Calcium Hydroxide Slurry Research Articles

Modeling of calcium phosphate based on an LCD 3D printer using brushite and calcium hydroxide

There is demand for the development of highly functional and flexible bone fillers to treat bone defects. This research aimed to fabricate calcium phosphate implants with a flexible porous design and sufficient compressive stress using a three-dimensional 3D printer. A mixed slurry of dicalcium phosphate, calcium hydroxide, photopolymerized resin, and polyethylene glycol (PEG) was prepared using a planetary ball mill. The slurry was formed into a porous model using a stereolithography-type 3D printer. Upon sintering, the resin and PEG evaporated and/or combusted, yielding a β- tricalcium phosphate (TCP) molding with porosity. This study proposes a novel method for freely molding calcium phosphate implants.

Particle Size of Calcium Hydroxide Prepared by Wet Digestion: Influencing Factors and Mechanism

AbstractThe wet dissolution process of lime is an effective approach for synthesizing calcium hydroxide. Process parameters and additives exert influence on the product particle. Among the process parameters, lime particle size, reaction temperature, and time have a significant impact on product particle size, followed by liquid‐solid ratio and stirring speed. The experiment proved that reaction time affects product particle size by affecting the crystal growth, while other process parameters affect the particle size by affecting the ion diffusion behavior. In terms of inorganic additives, Ca(OH)2 has minimal effect on product particle size; however, NaOH and CaCl2 can significantly enhance it with a greater dose leading to a larger increase. The experiment proved that Ca(OH)2, NaOH, and CaCl2 influence particle size through their impact on ion diffusion behavior. Regarding organic additives, soluble starch exhibits the greatest effect on product size followed by triethanolamine and polyvinylpyrrolidone K30. The experiment proved that soluble starch, triethanolamine, and polyvinylpyrrolidone K30 affect product particle size by influencing its crystallization position. Finally, an ultrafine slurry of calcium hydroxide was prepared using the lime wet digestion method based on the aforementioned research, with particle size distribution characterized by D10, D50, and D90 values of 0.303, 1.750, and 4.534 µm respectively.

Post-operative Pain after Photo-Active Disinfection (PAD) Supplemented Single Visit Root Canal Treatment in Teeth with Symptomatic Apical Periodontitis

Objective: To observe the incidence of post-operative pain after single-visit Non-Surgical Endodontic Therapy (NSET) in teeth with symptomatic apical periodontitis disinfected with Photo-Activated Disinfection (PAD). Methods: Single-rooted teeth (N=30) with pulp necrosis and symptomatic apical periodontitis were included. Subsequent to chemo mechanical preparation, the teeth were randomly distributed into two groups: group I (n=15) which received calcium hydroxide slurry as an intracanal medicament and group II (n=15) which received PAD and obturation in the same visit. Postoperative pain was recorded at 4, 24, 48 and72 hours using a visual analog pain scale. One-way analysis of variance post hoc Tukey test was used to compare the score. Results: There was a significant reduction in pain after instrumentation in Groups I and II. The pain reduction was more in group I as compared to group II at 4 hours. There was no statistically significant difference seen in both the groups at 24, 48 and 72 hours postoperatively. Conclusion: Application of PAD as an adjunct in single visit NSET has no noticeable difference in pain perception when compared with the use of calcium hydroxide interim dressing in two visits NSET.

Investigation on the Removal of Carbon Dioxide Exhausted from Industrial Units in a Lab-Scale Fluidized Bed Reactor

In this study, CO2 removal efficiency from flue gas was investigated in a fluidized bed reactor under semi-dry conditions. A lab-scale fluidized bed reactor, filled with inert glass beads, was used to investigate the effect of operating parameters on the CO2 removal efficiency using calcium hydroxide slurry as the absorbent. The Taguchi design method was used to design the experiments. The maximum inlet concentration of CO2 was 3 vol%. The most important factors were the reaction surface area, inlet gas velocity, inlet CO2 concentration, absorbent solution flow rate, inlet gas temperature and calcium hydroxide slurry concentration. The experimental results indicated that the CO2 removal efficiency increased when increasing the effective surface area of the reaction. Moreover, the removal efficiency increased by decreasing the input gas flow rate and inlet CO2 concentration. By performing experiments under optimum conditions, the maximum obtained CO2 removal efficiency was 79%. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Effect of Additives to Improve Calcium-Based Sorbents in Semi-Dry Flue Gas Desulphurization

