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Aim: The aim of this non-inferiority randomized clinical trial was to compare the efficacy of an iodoform-based paste (Guedes-Pinto –(GP)) as a filling material in pulpectomies of primary teeth, and a standard material composed by calcium hydroxide and iodoform (CaOH/Iodof paste; Vitapex®). Design: A total of 104 teeth from 61 children (3–8 years old) were randomly allocated to two groups according to filling materials. Children were followed up for 24 months. The primary endpoint was the treatment success rate evaluated through clinical and radiographic examinations at follow-up, and the secondary outcome was the analysis of the canal filling quality. Differences in the proportion of treatment success was calculated based on 95% confidence intervals (95% CI) and with the Miettinen and Nurminen method in the intention-to-treat population, considering a −20% of the non-inferiority limit. Results: From 104 randomized teeth, 102 were followed up after 24 months (attrition rate of 1.9%). The success rate of teeth treated with the GP paste was 86.8% (95% CI: 69.9–94.9) and 78.4% (95% CI: 61.8–89.1) with the CaOH/Iodof paste. Consequently, a non-inferiority of the GP paste was observed when compared to the CaOH/Iodof paste (P

At present, the cyanide gold extraction process is still the main technology for gold production. Generated cyanide tailings containing highly toxic substances exhibit potential environmental risks. These tailings are in urgent need of purification treatment, especially after being classified as hazardous waste. In this study, the impacts of elution methods, operating time, tailings/water ratios, reagent types on the elution rates of cyanide were investigated. Furthermore, the composite elution method developed in this research was extended for engineering. Results showed that the optimum elution conditions were determined to be: stirring elution, tailings/water ratio (M/V; 1:1) and operating time (10-20 min). Besides, 4 reagents (sodium dodecyl benzene sulfonate, cyclodextrin, sodium silicate and calcium hydroxide) were selected from four categories of 21 reagents for further composite elution. The cyanide elution rate was the highest (90.7%±0.1%) while the molar ratio of these 4 reagents was 5:2:2:1. Moreover, the combination of reagent elution and positive pressure filtration improved the elution efficiency of cyanide (92.6%±0.8%). And the cyanide content in the toxic leaching solution was lower than the standard value (5.0 mg/L). Furthermore, the composite elution method developed in this study was also extended for engineering. The concentration of cyanide in the leachate was5.0 mg/L, and was stable during 189 days of detection. Notably, the effluent can be reused directly, or reused after further treatment. The zero discharge of effluents and solid wastes was realized in the processes. The above results provided supports for the engineering treatment of cyanide tailings.

Frescoes were developed as religious paintings in medieval Europe before the rise of oil paintings. When coloring with natural pigments on a slaked lime plaster, calcium carbonate gradually forms a coating on the pigments at the surface of the plaster over a period of decades to a hundred years. Many frescoes have been maintained for hundreds of years and have become part of historic heritage. However, the making of frescoes is rarely selected as a general art painting method because it takes a lot of time for complete carbonation to occur. This study demonstrated that a geomimetic ceramic hardening technique using calcium hydroxide and calcium carbonate, followed by subsequent acceleration of carbonation at the surface of the calcium hydroxide with supercritical carbon dioxide, could assist in forming frescoes in a short time. The immobilization of the pigment used on the base calcium hydroxide body was evaluated by a scratch test with emery paper, and pigment color differences were measured by a colorimeter. Furthermore, the micromorphology of the resultant frescoes fabricated by the geomimetic technique in a short time was investigated to evaluate the progress of carbonation. As a result, frescoes could be fabricated in a short time by combining a geomimetic technique and carbonation with supercritical carbon dioxide using a novel pigment that is a mixture of pigment and calcium hydroxide. The pigment in the final sample was completely fixed to the base calcium hydroxide body, and the pigment color was brighter than the original pigment color due to the densification of calcium carbonate after supercritical carbon dioxide treatment.

Metastable vaterite blocks are expected to show high reactivity. However, they have not been reported to date. In this study, the feasibility of fabricating an artificial vaterite block was investigated by exposing a Ca(OH)2 compact to CO2 under several conditions. Under a 100% H2O atmosphere, a calcite block was formed within three days. Under a 100% methanol atmosphere, no carbonation was observed for seven days. Under 90% methanol without atmospheric flow, a vaterite block containing 5 mass% of unreacted Ca(OH)2 and 3 mass% of calcite was formed after 24 h. On day 7, it was transformed into a block with 70 mass% of calcite, 27 mass% of vaterite, and 3 mass% of unreacted Ca(OH)2. By contrast, under 90% methanol with atmospheric flow to remove the accumulated H2O in the compact, a pure CaCO3 block of 98 mass% vaterite and 2 mass% calcite was formed on day 3. Therefore, the regulation of the amount of H2O is important for fabricating vaterite blocks. Porosimetry measurements revealed that the calcite block fabricated under 90% methanol without atmospheric flow demonstrated a pore size profile closer to that of the vaterite block than that of the calcite block fabricated under 100% H2O atmosphere because the vaterite with small spherical crystals was formed initially before its transformation to calcite.

To efficiently remove high concentrations of hexavalent chromium (Cr(VI)), calcium–aluminum-layered double hydroxide (CaAl-LDH, denoted as CAL), and polypyrrole-modified CAL (CAL-PPy) were prepared by hydrothermal and in situ polymerization methods, respectively. The chemical structure, morphology, and elemental results indicated that the chain-like polypyrrole was decorated with hexagonal CAL. The specific surface area of CAL-PPy increased from 8.746 m2/g to 24.24 m2/g. The adsorption performances of CAL and CAL-PPy for aqueous Cr(VI) were investigated using batch equilibrium experiments. The decontamination process of aqueous Cr(VI) (100 mg/L) reached the equilibrium state within 50 min, and the kinetic data met the pseudo-second-order kinetic equation. The Langmuir model described the isothermal data properly, and the obtained theoretical adsorption capacity of CAL for Cr(VI) at 318 K was 34.06 mg/g, while that of CAL-PPy was 66.14 mg/g. The removal mechanisms involved electrostatic attraction, surface complexation, anion exchange, and reduction to low-toxicity Cr(III). Therefore, CAL and CAL-PPy have underlying applications in treating real wastewater containing Cr(VI).

