application of an electric field enhanced teeth hardness and showed the highest rate of remineralization. In conclusion, the proposed technique could be safely used to reduce the time consumed in remineralization and it may be used efficiently to increase tooth quality. It is suggested to study other biophysical parameters of using electric fields for in vivo applications.

Evaluation of Enamel Acid Resistance and Whitening Effect of the CAP System.

This study aimed to compare the effectiveness of a novel professional tooth-strengthening system and a conventional caries-prevention method that involved the use of high fluoride concentrations, to determine whether the system has a whitening effect. Bovine tooth-enamel samples were treated with fluoride gel (conventional APF method) or a mixture of citric acid gel, calcium phosphate (α-TCP), and fluoride gel, referred to as the CAP system; these treatments were performed to generate an acid-resistant layer on the enamel surface. For the evaluation of the acid resistance, a cyclic experiment, involving a 1-h remineralization and a 24-h acid treatment, was conducted thrice after the treatments. The height profiles were observed using a 3D-measuring laser microscope and the hardness was evaluated by Vickers hardness test. The morphological changes in the surface and cross-section of the enamel were observed by scanning electron microscopy. To evaluate the whitening effect, the enamel was ground until the color of the underlying dentin was recognizable; the CAP system was applied once, and the color change was measured using a color difference meter. As a result, it was confirmed that an acid-resistant layer was formed on the tooth surfaces treated with the CAP system, and a whitening effect was obtained.

Efficacy of fluoride varnish containing xylitol coated calcium phosphate or potassium nitrate gel versus conventional fluoride varnish in management of hypersensitivity of exposed root surfaces in adult patients: A randomized clinical trial

Objective: This clinical trial was conducted to compare the efficacy of fluoride varnish containing xylitol coated calcium and phosphate or potassium nitrate gel versus conventional fluoride varnish in the management of hypersensitivity of non-carious exposed root surfaces in adult patients. Material and Methods: 35 patients having 105 hypersensitive teeth were randomly allocated to be treated either using Embrace varnish (PULPDENT Corporation, Watertown, MA, USA) or UltraEz gel (Ultradent Products Inc. South Jordan, UT, USA) or Fluoride varnish FluoroDose (Centrix Inc., Milford, Connecticut, USA), all agents were used according to the manufacturers’ instructions. Hypersensitivity scores were assessed using the visual analogue scale (VAS), after applying different stimuli. The assessment was done at baseline, after 4 hours of application, after two days, then after 4, 8 and 12 months. Results: UltraEZ gel showed the best immediate relief with a significant difference from other treatment methods, fluoride varnish showed the best relief at both short and long term follow up periods. Embrace varnish showed the least success in reducing hypersensitivity. Conclusions: Fluoride varnish showed the best reduction in hypersensitivity values while UltraEZ showed the best immediate relief and Embrace varnish showed the least efficacy

Nanostructured Zn-Substituted Monetite Based Material Induces Higher Bone Regeneration Than Anorganic Bovine Bone and β-Tricalcium Phosphate in Vertical Augmentation Model in Rabbit Calvaria.

The capacity of a nanostructured multicomponent material composed of Zn-substituted monetite, amorphous calcium phosphate, hydroxyapatite and silica gel (MSi) to promote vertical bone augmentation was compared with anorganic bovine bone (ABB) and synthetic β-tricalcium phosphate (β-TCP). The relation between biological behavior and physicochemical properties of the materials was also studied. The in vivo study was conducted in a vertical bone augmentation model in rabbit calvaria for 10 weeks. Significant differences in the biological behavior of the materials were observed. MSi showed significantly higher bone regeneration (39%) than ABB and β-TCP (24%). The filled cylinder volume was similar in MSi (92%) and ABB (91%) and significantly lower in β-TCP (81%) implants. In addition, β-TCP showed the highest amount of non-osteointegrated particles (17%). MSi was superior to the control materials because it maintains the volume of the defect almost full, with the highest bone formation, the lowest number of remaining particles, which are almost fully osteointegrated and having the lowest amount of connective tissue. Besides, the bone formed was mature, with broad trabeculae, high vascularization and osteogenic activity. MSi resorbs gradually over time with an evident increment of the porosity and simultaneous colonization for vascularized new bone. In addition, the osteoinductive behavior of MSi material was evidenced.