Semi-dry flue gas desulfurization (FGD) technology is used by some coal-based power plants to remove sulfur dioxide from flue gas. In semi-dry FGD systems, SO2 is removed by calcium-based sorbents in a reactive spray dryer, but the level of desulfurization is lower than in wet FGD systems. This work evaluates the effects of seven additives in the desulfurization of the flue gas: magnesium hydroxide, ammonium nitrate, ammonium acetate, ammonium phosphate, sodium hydroxide, citric acid, and urea. Slurries with calcium hydroxide concentrations of 10 and 20 wt% containing 2 and 4 wt% of an additive were applied in the removal of SO2. Additives containing ammonium intensified the removal of SO2 and increased the yield of the reaction. The SO2 content in the flue gas reduced by 73.8% when applying a slurry containing 4 wt% of ammonium nitrate and 10 wt% of Ca(OH)2. The use of this slurry increased the removal of SO2 by 13.5% when compared to the best result obtained using calcium hydroxide slurry without any additive.

Dry biodetoxification of acid pretreated wheat straw for cellulosic ethanol fermentation

BackgroundThe efficient removal of toxic inhibitors from pretreated lignocellulose biomass is crucially important for consequent cellulosic ethanol fermentation. A. resinae ZN1 biodetoxifies all toxic inhibitors at the neutral pH of 4–6, and the neutralization of acid catalyst in the pretreated lignocellulose is required. However, aqueous alkaline solutions such as sodium hydroxide solution and calcium hydroxide slurry are used which generate several difficulties.ResultsIn this study, a dry biodetoxification method was investigated using dry calcium carbonate (CaCO3) powder as an acid-neutralizing reagent to avoid the use of an aqueous alkaline solution. Dry biodetoxification provides a mild and stable pH without the generation of phenolic compounds. The acid pretreated and dry biodetoxified wheat straw was used as the feedstock of ethanol fermentation and the same performance with the wet biodetoxification using aqueous Ca(OH)2 slurry. The 72 g/L or 9.1% (v/v) of ethanol produced from wheat straw was very close to that of ethanol from corn starch.ConclusionsDry biodetoxification provided a practical method to simplify the process of conventional wet biodetoxification to reduce the time, cost and labor.

Influence of the calcium hydroxide paste vehicle on penetration into lateral canals

Objective: The aim of this study was to use Micro computed tomography (micro-CT) to evaluate the influence of the type of vehicle associated with calcium hydroxide on its ability to penetrate simulated lateral canals. Material and methods: 30 acrylic blocks with simulated lateral canals comprising apical, middle and cervical thirds were used in the in vitro study. The blocks were divided into 3 groups (n = 10) according to the type of vehicle used (chlorhexidine, distilled water and propylene glycol) in the calcium hydroxide slurry, which was inserted in the respective group of simulated canals with a K# 30 file and then agitated with an ultrasonic tip. The blocks were scanned by micro-computed tomography (micro-CT) before and after insertion of the medication. The images obtained were reconstructed and analyzed to obtain the initial volume of lateral canals and the volume of medication that penetrated into them. Results: In the intragroup analysis, both distilled water and chlorhexidine 2% were observed to present statistical difference in all thirds of the canal. Propylene glycol showed no intragroup difference. In the inter-group analysis, the propylene glycol paste presented higher values of penetration into the simulated lateral canals than the other groups (p <0.05). Conclusion: Propylene glycol used as vehicle of the calcium hydroxide paste provided better penetration results in simulated lateral canals. KeywordsEndodontics; Calcium hydroxide; Propylene glycol.

