Tricalcium Phosphate Research Articles

Heat treatment of plasma sprayed tricalcium phosphate coatings deposited on substrate Ti-6Al-4V ELI

Heat treatment of plasma sprayed tricalcium phosphate coatings deposited on substrate Ti-6Al-4V ELI

Development and In Vitro Characterization of Antibiotic-Loaded Nanocarriers for Dental Delivery.

The aim of this research work was to formulate and evaluate ciprofloxacin hydrochloride-loaded nanocarriers for treating dental infections and bone regeneration. Periodontal infection is associated with inflammation, soft tissue destruction, and bone loss. The objective of the study was to extract β tricalcium phosphate (β-TCP) from coral beach sand using the hydrothermal conversion method and load these nanocarriers with ciprofloxacin hydrochloride. The developed drug-loaded nanocarriers were evaluated for various parameters. In vitro drug-loading studies showed the highest drug loading of 71% for F1 with a drug: carrier ratio compared to plain ciprofloxacin hydrochloride gel. β-TCP and nanocarriers were evaluated for powder characteristics and the results were found to have excellent and fair flowability. In vitro drug release studies conducted over a period of 5 days confirmed the percentage drug release of 96% at the end of 120 h. Nanocarriers were found to be effective against S. aureus and E. coli showing statistically significant antibacterial activity at (* p < 0.05) significant level as compared to plain ciprofloxacin hydrochloride gel. The particle size of β-TCP and nanocarriers was found to be 2 µm. Fourier transform infra-red studies showed good compatibility between the drug and the excipients. Differential scanning calorimetry studies revealed the amorphous nature of the nanocarriers as evident from the peak shift. It is obvious from the XRD studies that the phase intensity was reduced, which demonstrates a decrease in crystallinity. Nanocarriers released the drug in a controlled manner, hence may prove to be a better option to treat dental caries as compared to conventional treatments.

Properties of Coatings Based on Calcium Phosphate and Their Effect on Cytocompatibility and Bioactivity of Titanium Nickelide

Coatings based on calcium phosphate with thicknesses of 0.5 and 2 μm were obtained by high-frequency magnetron sputtering on NiTi substrates in an argon atmosphere. The coating was characterized using X-ray diffraction, scanning electron microscopy, atomic force microscopy, and in vitro cytocompatibility and bioactivity studies. A biphasic coating of tricalcium phosphate (Ca3(PO4)2) and hydroxyapatite (Ca10(PO4)6(OH)2) with a 100% degree of crystallinity was formed on the surface. The layer enriched in calcium, phosphorus, and oxygen was observed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Scanning electron microscopy showed that the surface structure is homogeneous without visible defects. The 2 µm thick coating obtained by sputtering with a deposition time of 4 h and a deposition rate of 0.43 µm/h is uniform, contains the highest amount of the calcium phosphate phase, and is most suitable for the faster growth of cells and accelerated formation of apatite layers. Samples with calcium phosphate coatings do not cause hemolysis and have a low cytotoxicity index. The results of immersion in a solution simulating body fluid show that NiTi with the biphasic coating promotes apatite growth, which is beneficial for biological activity.

DFT theoretical and experimental studies unraveling the structural and electronic properties of niobium doped calcium apatite ceramics