This study aimed to evaluate the pulpal responses of monkey's pulp after direct pulp capping (DPC) with the novel mineral trioxide aggregate containing phosphorylated pullulan-based material (MTAPPL). Seventy-two teeth were randomly divided into four groups: MTAPPL; Nex-Cem MTA (NX); TheraCal LC (TH); and Dycal (DY). Histopathological changes in the pulps were observed at days 3, 7 and 70. On day 3, mild inflammatory responses were observed in the MTAPPL, no to moderate inflammatory responses in the TH, whereas moderate inflammatory responses in the NX and DY. No mineralized tissue formation (MTF) was observed in all groups. On day 7, no or mild inflammatory responses were observed in all groups. Initial MTF was observed except for DY. No inflammation with complete MTF including presence of odontoblast-like cells was observed in the MTAPPL, NX and TH groups at day 70. These findings indicate that MTAPPL could be an efficient DPC material.

Hypothesis The mechanism of calcium silicate hydrate (CSH) formation, a relevant component of cement, the largest used material by mankind, is well documented. However, the effects of nano-sized materials on the CSH formation have not yet been evaluated. To this aim, a kinetic study on CSH formation via the “pozzolanic reaction” of nanosilica and calcium hydroxide nanoparticles, and in the presence of hydroxypropyl cellulose (HPC) as hydration regulator, is reported in this paper. Experiments The reagents were mixed with water and cured at 10, 20, 30 and 40 °C. The reaction kinetics was studied with differential scanning calorimetry (DSC). A Boundary Nucleation and Growth model (BNGM) combined with a diffusion-limited model was used to analyze the data, yielding induction times, reaction rates, activation energies, nucleation and linear growth rates, and the related diffusion coefficients. Findings The rate constants kB and kG, which are, respectively, the rate at which the nucleated boundary area transforms, and the rate at which the non-nucleated grains between the boundaries transform, increase with temperature. Their different temperature dependence accounts for the prevailing effect of nucleation over nuclei growth at progressively lower temperatures. The nucleation rate, IB, is strongly enhanced when using nanomaterials, while the linear growth rate, G, is limited by the tightly packed structure of the transforming matrix. HPC influences the kinetics between 10 and 30 °C; at 40 °C the temperature effect becomes predominant. HPC delays induction and acceleration periods, increases Ea(kB), and enhances the reaction efficiency during the diffusion regime, by retaining and delivering water over the matrix, thus allowing a higher water consumption in the hydration reaction of CSH.

The evaluation of nano-priming effect with galactomannan stabilized Phyto-complexed calcium hydroxide (Ca(OH)2), selenium oxyanion‑calcium hydroxide SeO-(Ca(OH)2), and selenium‑calcium hydroxide Se-(Ca(OH)2) nanocomposites was carried out in Vigna radiata (Green gram) seeds. The green source Cassia angustifolia seed rich in galactomannan and other phytoconstituents was detected experimentally and characterized with GC–MS, UV, FT-IR, NMR, XRD, and SEM studies. The highly active galactomannan and other biomolecules, enable their terminal oxygen and hydroxide groups to bind with calcium and selenium ions through bidentate and monodentate chelation, followed by bio-reduction. On the mild-thermal agitation, bio-stabilized (Ca(OH)2), SeO-(Ca(OH)2), and Se-(Ca(OH)2) nanocomposite coated with seed-derived biomolecules were precipitated under an alkaline condition. The size and morphological parameters of bio-fabricated nanocomposites were characterized to exhibit the spherical and hexagonal shape in nanoscale images of size 17.9 nm for (Ca(OH)2), 56.2 nm for SeO-(Ca(OH)2), and 69.3 nm Se-(Ca(OH)2). The sub-standard seed lot of Vigna radiata (Green gram) seeds (71%) was examined using synthesized nanocomposites at various concentrations, and the obtained physiological parameters in seedlings were compared with hydro-primed seeds. The nano-priming action of all the Phyto-complexed nanocomposites was predicted with a positive response, where the porous Se-(Ca(OH)2) possess high efficacy interaction on seed embryos and beneficially results at 90% germination.

The rapid growth of population with increased facilities for comfort nowadays leads to a drastic depletion of natural resources. The present work emphasizes the re-refining process of waste lubricating oil by the solvent-extraction flocculation process. Re-refining is considered by many as a preferred option in conserving resources, minimizing waste, and reducing environmental hazards to a great extent. The effect of various parameters like refining time, refining temperature, solvent to waste oil ratio, flocculant dosage, adsorbent to distilled oil ratio has been elaborately studied, and the optimum yield percent was obtained at 33 °C of refining temperature, 20 min of refining time with a solvent to waste oil ratio of 5:1 (w/w). Various solvents like iso-butanol and n-butanol were used, and iso-butanol was found to produce a higher yield of 72%, which is 2% higher than the solvent n-butanol. Calcium hydroxide was used as a flocculant, and a concentration of 2 kg of flocculant per kg of solvent was optimum. The flashpoint, ash content, and viscosity index of re-refined oil were 210 °C, 0.25 g, and 175, respectively, comparable to virgin lube oil. The purity and the existence of oxidation products were elaborately analyzed by FTIR and GC–MS analysis. Thus, the refined oil obtained can effectively mitigate the ever-growing oil crisis and help create a healthy and pollution-free environment.

Aim To evaluate the antibacterial efficacy of calcium hydroxide (CH) with antibiotic combinations: daptomycin and gentamicin against Enterococcus faecalis (E. faecalis) dentinal biofilm. Materials and methods Sixty freshly extracted single-rooted mandibular premolars were inoculated with E. faecalis(ATCC 29212) (n = 30) (group A) and clinical isolates (n = 30) (group B) for 3 weeks to form a biofilm. The tooth samples of groups A and B were randomly divided into three subgroups of 10 each, groups 1A and 1B (CH), groups 2A and 2B (CH+G), groups 3A and 3B (CH+D), depending on the medicaments to be placed for one week. The difference between initial and final CFU was calculated and statistically analyzed. Results Among the clinical isolates, CH-antibiotic combinations were more effective than CH alone, which was statistically significant (p = 0.006). Conclusion The dentinal biofilm of clinical isolates of E. faecalis strains exhibited more reduction in bacterial colonies with CH in combination with antibiotics (D and G). Clinical significance Daptomycin and gentamicin when used as an intra-canal medicament in combination with CH are effective in eliminating E. faecalis. Keywords: Calcium hydroxide, Daptomycin, Dentinal biofilm, E. faecalis, Gentamicin.