Comparison of CPP-ACP, Fluoride Varnish and Gel effects on enamel microhardness of permanent teeth: In-Vitro

Background Dental caries occurs due to the imbalance in the course of demineralization-remineralization in favor of demineralization. With remineralization, some signs of halted progression could be observed in the primary stages. The aim of this study is to in-vitro investigation of the effect of Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP), fluoride varnish, and fluoride gel on the microhardness of the enamel of permanent teeth. Materials and Methods: In this in vitro study, 344 specimens prepared from human premolars were randomly divided into four groups (n=86 specimens in each group). After preparing the specimens, the initial enamel value was first evaluated by Vickers microhardness technique. The specimens were immersed in a demineralizing solution and then treated with remineralizing compounds (I. Control, II. Fluoride varnish, III. Fluoride gel and IV. CPP-ACP). Microhardness values were re-measured at the end of demineralization and remineralization stages. The data were analyzed using SPSS software (version 16.0). Results: The results of the present study indicated a statistically significant difference in all groups in terms of initial enamel microhardness (0.288 ± 42.77), remineralization (0.213 ± 26.89), and demineralization values (0.167 ± 63.87) (p <0.001). Besides, there was a statistically significant difference in different groups in terms of remineralization values (p <0.001). In other words, the mean microhardness was 241.21 ±15.60 in Group III, 221.12 ± 75.69 in Group II, 211.16 ± 43.04 in Group IV, and 178.21 ± 63.9 in group- I. Conclusion All remineralizing compounds resulted in enhanced microhardness of the enamel. Nevertheless, the fluoride-containing products showed greater potential in improving the level of microhardness and strength of the teeth compared to the compounds containing CPP-ACP.

Novel approach to enhancing remineralization of tooth surface by magnetic field exposure

Modern dentistry is directed toward overcoming dental caries progression in the early stages with the aid of remineralizing agents. Long-established remineralizing agents have very slow kinetics to be applicable, and the need for an external cofactor is a must. In the present work, the authors improved the kinetics of dentin/enamel remineralization by magnetic field exposure whereby calcium (Ca2+) and phosphate (PO4 3−) elements are supplied from an external source. Gels made of casein phosphopeptide–amorphous calcium phosphate mixed with nanochitosan were used as an external source and combined with exposure of the tooth surface to a magnetic field of 1.8 mT for 20 min. The treated tooth samples were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Vickers microhardness test and X-ray diffraction. The obtained tooth characteristics confirmed the improvement of tooth surface integrity, mineralization, hardness and crystallinity under the application of the magnetic field. Unexpectedly, the results indicated the highest tooth surface remineralization for samples exposed to magnetic fields and treated with casein phosphopeptide–amorphous calcium phosphate gel only without nanochitosan. In conclusion, the resulting advantages here are the ease of use, safety and applicability of this novel combination of casein phosphopeptide–amorphous calcium phosphate gel with magnetic field exposure.

Novel Osteoinductive and Osteogenic Scaffolds of Monetite, Amorphous Calcium Phosphate, Hydroxyapatite, and Silica Gel: Influence of the Hydroxyapatite/Monetite Ratio on Their In Vivo Behavior and on Their Physical and Chemical Properties.