Calcium carbonate chain-like nanoparticles: Synthesis, structural characterization, and dewaterability

In the present study, we demonstrate a simple technique to synthesize calcium carbonate chain-like nanoparticles with high aspect ratios; we introduced CO2 gas into aqueous slurry of calcium hydroxide (lime milk) with addition of a small amount of lime milk during the reaction. Primary particle structures and agglomeration states of the chain-like particles were analyzed in detail and compared with those of spheroidal particles synthesized by a carbonation reaction without lime milk addition. The technique to fabricate anisotropic nanoparticles will broaden the applications of calcium carbonate. On the other hand, chain-like particles entangled with each other to form larger and fluffier agglomerates with sporadic pores. It was found that the slurry of chain-like particles showed much higher dewaterability (solid-liquid separation efficiency). Several properties of the filtered and dried cakes were investigated to decipher the mechanism of dewaterability. The novel technique to increase dewaterability without using any additives, such as surfactants, may expand the designing of nanoparticle manufacturing processes.

The Effect of Long-term Dressing with Calcium Hydroxide on the Fracture Susceptibility of Teeth

IntroductionCalcium hydroxide has been widely used to treat immature teeth to achieve periodontal healing and to promote the formation of an apical barrier. However, retrospective clinical studies have shown a high incidence of cervical root fractures with long-term calcium hydroxide dressing. The alkalinity of calcium hydroxide has been suggested to weaken the root. In vitro studies using ovine teeth show conflicting results on fracture strength of dentine, although different commercial products may have influenced the results. The purpose of this study was to investigate the effects of 2 commercial products used in prior studies (Calasept Plus and UltraCal XS), as well as a new product (Calmix) that uses a nonaqueous vehicle that allows for a higher pH, on the fracture strength of dentine over time. MethodsA total of 330 lamb incisor teeth were collected and the canals prepared so that 3 commercial calcium hydroxide products as well as a positive control of pure calcium hydroxide slurry that filled the root canal from the open apex and a negative control of saline was tested. The teeth were loaded until fracture with a universal testing machine at time points 0, 3, 6, and 9 months and the force to fracture was calculated. The data were analyzed with Friedman analysis of variance and Mann-Whitney t tests. ResultsNo statistical differences were observed between the different calcium hydroxide products and the negative controls. ConclusionsThin and fragile roots could be the cause of fracture rather than the calcium hydroxide dressing.

Application of a calcium hydroxide slurry with metabolic modifier for control of hydrogen sulfide odors at the siesta key wastewater treatment plant

Application of a calcium hydroxide slurry with metabolic modifier for control of hydrogen sulfide odors at the siesta key wastewater treatment plant

Apexification with apical plug of MTA-report of cases

Back ground: Immature teeth with necrotic pulp and large periapical lesion are difficult to treat via conventional endodontic therapy. The role of materials such as calcium hydroxide and Mineral trioxide aggregate (MTA) are indispensable. These case reports present successful healing and apexification using MTA. Methods: The case reports present two cases with traumatized upper anterior teeth. The radiographic evaluation revealed open apices with blunderbuss canals; the canal was cleaned using intracanal instruments and 5.25% NaOCl and final irrigation with 2% chlorohexidine. To obtain canal disinfection slurry of calcium hydroxide was temporized in the canal. In subsequent appointments 3-4mm apical stop was created with mineral trioxide aggregate and allowed to set. Subsequently the root canals were obturated with thermoplasticized guttapercha. A composite resin restoration sealed the access cavity. A 3 month, 6 month and 1 year follow-up revealed clinically asymptomatic and adequately functional tooth. Results: A positive clinical resolution of this case is encouraging for the use of white MTA as a apical plug, in immature teeth with open apex. Conclusion: Apexification in one step using an apical plug of MTA can be considered a predictable treatment and may be an alternative to use a long term calcium hydroxide apexification. Keyword: Apical plug; MTA; Apexification

Thermal Insulation Monolith of Aluminum Tobermorite Nanosheets Prepared from Fly Ash