Recently, the capture of carbon dioxide (CO2) using alkaline waste and byproducts has garnered considerable interest. Construction sludge may be categorized as alkaline waste, as it often exhibits high alkalinity during its generation or intermediate treatment. Hence, researchers have attempted to accelerate pH neutralization and recycle alkaline construction sludge by curing it under a high CO2 concentration. By exposing concentrated CO2 gas to an alkaline sludge, cement hydrates such as calcium hydroxide and calcium–silicate–hydrate gels form calcium carbonate (CaCO3). Subsequently, the generation of CaCO3 is expected to reduce the pH of the sludge. However, the amount of CO2 captured in sludge has not been investigated extensively, unlike those of other alkaline wastes. Therefore, the amount of CO2 captured in alkaline sludge that is associated with pH neutralization is evaluated in this study. It is demonstrated that accelerated carbonation tests using a CO2 incubator and carbonate content evaluation tests based on the gas pressure method successfully reveal the amount of CO2 captured in the alkaline sludge that is associated with pH neutralization. Additionally, the test results show that the amount of mCO2 (i.e., the amount of CO2 captured per 1 g of dry mass of alkaline sludge) increases with ΔpH (ΔpH is the difference between the initial pH and the pH after the alkaline sludge is neutralized). A maximum of 0.021 g of CO2 is captured per 1 g of dry mass of alkaline sludge when the addition ratio of quicklime AQL = 3% and 0.040 g when AQL = 6%. The CO2 capture ratio mCO2/mCO2max, which represents the ratio of CO2 captured in the sludge to the maximum capturing capacity, increases with ΔpH. CO2 capture ratios of up to 90.0% and 84.9% are recorded when AQL = 3% and AQL = 6%, respectively. It is discovered that a higher AQL results in a higher mCO2. Moreover, the test results indicate that a higher AQL causes a more significant change in the CO2 capture ratio, even when the pH decreases slightly.

Calcium hydroxide nanoparticles dispersed in ethanol or 2-propanol have been proposed for deacidification treatments of cellulose-based supports and are currently adopted by many paper and painting...

The development of inexpensive and environmentally friendly graphene-like carbon is critical for its integration into industrial products. This work highlights the production of graphene-like carbon structures from calcium hydroxide. The chemical vapor deposition conditions to grow graphitic carbon on a calcium hydroxide catalyst are reported. Acetylene, steam, and calcium hydroxide are used to grow a crumpled carbon morphology. The crumpled carbon resulted in a high surface area of 1276 m2/g and high electrical conductivity (>105 S/m). Additionally, the significance and origin of the C 1s X-ray photoelectron spectroscopy (XPS) π–π* plasmon loss peak as it is related to high electrical conductivity is reported. A unique mechanism for the catalytic process involving calcium acetylide is proposed. Several deposition times, steam concentration, and catalyst morphology were tested to synthesize a variety of carbon morphologies from calcium-based materials. Crumpled carbon, hollow nanospheres, bamboo-like carbon nanotubes, multi-walled carbon nanotubes, and graphene fiber morphologies were all formed using calcium-based catalysts. Multiple reaction conditions, a scaled reaction (300 g), and catalyst recyclability were investigated. Calcium-based materials were then used as catalysts for the growth of other graphene-like carbons.

The accelerated chemical-industry has caused a rapid increase of calcium-containing alkali wastes, containing a large amount of calcium, magnesium, aluminum, and iron ions and caused a great risk to environment. Anaerobic digestion or dark fermentation is one of the most promising technologies to recover biogas, such as methane and hydrogen. Nevertheless, the hydrolysis processes of lignocellulosic biomass and waste activated sludge were the rate-limiting step of the biochemical reactions, which focused on pretreatment to improve the biodegradability of substrate. In addition, when some easily acidified wastes, such as kitchen residue, fruit and vegetable waste, and high concentration organic wastewater, are used as substrate to produce hydrogen and methane, volatile fatty acid accumulation often occurs, causing the process instability. Thus, this paper reviewed the main roles of calcium-based alkali materials such as calcium oxide, calcium peroxide and calcium hydroxide on the substrate pretreatment for obtaining high biodegradability, while others (e.g. calcium carbonate, lime and red muds) used as additives for maintaining process stability, thereby increasing biogas yield from anaerobic digestion and dark fermentation.

Background: Calcium hydroxide is the gold standard medicament for root canal treatment. Enterococcus faecalis, the primary cause of intraradicular persistent endodontic infection, is often identified even after endodontic treatment. Thymoquinone, an active ingredient of Nigella sativa, has an antimicrobial effect on both gram-negative and positive bacteria, including E. faecalis. Purpose: This study aimed to evaluate the inhibitory effect of calcium hydroxide combined with Nigella sativa extract and determine the best ratio for the combined material. Methods: This is an experimental study comprised of six groups (n = 4 per group) based on the material and its ratio, namely; (1) calcium hydroxide; (2) Nigella sativa extract; and groups of the combination of calcium hydroxide and Nigella sativa extract with a ratio (3) 70:30, (4) 50:50, (5) 30:70, (6) 10:90. The inhibitory effect against E. faecalis was evaluated by the agar well diffusion method in Muller–Hinton agar. Observation of the inhibitory zone was performed on the first, third, and seventh days. The collected data were analysed by a one-way ANOVA and LSD post hoc test. Results: Calcium hydroxide has the highest inhibitory effect, and the combination of Nigella sativa extract with calcium hydroxide ratio 50:50 was second. The inhibitory zone of these two groups was significantly higher than in any other group (p