In this work, a new family of multiphasic materials composed of the same amount of silica gel and variable amount of three calcium phosphates with very different solubilities, monetite > amorphous calcium phosphate > hydroxyapatite (HAp), was studied. Silicon was added to calcium phosphate to increase bioactivity and osteinductivity. The influence of the HAp/monetite ratio on the material resorption and bone regeneration was investigated in critical bone defects in sheep and was related to their chemical and physical properties. It was concluded that a minimum rate of HAp/monetite is necessary to achieve an appropriate compromise between material resorption and bone regeneration. Above this minimum rate, bone regeneration and material resorbtion did not change significantly. Physical properties such as particle size, specific surface area, porosity, and granulate cohesion played a more critical role on material resorption than the solubility of their components. A huge difference between in vitro solubility and in vivo resorption was observed. It was related to the fastest cellular-mediated resorption of monetite compared to the other components. Computerized axial tomography, histology, histomorphometric, and multiple fluorochrome labeling studies showed a very advanced bone regeneration of the defects when materials with the highest HAp/monetite rate were implanted. It was also demonstrated that all materials induce bone formation and vascularization.

A Combination of Biphasic Calcium Phosphate (Maxresorb®) and Hyaluronic Acid Gel (Hyadent®) for Repairing Osseous Defects in a Rat Model

The aim of this in vivo study was to evaluate the efficacy of biphasic calcium phosphate (Maxresorb®, BCP) used in combination with hyaluronic acid (Hyadent®, HyA) gel for regeneration of osseous defects in a rat model. Bilateral femoral condylar bone defects (3 mm diameter and 3 mm depth) were created in 40 male Wistar rats. The defects were grafted as group I (BCP only), group II (BCP + HyA), group III (HyA only), and group IV (empty control). At four weeks and 10 weeks, the bone specimens were evaluated using histological and histomorphometrical analyses to identify the newly formed bone area (NF-BA (%)), as well as the remaining BCP particles (R-BCP (%)). Light microscopic examination indicated the absence of an inflammatory reaction within the bone defects after four weeks or 10 weeks of implantation. Significant new bone regeneration was present in the bone defects grafted with BCP or BCP + HyA biomaterials, as early as four weeks, compared to control groups. The addition of HyA to BCP did not significantly improve bone regeneration at four weeks or 10 weeks. Nevertheless, its role in bone healing and regeneration warrants further investigation.

Evaluation Of Anti-Rabies Hyperimmune Serum Prepared Using Different Adjuvants

ABSTRACT Hyper immune antirabies serum have been prepared in horses using inactivated and live attenuated rabies ERA vaccines with three different adjuvants including 20% Rehydra gel ; 5% Pet gel-A and 20% calcium phosphate gel. Such preparation was conducted through inoculation of each of three horse groups with 8 increased doses (one dose twice weekly) of an inactivated vaccine followed by 4 doses of a live attenuated vaccine (one dose twice weekly) with the same adjuvant. All prepared vaccine formulae were found to be free from foreign contaminants and safe with no post inoculation abnormal signs in inoculated mice. Monitoring of the levels of exhibited rabies antibodies in the sera of immunized horses using serum neutralization test (SNT) and Rabies virus antibody quantitative ELISA kit revealed that the prepared rabies vaccines with 5% Pet gel A adjuvant induced the highest antibody titers (2048 by SNT and 2.20 by ELISA kit) with expected protection percentage 96.14% followed by those induced by 20% Calcium phosphate gel recording the values of 2048 by SNT and 2.11 by ELISA kit with expected protection percentage 92.2%. Lower values (1024 by SNT; 2.05 by ELISA kit and 89.59% protection percentage) were recorded for the Rehydra gel adjuvanted vaccine. These obtained data reflect the safety and potency of the prepared horse anti-rabies hyper immune serum (HARHIS) to be used for post exposure treatment in emergency cases and that is the Pet gel A was the best adjuvant to be used.

Sialic acid-modified dexamethasone lipid calcium phosphate gel core nanoparticles for target treatment of kidney injury.