Calcium apatite ceramics consisting of a biphasic structure of hydroxyapatite (HAP) and tricalcium phosphate (β-TCP) have been widely explored by biomedical communities for hard-tissue engineering applications, especially bone replacement as it has the potential to mimic the properties of the natural bones. Doping of cations in the hydroxyapatite (NbHAP) is expected to promote the alkaline phosphatase activity and thereby generation of new bone, which, however, depends on its structural and electronic properties. In the present investigation, the variation in the structural and electronic properties of NbHAP prepared by the chemical precipitation method is determined theoretically by employing density functional theory (DFT) using the B3LYP functional method in the Gaussian 09 package program and experimentally using various characterization tools. The experimental investigation by X-ray diffraction (XRD) studies revealed notable variation in the β-TCP content in NbHAP when compared to the pristine HAP, while the Inductively Coupled Plasma spectroscopic results revealed the presence of Nb ions in doped HAP and along with the percentage increase in β-TCP content in NbHAP by Ca/P molar ratio variation, when compared with the HAP system. In addition, experimentally determined Raman spectroscopic values revealed the formation of substitution-type solid solutions in the NbHAP system. The doping of niobium ions was shown to cause noticeable variations in the reactivity indices, as indicated by a number of electronic characteristics that were calculated using DFT. Furthermore, variations in the theoretical parameters such as dipole moment, polarizability, and electric susceptibility revealed that NbHAP is better bioceramic material for hard-tissue engineering applications in comparison to HAP.

Novosphingobium kaempferiae sp. nov., a phosphate-solubilizing bacterium isolated from stem of Kaempferia marginata Carey.

A Gram-stain-negative, aerobic, rod-shaped, non-spore-forming and yellow-pigment-producing bacterium, designated as Sx8-5T, was isolated from stem tissue of Kaempferia marginata Carey in Kanchanaburi Province, Thailand. The strain exhibited tricalcium phosphate solubilizing activity. Its taxonomic position was investigated using a polyphasic approach. Sx8-5T grew at 25-37 °C (optimum 30 °C), pH 6-9 (optimum 7) and with 0 and 1% NaCl (optimum 0 %). According to the 16S rRNA gene phylogeny, Sx8-5T represents a member of genus Novosphingobium and shared the highest sequence similarities to Novosphingobium barchaimii LL02T of 99.4 % and shared sequence similarities with other species of the genus Novosphingobium of less than 99.4 %. The whole-genome size was 5.7 Mb, comprised of one contig, with a DNA G+C content of 66 %. The average nucleotide identity using BLASTn (ANIb) or MUMMER (ANIm) values for whole genome comparisons between Sx8-5T and Novosphingobium barchaimii LL02T and six closely related type strains were 72.33-82.14 % and 83.82-87.38 %, respectively, and the digital DNA-DNA hybridization (dDDH) values ranged from 21.0 to 28.6% when compared with the type strains of the members of the genus Novosphingobium. Major fatty acids were summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), C16 : 0 and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), respectively. Polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, unidentified phospholipids and unidentified polar lipids. The major isoprenoid quinone was Q-10. According to results obtained using a polyphasic approach, Sx8-5T represents a novel species of the genus Novosphingobium, the name Novosphingobium kaempferiae sp. nov. is proposed. The type strain is Sx8-5T (=JCM 35076T =TBRC 15600T).

Mg2+, Sr2+, Ag+, and Cu2+ co‐doped β‐tricalcium phosphate: Improved thermal stability and mechanical and biological properties

Abstractβ‐tricalcium phosphate (β‐TCP, β‐Ca3(PO4)2) is an attractive biomaterial for bone repair applications. However, its sintering and mechanical properties are limited by a problematic phase transition to α‐TCP. Cationic doping of β‐TCP is able to postpone the formation of α‐TCP allowing higher sintering temperatures and better mechanical properties. The co‐doping of β‐TCP with Mg2+ and Sr2+ has already been studied in detail, but the addition of antibacterial cations (Ag+ and Cu2+) on the Mg–Sr β‐TCP co‐doped composition remains unexplored. Thus, two co‐doped β‐TCP compositions were realized by aqueous precipitation technique without any secondary phase and compared with undoped β‐TCP: Mg–Sr (2.0–2.0 mol%) and Mg–Sr–Ag–Cu (2.0–2.0–0.1–0.1 mol%). Differential thermal analysis and dilatometry analyses showed a slight decrease of the β‐TCP → α‐TCP phase transition temperature for the Mg–Sr–Ag–Cu (2.0–2.0–0.1–0.1% mol) composition as compared to the Mg–Sr (2.0–2.0 mol%). However, both exhibited much higher transition temperatures than undoped β‐TCP. The addition of Ag+ and Cu2+ slightly reduces the grain size after sintering compared to the Mg–Sr (2.0–2.0 mol%) and the undoped compositions. The co‐doped compositions also exhibited improved mechanical properties, specifically a higher Vickers hardness and elastic modulus. Finally, cell proliferation assays showed that the presence of dopants, even Ag+ and Cu2+, does not affect the survival and proliferation of cells. Thus, the use of Mg2+, Sr2+, Ag+, and Cu2+ co‐doped β‐TCP could be very promising for biomedical applications due to the improvements of these dopants on the thermal stability and mechanical and biological properties.