Aims: This study aims to compare the efficacy in alleviating pain between intracanal medicaments, namely Nitrofurantoin and Calcium Hydroxide Paste. Study Design: Randomized Controlled Trial. Place and Duration of Study: Sample: Department of Operative Dentistry, Sir Syed College of Medical Sciences, Pakistan, between January 2021 and May 2021. Methodology: 60 patients were randomly divided into 3 groups, each group having 20 patients as following: Group 1: Nitrofurantoin, Group 2: Calcium Hydroxide and Group 3: Control. Preoperative pain was recorded using a numerical pain scale. After access preparation, chemomechanical preparation was performed with subsequent placement of intracanal medicaments. Pre-operative pain score was initially recorded, followed by post-operative pain at 12, 24, 48, and 72 hours, respectively. Root canal treatment was performed in single rooted teeth with patients suffering from symptomatic irreversible pulpitis Results: Majority of the patients in all 3 groups were initially presented with moderate to severe pre-operative pain. After 72 hours post-operatively, 50% patients in Group 1 reported no pain, while 5% patients in both Group 2 and 3 had no pain. Pain significantly subsided in Group 1 as compared to Group 2 and 3. Regarding age and gender, both had no significant relationship with the pain scores in all of the 3 groups Conclusion: Nitrofurantoin has been proven to be an effective intracanal medicament in alleviating immediate post-operative pain in patients with symptomatic irreversible pulpitis as compared to calcium hydroxide. While the control group with no intracanal medicament showed little reduction in pain scores. So, nitrofurantoin can be used as a substitute to currently available standard intracanal medicaments.

Objective:To compare the clinical effects of Antibiotic amoxicillin-clavulanate and calcium hydroxide on inter appointmentpain in cases of Symptomatic Apical Periodontitis. Methodology:It was a single blind randomized controlled trial study performed in operative Dentistry Department ofLiaquat University of Medical and Health Sciences Jamshoro. This study was conducted from 02-Jan-2017 to 27-June-2017. Total n=324 patients with symptomatic apical periodontitis were targeted. Patients were randomly allocated into twogroups. Total n=162 patients in group1 treated with Antibiotic amoxicillin-clavulanate and n=162 patients in group 2 ofcalcium hydroxide. Procedure was performed by single operator. Clinical effect was assessed if pain present or absent after24 hours and 7 days on recalled visit and was labeled as positive when there was no pain (0-3 on VAS) and as negativewhen there was pain (4-10 on VAS). Data of the study was analyzed by using the SPSS version 20. Mean and standarddeviation was calculated for quantitative variables like age and pre and postoperative pain. Frequency and percentageswere calculated for type of tooth. Both groups were compared byusing Chi- square test for clinical effect. Results:The average age of the patients was 39.807.36 years. There were 50% male and 50% female. Clinical effectivenesswas significantly high in group 1 than group 2 [79.01% vs. 65.43% p=0.006]. Conclusion:The findings of this study are encouraging that patients in which Amoxicillin-clavulanate was used as intracanalmedicament appeared to show a greater decrease in pain levels over the observation period when compared to the control group

Fly ash has been highly advocated to be re-utilized as a construction material. The most common utilization is to partially replace cement in a low-percentage scheme. However, there are several other schemes available to potentially use fly ash as binder in concrete that have not been widely exercised, especially those utilizing it in high to very high volume. In those schemes, high-volume fly ash (HVFA) concrete might use more than 50% fly ash to replace cement. To exploit its self-cementing properties, with or without the addition of other compounds, such as calcium hydroxide, fly ash might be used in very high percentage of cement replacement. In geopolymeric system, fly ash acts as the precursor of a stable binder, with the presence of highly alkaline solution. This paper demonstrates a model to investigate the potential of fly ash in several binder systems. The results show that fly ash from a good source can be utilized as an alternative binder in several different schemes.

Introduction: The purpose of current research is to assess the in vitro antimicrobial efficacy of different medicaments with two different vehicles against Candida albicans (C. albicans). Materials and Methodology: An agar well diffusion assay was used to determine the experimental medicaments' efficacy against C. albicans. Medicaments were divided into six groups, which includes Triple antibiotic powder (TAP) with saline or chitosan, Double antibiotic powder with fungicide (DAPF) with saline or Chitosan, and calcium hydroxide with saline or Chitosan. The diameters of growth inhibition zones were recorded and compared for each group for three days, i.e., 1,4,7 days. The differences between groups were analyzed by Kruskal-Wallis and Mann-Whitney U tests. Results: The largest inhibition zones were observed for the double antibiotic paste + fungicide with chitosan and the smallest for Ca(OH)2 with saline. Over a week, zones of inhibition were consistent only with group V – double antibiotic paste with fungicide and chitosan as the vehicle. Conclusion: DAPF with chitosan is more efficient against Candida albicans. Since the endodontic infections are polymicrobial in origin, the combined local drug delivery of antimicrobial agents such as ciprofloxacin, metronidazole, doxycycline along with antifungal drugs such as fluconazole with an efficient drug carrier (chitosan) is recommended to combat the microbial load.