Acute kidney injury (AKI) is a common clinical disease with high morbidity and mortality. Glucocorticoids are drugs that effectively relieve AKI, but the systemic side effects of long-term use limit their use. Herein, we constructed sialic acid-modified dexamethasone sodium phosphate (Dsp)-loaded lipid calcium phosphate gel core nanoparticles (SA-NPs) for the targeted treatment of ischemia-reperfusion (I/R)-induced AKI to improve efficacy and reduce side effects. The obtained nanoparticles could effectively encapsulate Dsp with 66.8% encapsulation efficiency and 4.56% (w/w) drug content. In vitro release indicates that the nanoparticles have a certain sustained release effect and have the characteristics of acid-sensitive release. And SA-NPs significantly increased the cellular uptake and kidney accumulation respectively through the combination of SA and E-selectin receptors overexpressed in inflamed vascular endothelial cells. Besides, the in vivo pharmacokinetic studies showed that Dsp-loaded SA-NPs significantly increased the residence time in the body and their plasma half-life was 1.7 times that of free Dsp. SA-NPs significantly improved the renal function, decreased the level of pro-inflammatory factors, and adjusted the oxidative stress factors and apoptotic proteins compared to free Dsp solution in pharmacodynamic studies. Moreover, little negative effects on blood glucose and bone mineral density were observed. Our study might provide a new strategy for the safe and effective targeting treatment of AKI or other related inflammatory diseases.

Assessment of the resin infiltration and CPP-ACP applications before orthodontic brackets bonding.

The aim of this study is to investigate the efficiency of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) gel and resin infiltrant on decalcified enamel, and to explain the correlation, if any, between ion release capacities and shear bond strength (SBS). A total of 80 premolar teeth were used (n=20). Group I was the control, while a demineralization protocol was performed for other groups. CPP-ACP gel and resin infiltrant, respectively, was applied to Groups III and IV. Pre and post-demineralization energy dispersive X-Ray analysis of all groups and post-application of Groups III and IV were undertaken. SBS tests were performed. Ca/P ratio significantly increased after the applications. Both agent groups showed a significant decrease in SBS values compared to others. There was no correlation between SBS and Ca/P ratio changes. It can be said that CPP-ACP and resin infiltrant therapies enhance the tooth mineral content, but show lesser SBS values than the control and demineralization only groups.

The effects of different desensitizer agents on shear bond strength of orthodontic brackets after home bleaching: an in vitro study.

The aim of this study was to test the null hypothesis that no difference exists between shear bond strength values of control and bleaching plus desensitizer applied groups. A hundred freshly extracted human premolar teeth were randomly divided into five groups. Group I served as the control group with no bleaching application, while only bleaching was achieved in Group II. Desensitizer containing potassium nitrate-fluoride and casein phosphopeptide amorphous calcium phosphate were applied in Groups III and IV, after bleaching respectively. A bleaching agent containing amorphous calcium phosphate was used in Group V. Shear bond strength tests were carried out using a universal testing machine (Instron Corp., Norwood, MA, USA). Remnant adhesive on the teeth and brackets was examined to score the adhesive remnant index. Kruskal-Wallis and Chi-Square tests were used for statistical analysis of the data. Statistically significant differences were found among the groups for shear bond strength values (p<.001). The shear bond strength of Group III (8.0±2.2 MPa) was significantly lower than the other groups (p<.05). The highest shear bond strength values were found for Group I (13.6±3.7 MPa) and Group IV (12.8±4.0 MPa). No statistically significant difference was observed between Group II (10.0±2.7 MPa) and Group V (10.8±2.9 MPa). The differences between adhesive remnant index scores of the groups were not statistically significant. Casein phosphopeptide amorphous calcium phosphate gel application showed a similar shear bond strength value to the control group, while shear bond strength values decreased after using other desensitizers.

Toward a Single-Dose Vaccination Strategy with Self-Encapsulating PLGA Microspheres.