Isolation, Identification, and Characterization of Phosphate-Solubilizing Bacteria from Tunisian Soils

Soil microorganisms play an important role in maintaining natural ecological balance through active participation in carbon, nitrogen, sulfur, and phosphorous cycles. Phosphate-solubilizing bacteria (PSB) are of high importance in the rhizosphere, enhancing the solubilization of inorganic phosphorus complexes into soluble forms available for plant nutrition. The investigation of this species of bacteria is of major interest in agriculture, as they can be used as biofertilizers for crops. In the present study, 28 isolates of PSB were obtained after the phosphate enrichment of soil samples from five Tunisian regions. Five PSB species were identified by 16S rRNA gene sequencing including Pseudomonas fluorescens, P. putida, and P. taiwanensis, Stenotrophomonas maltophilia, and Pantoea agglomerans. Solid and liquid Pikovskaya's (PVK) and National Botanical Research Institute's (NBRIP) media containing insoluble tricalcium phosphate were used for the evaluation of the phosphate solubilization ability of the bacterial isolates by two methods: visual evaluation of the solubilization zone around colonies (halo) and determination of solubilized phosphates in liquid medium by the colorimetric method of the vanado-molybdate yellow. Based on the results of the halo method, the isolate of each species that showed the higher phosphate solubilization index was selected for evaluation of phosphate solubilization by the colorimetric method. In the liquid media, the bacterial isolates showed phosphate solubilization ranging from 535.70 to 618.57 µg mL-1 in the NBRIP medium, and 374.20 to 544.28 µg mL-1 in the PVK medium, with the highest values produced by P. fluorescens. The best phosphate solubilization ability and higher reduction in broth pH, which indicates higher organic acid production, were achieved in NBRIP broth for most of the PSB. Strong correlations were observed between the average capability of PSB to solubilize phosphates and both the pH and total phosphorous content in the soil. The production of the hormone indole acetic acid (IAA), which can promote plant growth, was observed for all five PSB species. Among them, P. fluorescens obtained from the forest soil of northern Tunisia showed the highest production of IAA (50.4 ± 0.9 µg mL-1).

Evaluation of efficacy of various remineralizing agents on artificially demineralized human enamel – An in-vitro study

Currently much research revolves around remineralization as incidence of white spot lesions in patient undergoing orthodontic treatment is 2-96%. The objective of this study was to find out the efficacy of Casein phosphopeptide-amorphous calcium fluoride phosphate (CPP-ACFP), Functionalized tricalcium phosphate (f-TCP), Calcium sodium phosphosilicate (CSPS), Calcium sucrose phosphate (CSP), Nano hydroxyapatite (nHAP) and Fluoride (F) in remineralizing artificially demineralized enamel and DIAGNOdent and scanning electron microscope were used to record the changes. The study included 140 extracted premolars which were divided into 7 groups in which 6 were experimental groups: I (CPP-ACPF), II (f-TCP), III (CSPS), IV (CSP), V (nHAP), VI (F) and 1 control group: VII (C). All the samples were evaluated using DIAGNOdent at the baseline, post demineralization and post remineralization. One sample was randomly selected from each group for evaluation using SEM. Statistical analysis has shown that all the groups had higher amount of remineralization except control group. CSPS showed maximum remineralization. All the artificially demineralized samples treated with remineralizing agents for 3 weeks reduced the severity of lesions by forming calcific deposits. However CSPS showed marginally more amount of remineralization than others.