Aims: To compare the antimicrobial efficacy of Bioactive glass, combination of 1% Chlorhexidine gluconate gel and Calcium hydroxide powder and 1% Chlorhexidine gluconate gel as intracanal medicament in primary molars.Settings and Design: In vivo study design Methods and Material: The present study was conducted in the Department of Pediatric and Preventive Dentistry, Krishnadevaraya College of Dental Sciences and Hospital, Bengaluru. This study included 48 subjects within the age group ranging from 4-11 years who were indicated for multi visit Pulpectomy. These subjects were randomly divided into three experimental groups, containing sixteen samples per group. Group 1: Bioactive glass; Group 2:1% Chlorhexidine gel and Calcium hydroxide powder; Group 3:1% Chlorhexidine gel. Under rubber dam isolation, following lesion sterilization S0 sample was obtained. Following access opening and working length, sample S1 was obtained and the respective medicament was placed inside the canals after cleaning and shaping and a double seal was done with ZOE and GIC. Patient was recalled after a period of 5 to 7 days and the medicaments were flushed under isolation and sample S2 was obtained. Pulpectomy procedure was then completed. S0, S1, S2 samples were subjected to microbiological analysis and the total bacterial count in CFU/ml was calculated.Statistical analysis used: Kruskal Wallis Test and One-way ANOVA.Results: The mean percentage of reduction of bacterial count from S1- S2 (Before and after placement of medicament) with Group 1: Bioactive glass was 75.7%, with Group 2:1% Chlorhexidine gluconate and calcium hydroxide was 52% and Group 3:1% Chlorhexidine gluconate was 28.6%, revealing that bioactive glass has the superior antibacterial efficacy when compared with other groups. Antibacterial efficacy of bioactive glass was significant in both primary maxillary and mandibular first molar and second molar proving it to work best for all types of root anatomy in mixed dentition population. Superior clinical and microbiological results were found when bioactive glass was used as intracanal medicament in both intraoral and extra oral abscess cases in primary molars.Conclusions: Bioactive glass; intracanal medicament; primary dentition; primary molar; mixed dentition.

Introduction More data are needed before affirming that single-visit approaches are effective and safe for regenerative endodontic procedures (REPs). This study compared clinical and radiographic outcomes of REPs between interappointment dressing or single-visit protocols. Methods Twenty young patients presenting traumatized immature teeth with pulp necrosis were divided into 2 groups. Teeth were submitted to 6% sodium hypochlorite and 2% chlorhexidine irrigation and to 17% EDTA use before blood clot induction. In the interappointment dressing group (n = 11), calcium hydroxide was used with 2% chlorhexidine gel for 21 days before scaffold induction. In the single-visit group (n = 9), the scaffold was induced during the only appointment. Patients were followed up for 24 months. Primary, secondary, and tertiary outcomes were assessed by 3 independent evaluators. Preoperative and follow-up radiographs were assessed for quantitative measurements of the apical diameter, root width, root length, and cervical barrier placement and compared between groups using the t test or Mann-Whitney U test. Categoric variables were assessed with the G test and the Fisher exact test and continuous variables with the Mann-Whitney U test. Statistical significance was set at 5%. Results One tooth showed persistence of infection. No difference was observed in cervical barrier placement (P > .05); between groups regarding primary, secondary, and tertiary outcomes (P > .05); and in parameters of quantitative radiographic outcomes (P > .05). Conclusions Completing REPs with an interappointment dressing or a single-visit protocol presented similar clinical and radiographic outcomes. A single-visit protocol of REPs using 6% sodium hypochlorite, 2% chlorhexidine, and 17% EDTA permitted satisfactory outcomes in necrotic immature permanent teeth.

In papermaking, pre-flocculation of fillers such as ground calcium carbonate (GCC) improves the tensile strength of paper sheets. However, the pre-flocculated fillers mostly suffer from the instability of the floc shape such as the decrease in floc diameter with time elapse after preparation and no improvement of bulk and stiffness. The addition of calcium compounds such as calcium oxide or calcium hydroxide to the pre-flocculated GCC, and injection with carbon dioxide caused pre-flocculated GCC flocs to be covered with newly formed calcium carbonate. This product, called post hybrid calcium carbonate (pHCC), was found to be more stable in size and gave better sheet strength than the pre-flocculated ones. Furthermore, pHCC gave remarkably higher bulk and stiffness than the pre-flocculated flocs did without impairing smoothness that was essential in printing paper. The proper use of pHCC in papermaking could allow the production of high loaded paper with more than 10% higher filler contents, which could reduce paper production cost and save drying energy. The proportion of the newly formed calcium carbonate in pHCC, turbulence intensity at preparation stage, and the effect of storage time were investigated.

Although epigallocatechin-3-gallate (EGCG) from green tea has been successfully used in the prevention and treatment of several infectious and immunoinflammatory diseases because of its proven anti-inflammatory, antioxidant, antimicrobial, and antiresorptive role, its use as an intracanal dressing has not been proposed. The aim of this study was to develop a formulation based on EGCG for endodontic use by assessing its physicochemical and biological properties.Initially, physicochemical characterization of EGCG was performed by ultraviolet-visible and fluorescence spectroscopy to evaluate if the properties were maintained in acidic pH and time (1-6, 24, and 27 hours). After that, biological studies evaluated the developed formulation of EGCG at different concentrations (1.25, 5, 10, and 20 mg/mL). The tissue compatibility with subcutaneous tissue of mice was evaluated by plasma leakage after 24 hours and the examination of macroscopic and microscopic features at 7, 21, and 63 days after the insertion of polyethylene tubes containing the formulations. The repair of experimentally induced periapical lesions in dog's teeth by radiographic and histopathologic analysis was also evaluated. The scores were statistically analyzed by the chi-square and Fisher exact test. Analysis of variance followed by the Tukey posttest were used for the quantitative analysis. The significance level was 5%.The physicochemical characterization performed under ultraviolet-visible spectrophotometry showed that the EGCG properties remained unaltered in acid pH and function of time, keeping its wavelength to 274 nm. Macroscopic parameters evaluated at 7, 21, and 63 days showed that all concentrations presented no epithelial ulceration or presence of mild superficial tissue necrosis, edema, or vascularization with no significant difference in the control group. During all periods of microscopic examination, all groups presented the absence of abscess foci and edema and the presence of fibrous capsule and neovascularization. The presence of reparative tissue with a gentle presence of neutrophilic inflammatory cells was also observed for all groups, except for the calcium hydroxide paste group, which presented a more pronounced inflammation and tissue necrosis at days 7 and 21 (P .001). At day 63, all groups presented an absence of inflammatory infiltrate and necrosis. The evaluation of dog teeth showed that treatment with the EGCG formulation provided a reduction of the periapical radiolucent area and allowed the repair of apical and periapical tissues (P .05).The developed formulation based on EGCG from green tea presented physicochemical stability and tissue compatibility and provided the repair of periapical lesions when used as an intracanal dressing.