Poly(lactic-co-glycolic acid) (PLGA) microspheres have been widely examined for vaccine applications due to their attractive features of biocompatibility, biodegradability, ability to be internalized by antigen-presenting cells, and long-term antigen release. However, one of the major challenges for PLGA particle vaccines is the potential for antigen instability and loss of antigenicity and immunogenicity. To address this challenge, we have developed a new method of "self-healing" encapsulation in PLGA microspheres, where pre-made PLGA microspheres are loaded with protein antigens under aqueous conditions with minimal impact on their antigenicity and immunogenicity. In this report, we show that mice immunized with self-encapsulating PLGA microspheres in a prime-boost regimen generated significantly enhanced antigen-specific CD8α+ T cell and antibody responses, compared with mice immunized with free, soluble protein admixed with calcium phosphate gel, a widely used adjuvant. Furthermore, a single-dose of microspheres designed for >40 day sustained antigen release elicited robust cellular and humoral immune responses as efficiently as the prime-boost vaccinations with calcium phosphate gel. Overall, these results suggest excellent potential of our self-encapsulating PLGA microspheres as a vaccine platform for multiple-dose as well as single-dose vaccinations.

TREATMENT OF MUNICIPAL WASTEWATER WITH CALCIUM PHOSPHATE: A NEW PHYSICOCHEMICAL PURIFICATION STEP

An apatitic calcium phosphate gel (HaG) was elaborated and used to treat municipal wastewater in a physicochemical cycle prior to the standard biological degradation process. Preliminary laboratory batch experiments outlined the kinetics of heavy metal sorption by monitoring the concentrations found in filtered fractions as a function of treatment time. On site experiments were performed in a municipal wastewater treatment plant by derivation of real wastewater into an experimental tank. In this case, the sorption of organic and metal pollution was studied on the whole effluent. The solid and liquid phases were both characterized using elemental analysis, total and organic carbon, and thermal analysis of the solids collected. Results showed significant reductions in heavy metal contents of about 50 to 60% for main metals such as lead, aluminum and iron in the liquid phase. The concentrations went respectively from initial values of 0.07, 0.15 and 1.80 ppm to 0.04, 0.11 and 0.03 ppm in the treated waters for these elements. Organic matter also reacted with the HaG by adsorbing to the solid particles, with the contents of organic carbon increasing from zero to 80 g/Kg on the solids and decreasing from 130 ppm to 24 ppm in the liquid phase. This allows foreseeing improvements in the biological treatment process following this physicochemical purification step. The elemental analysis showed that up to 50 and 90 percent of the heavy metals could be removed from the effluent. The presence of the organic matter adsorbed on calcium phosphate was confirmed by thermal methods.