A thermal insulation monolith of aluminum tobermorite nanosheets was prepared by a facile method of one-step hydrothermal reaction and molding of a high energy ball milled slurry of fly ash, sodium bentonite, calcium hydroxide, and sodium water glass, followed by drying at ambient pressure. The monolith was characterized by XRD, FTIR, TG-DSC, SEM, TEM, BET, mercury porosimeter, and AFM. The addition of both sodium bentonite and sodium water glass plays a crucial role in preventing shrinkage and improving the porosity of the monolith. The monolith has the microstructure of randomly oriented and multually interwoven aluminum tobermorite nanosheets among which there are numerous macropores. Interestingly, the aluminum tobermorite nanosheets can be exfoliated by ultrasonication treatment to provide single-layer ultrathin nanosheets of aluminum tobermorite with a thickness of 1.18 nm and an aspect ratio of ∼1000. The monolith of aluminum tobermorite nanosheets has low apparent density (0.077 g cm–3) and very l...

Antimicrobial 2-hydroxyisocaproic acid and chlorhexidine resist inactivation by dentine.

To compare the antibacterial activity of 2-hydroxyisocaproic acid (HICA) with currently used root canal medicaments and to examine their interactions with potential inhibitors in nutrient-deficient and nutrient-rich conditions. First, the antibacterial activity of single concentrations of HICA, calcium hydroxide solution or slurry, chlorhexidine digluconate or acetate was tested against Enterococcus faecalis with and without potential inhibitors: dentine powder (DP), hydroxyapatite or bovine serum albumin, in a low concentration of peptone water. Relative viable counts were determined by culture at 1, 24 and 48 h. In the second set of experiments, the activity of three concentrations of HICA was evaluated against two isolates of E. faecalis with and without potential inhibitors in nutrient-rich thioglycollate broth using a modification of a standard microdilution method. The minimum bactericidal concentration was determined by culture at 1, 24 and 48 h. Concentrations of ≥33 mg mL(-1) of HICA were found to be bactericidal against E. faecalis in both nutrient-deficient and nutrient-rich environments at 24- to 48-h incubation, whereas the initial activity of Ca(OH)2 slurry was lost at 48-h incubation. HICA tolerated well all tested potential inhibitors up to 19 mg mL(-1) . DP concentrations higher than this inhibited its activity in a dose-dependent manner in both environments. DP demonstrated moderate antibacterial activity, and it enhanced the otherwise limited activity of Ca(OH)2 slurry and solution. DP did not impact on the activity of chlorhexidine. These results support the long-term antibacterial activity of HICA and indicate its tolerance to clinically relevant concentrations of dentine and other inhibitors commonly present in the root canal system. Therefore, HICA may have potential as an interappointment medication in the treatment of root canal infections.

Preparation of the monolith of hierarchical macro-/mesoporous calcium silicate ultrathin nanosheets with low thermal conductivity by means of ambient-pressure drying.

Calcium silicate monolith was prepared by the hydrothermal reaction of a slurry of SiO2 , calcium hydroxide, and surfactant (OP-10) obtained by high-energy ball milling, followed by drying at ambient pressure. By using this strategy, the shrinkage due to the collapse of pores during the drying of porous materials, which is a commonly observed phenomena, was successfully avoided. It has a unique microstructure of hierarchical macro-/mesoporous ultrathin calcium silicate nanosheets with a layered gyrolite crystalline structure. Very interestingly, the calcium silicate nanosheets can be peeled off to give a single-layer nanosheet (1.23 nm) of gyrolite by ultrasonication. The monolith has a low apparent density (0.073 g cm(-3) ) and low thermal conductivity (0.0399 W K(-1) m(-1) ). The reasons behind why the formation of the unique hierarchical macro-/mesoporous ultrathin nanosheets avoids shrinkage during the hydrothermal reaction and drying, and considerably decreases the thermal conductivity, is discussed.