This study evaluated the effect of different protocols for Ca(OH)2 removal on the bond strength (BS) of epoxy resin-based sealer in long oval root canals. Forty-eight mandibular incisors with long oval root canals were selected by CBCT. Biomechanical preparation was performed, the samples were filled with Ca(OH)2 paste and distributed in four groups (n = 12): G-without Ca(OH)2 paste (C); G2-syringe/needle (SN); G3-SN + XP-Endo® Finisher (XPF); G4-SN + passive ultrasonic irrigation (PUI). After 7 days, Ca(OH)2 was removed and teeth were filled using AHPlus and guttapercha. In four samples from each group, the sealer was manipulated with 0.1% rhodamine to assess sealer penetration by fluorescent laser confocal microscopy (FLCM). Samples were sectioned in slices for BS, scanning electron microscopy, and FLCM analysis. The BS data were analyzed by ANOVA and Tukey tests (α = 0.05). The lowest BS values were found for the SN group (12.89 ± 4.36) compared to C (35.55 ± 10.05), while PUI group presented intermediate values (28.57 ± 9.35) and the XPF group (31.34 ± 9.8) showed values that were sometimes similar to C group and sometimes similar to PUI group (p > .05). The analysis of the adhesive interface showed evident gaps, with the presence of residues between the dentin and the filling material for the SN group, and for C, XPF and PUI groups juxtaposed adhesive interface. FLCM images showed sealer penetration in the dentinal tubules along the entire perimeter for C, XPF, and PUI groups. Ca(OH)2 removal with XPF and PUI from long oval root canals resulted in higher bond strength values compared to SN, besides better sealer penetration on dentinal tubules and juxtaposed adhesive interface.

The goal of endodontic treatment is to prevent and control of pulp and periradicular infections. Calcium hydroxide has a beneficial biological property as an intracanal medicament and can be combined with cresotin to disinfect bacteria in root canals, especially Enterococcus faecalis (E. faecalis) which is the most frequently isolated strain in the root canals. The aim of this study was to investigate in vitro the antimicrobial activity of calcium hydroxide, cresotin, and combination calcium hydroxide and cresotin (Ca[OH]2+Cresotin, 1:1 and 1:2) against E. faecalis. Antibacterial activity was determined by the agar diffusion method. The test medicaments were placed inside the hole that made in the inoculated agar medium. The zone of growth inhibition was measured and recorded after incubation for each plate, and the result was analysed statistically with ANOVA. The in vitro antimicrobial effects of combination calcium hydroxide and cresotin (Ca[OH]2+Cresotin, 1:2) has more prominent antimicrobial activity than others, and calcium hydroxide is more effective than cresotin alone. The antimicrobial activity of combined calcium hydroxide and cresotin is more effective in killing E. faecalis in comparison to the other treatments.

BACKGROUND Given that periapical bacterial infections are considered as one of the causes of endodontic treatment failure, and biomechanical methods may not be able to eliminate bacteria resistant to endodontic treatment, including Enterococcus faecalis; therefore, this study was conducted to compare the antibacterial effects of Golpar and Kakoti extracts with calcium hydroxide and chlorhexidine against E. faecalis. METHODS At first, Heracleum persicum (Golpar) and Ziziphora tenuior L. (Kakoti) plants were extracted by ethanol solvent using the cold maceration method and a vacuum distillation apparatus. E. faecalis ATCC 29212 was used as the standard strain in all stages of the experiment. Antibiogram, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) tests were performed to evaluate the antibacterial activity of the prepared extracts. The anti-biofilm activity of the extracts was evaluated similar to MIC evaluation but with a longer incubation time and analyzed by ELISA at a wavelength of 492 nm. RESULTS The antibiogram test showed a growth inhibition zone diameter of 4 mm only for chlorhexidine. In addition, chlorhexidine exhibited the highest inhibitory and bactericidal activities in the MIC and MBC tests, respectively (MIC / MBC < 1.562 mg / mL). The MIC of Golpar, Kakoti, and Golpar + Kakoti extracts was determined to be 50 mg / mL. No significant inhibitory activity was observed for calcium hydroxide either alone or in combination with the plants' extracts. The MBC of Kakoti extract was 50 mg / mL, and the other compounds had an MBC greater than 100 mg / mL. CONCLUSIONS The present in vitro study showed that the highest inhibitory activity against E. faecalis was related to chlorhexidine; however, Golpar and Kakoti extracts at a concentration of 50 mg / mL exhibited a proper inhibitory activity compared to calcium hydroxide. Therefore, further studies are recommended to be conducted in the future. KEYWORDS Enterococcus faecalis, Ziziphora tenuior L., Heracleum persicum, Chlorhexidine, Calcium Hydroxide, Antibacterial effects.

Aim: To investigate the effect of sodium ascorbate (SA), an antioxidant and calcium hydroxide (Ca(OH)2), a buffering agent mixture, on the shear bond strength of a luting resin to dentin, and pH changes of the extraradicular medium solution after intracoronal bleaching with hydrogen peroxide. Materials and Methods: In this in vitro study, 60 human maxillary central incisors were randomly assigned into six groups ( n: 10): Group 1: restored, no bleach; group 2: bleached, bonded immediately; group 3: bleached, treated with 10% SA applications before bonding; group 4: bleached, treated with calcium hydroxide applications before bonding; group 5: bleached, treated with CaOH2 and SA mixture applications before bonding; group 6: delay bonding by seven days. For bleach treatment in groups 2 to 6, intracoronal bleaching was performed with 35% hydrogen peroxide for four days. SA or CaOH2 or mixture of SA and CaOH2 were left in the access cavity for four days. Hybrid blocks, 4 mm × 4 mm wide × 2–mm thick, were luted with resin cements on dentin surface and then the specimens were subjected to shear bond strength testing. Analysis of variance and Tukey post hoc multiple comparison tests were applied ( P < .05). Results: G2 and G4 showed significantly low bond strength values and they were lower than the other groups ( P < .05). There were no significant differences between G1, G3, and G6 ( P > .05). The pH values had risen markedly in the groups containing calcium hydroxide (G4 and G5) after four days ( P < .05). Conclusion: The application of 10% SA or 10% SA and CaOH2 mixture were effective at reversing bleaching effects on bond strength. CaOH2 or CaOH2 and 10% SA mixture increased the external medium pH and were effective for alkalinization after intracoronal bleaching.