Zn release behavior of amorphous calcium phosphate and alginate gel composite

Event Abstract Back to Event Zn release behavior of amorphous calcium phosphate and alginate gel composite Tomohiro Uchino1, Tomomi Nakanome1 and Tomoya Mori1 1 Nihon University, College of Engineering, Japan Introduction: Some cements for bone substitute has an advantage on injectable and regardless of bone defect appearance. Amorphous calcium phosphate (ACP) is considered a precursor to bone hydroxyapatite (HAp; Ca10(PO4)6(OH)2)[1]. Zn is a trace element as bone formation[2]. Alginate gel is a non-toxic material that can serve as a medium for controlled active ingredients release[3][4]. In this study, we prepared injectable Zn-containing gel composites consisting of alginate and ACP. Then, we try to investigate the Zn release behavior from the composites in an environment of mimicking bone metabolism. The obtained samples were injected and immersed in an acetic acid buffer solution (AcBu) mimicking the peripheral environment of active osteoclasts or in a simulated body fluid (SBF: Kokubo’s solution) mimics the environment of active osteoblasts. After immersing the samples in AcBu or SBF solutions, the Zn release behavior and characterization of the samples were investigated. Materials and Methods: CaCl2∙H2O and NaH2PO4 solutions were mixed at a 1:1 molar ratio of Ca and P. The mixed solution was added to a stirred NaOH solution at less than 4ºC and a pH10. The precipitates were filtered, washed with acetone, and freeze dried. ZnSO4 solution and sodium alginate solution (Alg) were mixed. This solution was mixed with obtained ACP powder with an emulsion needle (AlgZn-Ca). For another preparation, the ACP powder and Alg were mixed first, and then, mixed with Zn solution (CaAlg-Zn). These AlgZn-Ca or CaAlg-Zn gel composite sample was injected into 30 cm3 of AcBu or SBF at 37ºC for 1, 3, and 7 days. Immersing for 1 and 3 days, 10 cm3 of immersed solutions were exchanged for new solution. After immersing 7 days, gel composite samples were dried at room temperature. Zn, Ca and P concentrations in AcBu and SBF before and after immersing the samples were measured. For alginate gel characterization, Zn or Ca containing alginate gel was synthesized by dropped Zn or Ca solution into alginate solution. Results and Discussion: The Zn release behavior of these gel composites is shown in Fig. 1. The Zn release rate of ZnAlg-Ca was slower than CaAlg-Zn in AcBu. Similarly, Ca and P were released from the composites in AcBu. After immersing ZnAlg-Ca in AcBu for 7days, 80% of Zn was released. In contrast, after immersed these samples in SBF for 7 days, less than 1% of Zn was released from these samples. The Zn release rate would be controlled by alginate cross-linked Zn2+. Alginate forms a gel with divalent cations (Ca2+, and Zn2+) as cross-linking points. From DTA measurement, exothermal peak was detected at 530ºC of Zn2+ containing gel, in contrast, the peak was detected at 700ºC of Ca2+ containing gel (Fig. 2). The ZnAlg-Ca sample formed alginate gel by Zn2+ would make Zn slower release. Conclusion: The alginate gel was effective for controlling Zn release and making injectable samples. The gel composite samples were expected to be a new controlled release injectable bone substitutes. JSPS KAKENHI Grant Number 26861688.

Allergen extract suspension for subcutaneous injection (Alustal®; Phostal®): a guide to its use for allergen-specific immunotherapy

Alustal® and Phostal® are injectable suspensions containing allergen extracts adsorbed onto aluminium hydroxide and calcium phosphate gels, respectively. Alustal® and Phostal® are indicated for use as subcutaneous allergen immunotherapy (SCIT) in children aged ≥5 years and adults who have type 1 allergies of a seasonal or perennial nature. SCIT with Alustal® or Phostal® was effective and generally well tolerated in clinical trials in patients with allergic symptoms induced by grass or tree pollens or house-dust mites. In general, allergic symptoms were improved and the use of symptomatic drug treatment was reduced, with some studies also showing improvements in health-related quality of life. Accelerated Alustal® dose-escalation schedules are available in some countries and will likely improve the convenience of SCIT for patients. Accelerated dose-escalation schedules (e.g. cluster build-up schedules and shortened conventional build-up schedules) were generally well tolerated in clinical trials.

Novel Nanostructured Zn-substituted Monetite Based Biomaterial for Bone Regeneration