Isolation of Phosphate-Solubilizing Microorganisms and the Formulation of Biofertilizer for Sustainable Processing of Phosphate Rock.

As phosphorus (P) bioavailability is limited in arable lands, chemical fertilizers are being used by farmers to increase crop production. Phosphate-solubilizing microorganisms (PSMs) increase the bioavailability of sparingly soluble inorganic and organic soil phosphorus. Therefore, the current study was an effort to evaluate the phosphate-solubilizing efficiency of PSMs using tricalcium phosphate (TCP) and Eppawala rock phosphate (ERP). The efficiency of phosphate solubilization by a series of identified isolates was compared using TCP (5 g L-1) and ERP (5 g L-1) as a P source in Pikovskava's broth. Twelve microbial isolates that showed a higher efficiency in phosphate solubilization were selected for the production of the biofertilizer. The isolate F10 in ERP broth was characterized by the highest significant level of available phosphorus (896.98 ± 10.41) mg L-1, followed by F5 (Aspergillus sp.) in TCP broth 991.43 ± 1.37 mg L-1. A pot trial was carried out by using Capsicum annuum L. as the test plant in two soil conditions: sterilized soil and non-sterilized soil with six treatments and four replicates. The significantly highest plant height, leaf length, and width were shown by chili plants treated with the formulated biofertilizer. Therefore, the application of native PSMs appeared to be an efficient method of solubilizing sparingly soluble P compounds into plant-available forms.

Rheological Behavior and Printability Study of Tri-Calcium Phosphate Ceramic Inks for Direct Ink Writing Method

In the biomedical industry, tricalcium phosphate is a bioceramic substance that is frequently employed in the fabrication of scaffolds and bone structures. Fabrication of porous ceramic structures using conventional manufacturing techniques is very challenging because of the brittle nature of the ceramics, which has led to a newly adapted direct ink writing additive manufacturing method. This work investigates the rheology and extrudability of TCP inks to produce near-net-shape structures. Viscosity and extrudability tests found that stable TCP: Pluronic ink of 50 vol.% was more reliable compared to other tested inks prepared from a functional polymer group polyvinyl alcohol. A line study was carried out to identify the printing parameters suitable for printing structures from the selected ink with lesser dimensional error. Printing speed 5 mm/s and extrusion pressure 3 bar was found suitable to print a scaffold through a nozzle of 0.6 mm, keeping the stand-off distance equal to the nozzle diameter. The printed scaffold was further investigated for its physical and morphological structure of the green body. A suitable drying behavior was studied to remove the green body without cracking and wrapping before the sintering of the scaffold.

A Systematic Review on Electrospun Polymer Nanocomposites Used for Bone Tissue Engineering

Trauma, disease and various pathological conditions of bone may lead to the need of bone grafts and their substitutes to the affected patients. Bone grafting is a surgical process that repairs, rebuilds or replaces the lost bone. The main function of bone grafts is to induce osteoconduction, osteoinduction and osteogenesis along with providing the structural support for adherence and proliferation of bone cells at the implanted site. Bone grafts are available in a variety of substances broadly categorized into natural and synthetic grafts. The gold standard is autografts, where the bone from a person’s own body is used for implant. Other than autogenous grafts, allografts, xenografts and various isolated or polymer composites of calcium phosphate, tricalcium phosphate, calcium sulfate and hydroxyapatite are available. Zeroing in on an ideal bone graft for a specific clinical situation is a surmounting task as all grafts do not have the same properties. Hence, this review presents a deep study on the history of bone developments in the field of tissue engineering. It presents a thorough account on the natural and synthetic biodegradable electrospun polymers used for scaffolding purpose to engineer the bone.