Over 200 million people in over 35 countries are affected by excessive fluoride in their waters. For people that do not have access to a centralized water treatment plant, there is a need for an on-site defluoridation system that requires no special operational expertise, does not use hazardous chemicals, and is sustainable by the local population. 8 different calcium phosphate precipitation systems were analyzed and tested for fluoride removal effectiveness. An effective system would have final fluoride concentrations less than 1.5 mg/L and final solutions with pH within drinkable limits. Phosphoric acid with the addition of a calcium carbonate source was found to have a 99.8% fluoride removal rate. Monosodium phosphate with addition of slaked lime was also found to be effective with a 99.98% fluoride removal rate. An optimal slaked lime to monosodium phosphate ratio that achieved effective fluoride removal and neutral pH was found. With 0.45 g of Ca(OH)2 and 1 g of NaH2PO4, initial fluoride concentrations up to 100 mg/L or more could be reduced to near zero concentrations, and a volume of approximately 337 mL of water with a concentration of 5 mg/L F- could to be reduced to less than 1.5 mg/L F-.

Aim: One of the main steps in a successful endodontic treatment is determining the correct working length (WL) of the root canal. In this regard, electronic apex locators (EAL) have been widely used for measuring the WL. The accuracy of EALs in determining the WL may be influenced by various factors. This study is aimed to evaluate the effects of apical patency, coronal preflaring, and calcium hydroxide on the accuracy of the EAL. Materials and Methods: In this in vitro study, 20 central incisor single-rooted human teeth with fully formed apex were considered. Then, samples were randomly divided into two study groups, ten samples in each group. The WL was determined and recorded at 0.5 mm distance to the apex using Root ZX apex locator before and after creating patency, coronal preflaring, and calcium hydroxide administration. All WLs were measured separately for each tooth and reviewed independently by two experienced operators with extensive experience in using EALs. Paired t test and Wilcoxon signed-rank test were applied and the significant level was at .05. Results: Statistical analysis of the obtained data showed a significant decline in the WL after apical patency and coronal preflaring ( P < .05). Moreover, WL exhibited a significant enhancement after calcium hydroxide application ( P < .05). Conclusion: Apical patency and coronal preflaring increased the accuracy of apex locators in determining the WL of the teeth. Besides, calcium hydroxide residues in the root canal reduced the accuracy of the apex locator.

Aim To develop a formulation in which calcium hydroxide (Ca(OH)₂) was successfully loaded into poly(lactic-co-glycolic acid) (PLGA) biodegradable nanoparticles (NPs) to be used in the field of endodontics as an intracanal medicament, including NP optimization and characterization, plus drug release profile of the NPs compared with free Ca(OH)₂. Additionally, the depth and area of penetration of the NPs inside the dentinal tubules of extracted teeth were compared with those of the free Ca(OH)₂. Methodology Ca(OH)₂ NPs were prepared using the solvent displacement method. NPs was optimized with a central composite design to obtain a final optimized formulation. The morphology of the NPs was examined under transmission electron microscopy (TEM), and characterization was carried out using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC). The drug release profile of the Ca(OH)₂ NPs and free Ca(OH)₂ was evaluated up to 48 h. Finally, the depth and area of penetration inside the dentinal tubules of extracted teeth were examined for both the Ca(OH)₂ NPs and free Ca(OH)₂ using the Mann-Whitney U test to determine any significant differences. Results Utilizing the optimized formulation, the Ca(OH)₂ NPs had an average size below 200 nm and polydispersity index lower than 0.2, along with a highly negative zeta potential and suitable entrapment efficiency percentage. The spherical morphology of the Ca(OH)₂ NPs was confirmed using TEM. The results of the XRD, FTIR and DSC revealed no interactions and confirmed that the drug was encapsulated inside the NPs. The drug release profile of the Ca(OH)₂ NPs exhibited a prolonged steady release that remained stable up to 48 h with higher concentrations than the free Ca(OH)₂. After examination by confocal laser scanning microscopy, Ca(OH)₂ NPs had a significantly greater depth and area of penetration inside dentinal tubules compared with the free drug. Conclusions Ca(OH)₂-loaded PLGA NPs were successfully optimized and characterized. The NPs exhibited a prolonged drug release profile and superior penetration inside dentinal tubules of extracted teeth when compared to Ca(OH)2 .

Introduction: intracanal medicaments have an important role in disinfecting ofthe pulp space and in endodontic regenerative procedures. These medications comein close contact with the periradicular tissue, thus their degradation products must bebiocompatible with the periapical tissue. Otherwise, these medicaments will resultin intense inflammatory reaction. Aim of the study: The purpose of this in vitrostudy was to evaluate and compare the cytotoxicity of three intracanal medications;Neem oil, double antibiotic paste (DAP) and calcium hydroxide (Ca(OH)2).Materials and Methods: Immortalized human gingival fibroblast cells were retrievedfrom the cell bank and then cultured. Three different intracanal medications (Neemoil, DAP, Ca(OH)2) were added to the cultured cells. Cell viability was evaluatedusing 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) andApoptosis/necrosis assays. Statistical analysis was performed using One-way ANOVAand post-hoc Tukey test. Results: Ca(OH)2 recorded the highest significant cytotoxicityfollowed by Neem oil, then DAP which recorded the lowest significant cytotoxicity.Cytotoxicity of the three intracanal medicaments used were directly proportional totheir concentrations Conclusion: DAP could be better recommended as intracanalmedicament in regenerative endodontic procedures because of its biocompatibilitycompared to the other tested medications.