A bone regeneration biomaterial must be biocompatible, osteoconductive and osteoinductive, and be gradually replaced by newly formed bone in the shorter time possible. Nanostructured materials, emulating bone composition and morphology, have shown great potential in bone repair because of their higher reactivity, faster reabsorption and improved biological behavior over microstructured materials. This work was aimed at developing a new biomaterial that meets the requirements for effective bone regeneration. Combination of elements with different solubility such as monetite, hydroxyapatite, amorphous calcium phosphate and silica gel, provided with the means to modulate the rate of material reabsorption of this novel biomaterial were Zn was found to be present as a partial substitution of Ca in the monetite lattice. The biomaterial was obtained by a hydraulic cementing reaction and was characterized by XRD, FTIR, NMR, chemical analysis, N2 adsorption porosimetry, Hg porosimetry, picnometry, SEM, TEM and evaluated in vitro and in vivo. Biomaterial showed a nanometric structure with a very high specific surface area (≈80 m2/g), high surface roughness and high intragranular porosity (50%) ranging from macro to nanopores. All of these are key features for a bone regeneration material. Solubility studies demonstrate the different solubility of its components and the release of Ca, P, Si and Zn. In vivo evaluation showed the effectiveness of the material to regenerate and to maintain 89 ± 9% of the volume of a critical size bone defect in sheep at 16 weeks. In the restored volume residual biomaterial was found to occupy 9 ± 5% of the space while newly formed trabeculae occupied 32 ± 6% of the space. The newly formed bone showed abundant vascularization and osteogenic activity. Biomaterial was estimated to have resorbed by 86 ± 7% with a reduction of 67 ± 8% in diameter and clear signs of cell-mediated resorption.

Poly(Epsilon-Lysine) Dendrons Tethered with Phosphoserine Increase Mesenchymal Stem Cell Differentiation Potential of Calcium Phosphate Gels

Calcium phosphates (CaP) are considered as biomaterials of choice for the treatment of critical-sized bone defects. Novel injectable CaP materials integrating poly(epsilon-lysine) generation 3 dendrons tethered with phosphoserine were obtained by sol-gel synthesis. This type of dendron was integrated to mimic the biochemical structure of noncollagenous proteins present in the forming osteoids during bone repair. Sol-gel synthesis was coupled with a dialysis process able to equilibrate the materials at a physiological pH value. Fourier transform infrared spectroscopy (FTIR) showed the successful retention of the dendrons after gel dialysis, whereas X-ray diffraction analysis demonstrated both the pH-tuned formation of a hydroxyapatite crystalline phase within the gel and the complete removal of ammonium nitrate deriving from the sol-gel reaction solvent. Scanning electron microscopy images confirmed the presence of crystalline domains in gels synthesized at pH 9.0. Injectability tests showed that the optimized formulations fulfilled the rheological properties required to minimally invasive surgical procedures. Cytotoxicity tests on osteoblast-like MG-63 cells as well as morphology and viability studies showed that the dendrons induced a significantly higher level of cell proliferation at early incubation time. Differentiation of the cell was also clearly enhanced at longer incubation time as demonstrated by both alkaline phosphatase activity and expression of typical markers. Altogether, the data from this work indicate the clinical potential of the osteoid-mimicking CaP cements in minimally invasive bone surgery.

Calcium Phosphate Sorbent for Environmental Application

Heavy metal pollution in soils, wastewater or fly ashes is a persistent environmental problem. This pollution in water or wastewater is an ongoing environmental problem and the rules to control and decrease this pollution are increasingly strict. The extreme toxicity of heavy metals even at low concentration and their bio-accumulation cause a lot of environmental problems. Minerals such as the calcium phosphate of general formula M10(XO4)6 Y2 with M a divalent cation, (XO4)3- a trivalent anion and Y- a monovalent anion are well know for trapping metal ions. The retention of heavy metals by calcium phosphate has been already widely studied in aqueous solutions.In this study, a low cost calcium phosphate gel (Ca-HA) synthesized from a calcium carbonate industrial waste was used as a sorbent for wastewater treatment. We have characterized this sorbent before and after use. The physical characterization showed a decrease of the specific surface area and density. The granulometry measurements showed an increase of the particles diameter explained by the sorption of pollutants (organic molecules). The presence of these molecules was confirmed by total and organic carbon measurement and thermal analysis. The elemental measurements confirmed also the heavy metal sorption by the Ca-HA. A calcination of the contaminated Ca-HA was carried out at different temperatures. After calcination the solid contained less organic molecules and heavy metals were concentrated in the matrix.