Study on warpage deformation of micro extrusion 3D Printing Bone Tissue Engineering Scaffold and Its Optimization Method

Spinal degeneration is a major disease that affects human health. Titanium alloy, PECK, and other nondegradable materials are currently used in interbody fusion cages. It is important to develop a biodegradable biomaterial. Taking the warpage analysis in micro extrusion 3D printing of tricalcium phosphate (TCP) and polycaprolactone (PCL) mixed materials as an example, the theoretical model of 3D printing part deformation is established and studied, the influence of different stress resultant forces on warpage is analyzed. The influence of layer height, ambient temperature, and other process parameters on the warpage of the finished product is quantitatively analyzed. It is proposed to increase the printing temperature appropriately and print layer thickness. The printing warpage can be reduced by reducing the end face length.

Functional Properties of Salted Duck Egg Powder with Maltodextrin and Tricalcium Phosphate Incorporation as Anticaking Agents

The protein content in egg contributes effectively to the fulfilment of nutrients in daily life at an affordable price and acceptable organoleptic properties. This study aimed to investigate the effect of anti-caking agent addition (maltodextrin and tricalcium phosphate) on the quality and functional properties of salted duck egg powder. Addition of 2% maltodextrin increased the moisture content in salted duck egg powders as much 36% compared to the control. 2% TCP incorporation decreased the moisture content up to 54%, could not maintain the emulsion stability, but it increased the emulsion activity. There were no significant differences (p &lt; 0.05) on the parameter of foaming capacity and foaming stability. Anticaking agent maltodextrin and TCP did not affect the water holding capacity of all four salted duck eggs powder. However, maltodextrin addition slightly increased the oil holding capacity. Due to the functional properties of emulsification, foaming, water and oil binding, salted duck egg powders are potentially utilized for the complementary of a large number of food products with its characteristics of longer shelf life and specific flavor.

Characterization and evaluation of native rhizobacteria isolated from Meloidogyne incognita-infected tomato (Solanum lycopersicum)

Three native rhizobacteria, IRh9, IRh10 and IRh15, were isolated from nematode-infected tomato (Solanum lycopersicum L.) rhizosphere were characterized and evaluated for their efficacy against root-knot nematode (RKN), Meloidogyne incognita infecting tomato crop under pot conditions in the protected structure environment during 2020–21 at Centre for Protected Cultivation technology (CPCT), ICAR-Indian Agricultural Research Institute, New Delhi. Based on 16S rRNA sequences, IRh9, IRh10, and IRh15 showed &gt; 98% homology with Bacillus licheniformis, Priestia megaterium and Pseudomonas putida, respectively. Compared to the control, the penetration of root-knot nematode in tomato roots was reduced by &gt;50% under pot conditions through inoculation of these bacteria. Characterization through gas chromatography-mass spectrometry analysis revealed 30 different volatile organic compounds from these rhizobacteria. Among them, 19 compounds were identified from P. megaterium IRh10, followed by 16 compounds each from B. licheniformis IRh9 and P. putida IRh15. Furthermore, among the detected volatile organic compounds, acetic acid, hexadecane, hexadecanoic acid, octadecanoic acid, 1-decene and 9-octadeconoic acid are reported to possess nematicidal properties. Additional characterization of plant growth promotion traits associated with these rhizobacteria revealed that P. megaterium IRh10 and P. putida IRh15 produced indole acetic acid, while B. licheniformis IRh9 and P. megaterium IRh10 produced ammonia, but only P. putida IRh15 could solubilize the tricalcium phosphate under laboratory conditions. Among the 35 substrates studied, P. megaterium IRh10 utilized most (12), followed by B. licheniformis IRh9 and P. putida IRh15, which were able to use 11 and 8 substrates, respectively. The study showed that B. licheniformis IRh9, P. megaterium IRh10 and P. putida IRh15 are potential candidates for combating M. incognita infestation in tomato crops.