Objective: To assess the post-operative pain by using calcium hydroxide Ca(OH)2 based root canal sealer, a clinical study at tertiary care Hospital Materials and Methods: This cross-sectional study was performed at operative dentistry department of Liaquat University of Medical and health Sciences Jamshoro Pakistan. Study duration was 6 months from March 2020 August 2020. Total 60 patients, those having permanent anterior teeth with irreversible pulpitis, teeth restoration after root canal treatment and either of gender were included. Multiple visits of endodontic treatment were performed by obturating the canals using calcium hydroxide Ca(OH)2 (sealapex, Sybron endo). Patients were recalled next day, after 3rd day and after one week of obturation to assess the severity of post-operative pain (POP) via visual analogue scale (VAS). All the information was recorded via study proforma. Data analysis was done by using SPSS version 20. Results: Mean age of the study participants was 26.77+8.72 years. males were in majority 36(60.0%). On the next day as per severity of pain, mostly patients were presented with severe pain as mean visual analogue scale was 8.7+0.3. On third day pain was markedly decrease among almost all of the cases as average of visual analogue scale was found 2.6+0.2. However after one all the patients were seen without pain as average of visual analogue scale was 0.65+0.7. Pain was statistically insignificant according to gender. Conclusion: Calcium hydroxide based root canal sealer found to be feasible and effective for endodontic treatment in terms of lower postoperative pain.

Recurrent endodontic infections of treated teeth are mainly linked to microbial persistency in the root canal system. Enterococcus faecalis is a bacterium that is often identified in these recurrent infections. Calcium hydroxide (Ca(OH)2) is a widely used root canal medicament and is now being developed to be produced from natural materials. Ca(OH)2, which is synthesized from natural limestone from Palimanan, Indonesia, has a structure similar to Ca(OH)2, which is often used as a root canal medicament. The purpose of this study was to determine the antimicrobial property of Ca(OH)2 paste synthesized from natural limestone compared to conventional Ca(OH)2 paste. This study is an in vitro experimental study consists of 3 groups (n=24, namely, conventional Ca(OH)2 paste, limestone synthesized Ca(OH)2 paste, and saline as the negative control, for 2 intervals of time and evaluated by Total Plate Counting (TPC) method. Samples were mandibular first premolar root canal prepared by root canal preparation and contaminated with E. faecalis (ATCC 29212). The infected root canals of each group were treated by the medicaments, and samples from the root canals were taken on day 7 (n=4) and 14 (n=4). Results showed that both Ca(OH)2 groups had antimicrobial activities against E. faecalis. The limestone Ca(OH)2 paste group had the least amount of bacterial colonies on the 7th day compared to other groups. In contrast, on the 14th day, the conventional Ca(OH)2 paste had the least bacterial colonies. It can be concluded that the Ca(OH)2 paste synthesized from natural limestone has an antimicrobial effect on E. faecalis, the antimicrobial effect was higher on the 7th day but decreases on the 14th day, whereas the conventional Ca(OH)2 had a higher antimicrobial effect on day 14 compared to day 7. Further studies are expected to improve the long-term antimicrobial effectiveness and sustainability of the natural limestone synthesized Ca(OH)2 paste.

Calcium hydroxide (Ca(OH)2 has been recently synthesized from natural Indonesian limestone to be used as an intracanal medicament for root canal infection. Ca(OH)2 is applied into the infected root canal in a non-setting paste form to release calcium and hydroxyl ions which elevates the pH and provide an antimicrobial effect to pathogenic bacteria. To form an injectable paste, Ca(OH)2 powder has to be mixed with a proper solvent to produce optimal consistency, ion dissociation, and maintain its property as a non-set material. Solvent is an important factor affecting ion dissociation and preserving its non-setting paste condition. The aim of this study is to synthesize Ca(OH)2 powder from Indonesian limestone, and evaluate the setting time of Ca(OH)2 paste from mixture of Ca(OH)2 powder synthesized from Indonesian limestone (limestone Ca(OH)2) with various solvent, to evaluate which solvent serve best to prevent the Ca(OH)2 paste from setting, to form an ideal paste be used as an intracanal medicament. This study consists of 5 groups (n=5); commercially Ca(OH)2 paste (Calcipex II) as positive control, Ca(OH)2 powder (Merck) + distilled water as negative control, limestone Ca(OH)2 powder + natrium carboxy methylcellulose (Na CMC) as group 1, limestone Ca(OH)2 powder + propylene glycol (PG) as group 2, and limestone Ca(OH)2 powder + polyethylene glycol (PEG) as group 3. Setting time evaluation was measured according to ISO 9917 by vicat needle in 37°C to mimic the physiological body condition. Results were analyzed by One Way Anova test and Post Hoc Tukey test. The result of this study showed that the setting time of Ca(OH)2 paste mixed with Na CMC solvent was 1:04 hours, PG 72:15 hours, and PEG did not harden until 7 days of observation. PEG is a hygroscopic high viscosity solvent, resulting in low and steady molecule interaction, thus prolonged its setting time. From this study it can be concluded that PEG inhibit Ca(OH)2 setting reaction up to 7 days and might be used as solvent for Ca(OH)2 paste as intracanal medicament.

This study aimed to compare the effect of XP-endo Finisher file (XPF), passive ultrasonic irrigation (PUI) and conventional irrigation technique using side-vented needle (SVN) on the amount of apically extruded debris after the removal of calcium hydroxide Ca(OH)2 and double antibiotic paste (DAP). Materials and Methods: Sixty extracted human mandibular premolars were used. After decronation, all canals were prepared up to the ProTaper Next X4 file (Dentsply Maillefer, Ballaigues, Switzerland). After dryness, teeth were randomly assigned into 2 groups (n=30) according to the Type of intracanal medication used; Ca(OH)2 and DAP then incubated at 37 °C and 100% humidity. After one week, Samples in each group were randomly assigned to 3 subgroups (n=10) according to the method used for medicament removal: XPF, PUI and SVN. Debris extruded during the removal procedure were collected into pre-weighed Eppendorf tubes then left to dry in an incubator at 37°C for 15 days. The amount of extruded debris was assessed with an analytical balance and calculated by subtracting the initial weight from the final weight of the tube. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U test. Results: there was no statistically significant difference regarding the amount of apically extruded debris after using the three irrigation techniques in removal of both Ca(OH)2 and DAP (P-value = 0.141, Effect size = 0.160) and (P-value = 0.237, Effect size = 0.073) respectively. Conclusions: Neither XPF nor PUI increase the risk of intracanal medicament extrusion beyond the apex.