The Effect of Carbonation Conditions on the Properties of Carbohydrate-Calcium Carbonate Hybrid Pigments

The influence of two polysaccharides, native corn starch and carboxymethyl cellulose (CMC), on the precipitation of calcium carbonate was examined by utilizing two different carbonation processes. In a batch process, carbon dioxide gas was fed through calcium hydroxide slurry at pH 11.5 to 12.0. The reaction was complete when the pH had been decreased to 7. In a fed-batch reaction, the carbon dioxide was dissolved in water while calcium hydroxide was pumped into the water, maintaining a constant pH of 6.0±0.5. Scanning electron microscopy, particle size analysis, and specific surface area analysis were used to characterize the structure of the precipitated calcium carbonate (PCC) pigments. In application testing, the impact of modified pigments on paper properties was examined. The results showed that carbohydrates can significantly affect the crystallization of calcium carbonate, but the influence depends on the precipitation conditions and the type and concentration of the carbohydrate added. The starch-modified PCC, produced by the fed-batch reaction, improved the mechanical properties of the paper, whereas CMC-modified PCC yielded paper with good surface and optical performance but weakened strength properties.

Effect of some organic solvent–water mixtures composition on precipitated calcium carbonate in carbonation process

Precipitated calcium carbonate particles were obtained during carbonation of calcium hydroxide slurry with carbon dioxide. Aqueous solutions of isopropyl alcohol, n-butanol and glycerol were used as solvents. Concentration of organic additives in the reactive mixture was from 0% to 20% (vol). Precipitation process were performed in a stirred tank reactor equipped with gas distributor. Multimodal courses of particles size distribution were determined for produced CaCO3 particles. Calcium carbonate as calcite was precipitated in all experiments. The mean Sauter diameter of CaCO3 particles decreased when the concentration of all used organic additives increased. The amount of small particle fraction in the product increased with the increasing concentration of organic solvents. Similar physical properties of used liquid phase resulted in the similar characteristics of obtained particles.

Management of open apex with mineral trioxide aggregate-2 case reports

The permanent teeth with open apex and large periapical lesion are diffi cult to treat as a traditional root canal procedure, therefore calcium hydroxide place an important role in reducing the periapical infl ammation. Management of open apex can be done using mineral trioxide aggregate (MTA) which can be placed in apical 3-4 mm. The case reports present two cases with traumatized upper anterior teeth. The radiographic evaluation revealed open apices with blunderbuss canals, the canal was cleaned using intracanal instruments and 5.25% NaOCl and fi nal irrigation with 2% chlorhexidine. To obtain canal disinfection slurry of calcium hydroxide was temporized in the canal. In subsequent appointments, 3-4 mm was created with MTA and allowed to set. Subsequently, the root canals were obturated. A positive clinical resolution of this case is encouraging for the use of white MTA as an apical plug, in immature teeth with open apex.

A temporary filling material used for coronal sealing during endodontic treatment may cause tooth fractures in large Class II cavities in vitro

To investigate the use of a zinc oxide/zinc sulphate-based cement (Coltosol(®) F, Coltène Whaledent, Cuyahoga Falls, OH, USA) as a temporary filling material during multiple-visit root canal treatments and the occurrence of cracks within the filling material or the tooth. Root canals of one hundred and twenty-two extracted human molars were prepared using ProTaper instruments up to size F2. After root canal preparation, standardized mesial-occlusal-distal cavities were prepared. The buccal-lingual/palatal width of the cavities was 4.5 mm), so that the remaining cavity walls had a mean thickness of 3.5 mm. Teeth were checked for cracks and fracture lines using a stereomicroscope with 10× magnification. A calcium hydroxide slurry was used as an intracanal dressing. The teeth were divided into three groups. In the Coltosol group, the cavity was filled with Coltosol(®) F. In the Coltosol-Clearfil group, a 2-mm layer of Coltosol(®) F was placed into the coronal pulp chamber, the remaining cavity was filled with Clearfil(™) . In the Clearfil group, a foam pellet was placed onto the orifices of the root canals, the remaining cavity was filled with Clearfil(™) . In the control group, the cavities were left without any filling material. The teeth were stored in water at 37 °C for 14 days and examined every 24 h under a stereomicroscope for fracture lines occurring on the tooth surface or in the filling material. In the Coltosol group, fractures within the filling material were observed in 28 (85%) of 33 teeth. 13 (39%) teeth had tooth fractures. Amongst these teeth, 8 (61%) had root fractures, 1 (8%) had a crown fracture and 4 (31%) had a root-crown fracture. Coltosol(®) F, when used alone as a restorative material, led to tooth fractures in Class II cavities in teeth undergoing root canal treatment. Tooth fractures may occur 4 days after placement of the filling.