Effect of moisture on the reactivity of alpha-tricalcium phosphate

The ability of the high-temperature polymorph of tricalcium phosphate, α-TCP, to hydrolyse to calcium-deficient hydroxyapatite underlies many developments in the field of synthetic bone grafts, including calcium phosphate cements, foams, and self-setting inks. The objective of the present work was to investigate the effect of humidity on α-TCP powder reactivity. The results showed that a 3-week incubation at high relative humidity (80%) had no impact on reactivity, but, as the incubation was prolonged, the powder started to hydrolyse. This reactivity was associated to the presence of defects and to an amorphous phase induced during powder milling. Moisture studies performed under static/dynamic conditions gave comparable water adsorption percentages. The dynamic studies further proved irreversible water sorption, indicating that some water molecules reacted with the powder after short incubation times. Taken together, these results demonstrate that, although α-TCP powder adsorbs water from moisture immediately, the impact on reactivity appears only after several weeks of storage.

Ceramic Materials in Na2O-CaO-P2O5 System, Obtained via Heat Treatment of Cement-Salt Stone Based on Powder Mixture of Ca3(C6H5O7)2∙4H2O, Ca(H2PO4)2∙H2O and NaH2PO4

Ceramic materials in Na2O-CaO-P2O5 system were obtained by firing cement-salt stone made from pastes based on powder mixtures including calcium citrate tetrahydrate Ca3(C6H5O7)2∙4H2O, monocalcium phosphate monohydrate (MCPM) Ca(H2PO4)2∙H2O and/or sodium dihydrogen phosphate NaH2PO4. The phase composition of the obtained samples of cement-salt stone after adding water, hardening and drying included brushite CaHPO4∙2H2O, monetite CaHPO4 and also unreacted Ca3(C6H5O7)2∙4H2O, Ca(H2PO4)2∙H2O and/or NaH2PO4. The phase composition of ceramics in Na2O-CaO-P2O5 system obtained by firing cement-salt stone was formed due to thermal conversion of hydrated salt and heterophase reactions between components presented in samples during firing. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O and Ca(H2PO4)2∙H2O after firing at 900 °C included β-calcium pyrophosphate (CPP) β-Ca2P2O7. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O, and NaH2PO4 after firing at 900 °C included β-sodium rhenanite β-CaNaPO4. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O, Ca(H2PO4)2∙H2O and NaH2PO4 after firing at 900 °C included β-Ca2P2O7, β-CaNaPO4, double calcium-sodium pyrophosphate Na2CaP2O7, and Na-substituted tricalcium phosphate Сa10Na(PO4)7. Obtained ceramic materials in Na2O-CaO-P2O5 system including biocompatible and biodegradable phases could be important for treatments of bone tissue defects by means of approaches of regenerative medicine.

Tricalcium Phosphate as a Bone Substitute to Treat Massive Acetabular Bone Defects in Hip Revision Surgery: A Systematic Review and Initial Clinical Experience with 11 Cases

The use of tricalcium phosphate (TCP) as a bone substitute is gaining increasing interest to treat severe acetabular bone defects in revision total hip arthroplasty (rTHA). The aim of this study was to investigate the evidence regarding the efficacy of this material. A systematic review of the literature was performed according to the PRISMA and Cochrane guidelines. The study quality was assessed using the modified Coleman Methodology Score (mCMS) for all studies. A total of eight clinical studies (230 patients) were identified: six on TCP used as biphasic ceramics composed of TCP and hydroxyapatite (HA), and two as pure-phase ceramics consisting of TCP. The literature analysis showed eight retrospective case series, of which only two were comparative studies. The mCMS showed an overall poor methodology (mean score 39.5). While the number of studies and their methodology are still limited, the available evidence suggests safety and overall promising results. A total of 11 cases that underwent rTHA with a pure-phase ceramic presented satisfactory clinical and radiological outcomes at initial short-term follow-up. Further studies at long-term follow-up, involving a larger number of patients, are needed before drawing more definitive conclusions on the potential of TCP for the treatment of patients who undergo rTHA.

Кальцийфосфатные брушитные цементы из замещенного трикальцийфосфата Ca3(PO4)2, армированные силикатным стекловолокном

The reinforcement of reaction hardening phosphate materials (phosphate cements) for bone implants, based on isomorphically cation- (Na+, K+) and anion- (SiO44-, SO42-) substituted tricalcium phosphate (β and α-TCP, Ca3(PO4)2), that are reinforced with silicate (basalt-based) fiberglass, is considered. The obtained materials were characterized by the XRD and SEM methods, mechanical compression tests were carried out, the setting times of cements were determined, changes in the pH of the aqueous medium in contact with the cements under study were measured. Microstructure analysis has been shown that the surface of the reinforcing fiber in contact with the matrix of hardening cement is partially corroded with the formation of phosphate microparticles on it. By pH-metry it was found that the samples during prolonged contact with water do not significantly change the pH value of the aquatic environment, which remains in the nearly neutral range from 5 to 7.5, favorable for further biological tests.

Comparative evaluation of prevention of demineralization of artificial enamel caries treated with two fluoride varnishes and 38% SDF in primary teeth: an in vitro study

BackgroundThis study aimed to compare the effect of Clinpro™ White varnish containing 5% sodium fluoride (NaF) and functionalized tricalcium phosphate, MI varnish containing 5% NaF and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and 38% Silver diamine fluoride (SDF) in preventing demineralization of treated white spot lesions (WSLs) in enamel of primary teeth.MethodsForty-eight primary molars with artificial WSLs were allocated into four groups as follows: Group 1: Clinpro white varnish, Group 2: MI varnish, Group 3: SDF, and Group 4: control (no treatment). The three surface treatments were applied for 24 h and then enamel specimens were subjected to pH cycling. Thereafter, the mineral content of specimens was evaluated by Energy Dispersive X-ray Spectrometer and the lesion depth was assessed via Polarized Light Microscope. One-way ANOVA followed by Tukey’s post hoc test were used at p ≤ 0.05 to identify significant differences.ResultsInsignificant difference in mineral content was observed among treatment groups. Treatment groups exhibited significantly higher mineral content compared to control except for Fluoride (F). MI varnish showed the highest mean calcium (Ca) ion content (66.57 ± 0.63), and Ca/P (2.19 ± 0.11), followed by Clinpro white varnish, and SDF. MI varnish also displayed the highest phosphate (P) ion content (31.46 ± 0.56), followed by SDF (30.93 ± 1.02), and Clinpro white varnish (30.53 ± 2.19). Fluoride content was highest in SDF (0.93 ± 1.18), followed by MI (0.89 ± 0.34) and Clinpro (0.66 ± 0.68) varnishes. Significant difference in lesion depth was observed among all groups (p < 0.001). The lowest mean lesion depth (µm) was found in MI varnish (226.23 ± 44.25) which was significantly lower than Clinpro white varnish (285.43 ± 44.70), SDF (293.32 ± 46.82), and control (576.69 ± 42.66). Insignificant difference in lesion depth was found between SDF and Clinpro varnish.ConclusionsIn primary teeth, WSLs treated with MI varnish displayed better resistance to demineralization compared to WSLs treated with Clinpro white varnish and SDF.

Recycling of bone ash from animal wastes and by‐products in the production of novel cements

AbstractThe purpose of this research is to demonstrate the utilization of animal wastes and by‐products in the production of low‐energy and low‐CO2 clinkers and cements in order to preserve natural resources, such as limestone, while reducing CO2 emissions released from the cement manufacturing process and reducing potential health risk to the world population (such as bovine spongiform encephalopathy or other health issues…). Pure calcium sulfoaluminate clinker was produced with calcium hydroxide, aluminum hydroxide, and calcium sulfate hemihydrate; followed by additional clinkers produced from substituting calcium hydroxide with bone ash (from 0 to 100% of the calcium hydroxide replaced). The final clinkers contained various amounts of ye'elimite, calcium aluminate phases, as well as tricalcium phosphate, depending on the firing temperature. Finally, some preliminary results on the hydration process and compressive strength are provided for the production of these binders.