Tracking the formation of vaterite particles containing aminopropyl-functionalized silsesquioxane and their structure for bone regenerative medicine.

Vaterite particles containing aminopropyl-functionalized silsesquioxane (SiV) were prepared as osteogenic devices for bone regeneration. The SixV particles (x = 0, 2.6 and 4.9 wt%) were synthesized by reacting a slurry of calcium hydroxide with carbon dioxide gas in the presence of γ-aminopropyltriethoxysilane (APTES), a source of soluble silica which would genetically enhance osteogenesis. The obtained Si2.6V and Si4.9V particles were monodispersed with a diameter of 1.4 and 1.5 μm, respectively. The Si2.6V particles showed spherical morphologies. On the surface of the Si4.9V particle small particles were aggregated, resulting in the formation of irregular textures. Transmission electron microscopy of a sectioned Si2.6V particle revealed that the vaterite particles were present as lamellae with a length of 5-20 nm and surrounded by silsesquioxane from APTES. Moreover, the vaterite lamellae were relatively orientated to the c face of the unit lattice, where it is known to be highly polarized, compared to pure vaterite, due to the exposure of the uni-ionic plane with positive (Ca2+) or negative (CO3 2-) charge. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) revealed the co-existence of amorphous calcium carbonate (ACC) in the SiV particles. On contact with physiological pH buffer solution, the vaterite was transiently stabilized and subsequently dissolved and released after the dissolution of silsesquioxane from the particles. This stabilization time was significantly increased with the increase in silicon content. The vaterite was observed in Si2.6V particles up to 3 h of soaking, which extended up to 12 h in Si4.9V particles. The formation of the particles from the precursor gel was monitored by laser Raman spectroscopy and ATR-FTIR. During the initial 1 to 2 h of the aging step, maturation of ACC into vaterite and condensation of monomeric APTES molecules were found to begin simultaneously. These reactions proceeded up to 7 h of the analysis period. The condensation of hydrolyzed APTES is suggested to occur in the vicinity of growing vaterite, which might play a role in the enclosure of vaterite in silsesquioxanes.

A study on bioethanol production from cashew apple pulp and coffee pulp waste

Abstract Bioethanol production from dry cashew apple pulp and coffee pulp was investigated. The pulp was digested with 2% sulfuric acid and subjected to high pressure (15 psi) cooking at 120 °C for 10 min followed by further 1 and a half hour pressure cooking at 90 °C to solubilize the pulp. Solubilized pulp was filtered and the debris on the filter paper was washed with minimum quantity of distilled water and then oven dried to find the weight of the insoluble lignin mass. Total sugar content in squeezed and dried cashew apple pulp (CAP), dry coffee pulp (DCP) and wet coffee pulp (WCP) was found to be 2.12, 1.62 and 0.62 g/100 ml of hydrolyzate. Reducing sugar content in squeezed CAP, DCP and WCP was found to be 0.14, 0.71and 0.23g/100 ml of hydrolyzate. Filtrate was neutralized with thick suspension of calcium hydroxide slurry until the pH reaches to 6.0. Neutralized slurry was kept at lab temperature overnight and the supernatant was decanted through filter paper. To 150 ml of filtrate yeast ( Saccharomyces creviciae ) was added at a concentration of 5.0 g/l concentration and subjected to fermentation for 48 h at 30 °C in a shaker incubator at 120 rpm. Ethanol content in the fermented broth was estimated by titrimetric and gas chromatographic method. Ethanol yield in the fermented broth was found to be 0.5, 0.46 and 0.46 g/g of sugar in squeezed CAP, DCP and WCP. Theoretical ethanol yield ( Y max %) of squeezed CAP, DCP and WCP was found to be 46, 9.35 and 40% respectively.