• Title/Summary/Keyword: Calcium Hydroxide

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AN INFRA-RED SPECTROPHOTOMETRIC STUDY OF THE REACTION IN CALCIUM HYDROXIDE DENTAL CEMENT (치과용(齒科用) 수산화(水酸化)칼슘 시멘트의 경화반응(硬化反應)에 관(關)한 적외선분석학적(赤外線分析學的) 연구(硏究))

  • Kim, Choong-Jong;Min, Byung-Soon;Choi, Ho-Young;Park, Sang-Jin
    • Restorative Dentistry and Endodontics
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    • v.10 no.1
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    • pp.71-83
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    • 1984
  • The purpose of this study was to evaluate the transmission spectrum of the set calcium hydroxide dental cement (Dycal, L.D. Caulk Co. Milford, Del.) Cement was prepared for A T R spectra at a low powder-to-liquid ratio of 3.0gm/ml in order to retard the reaction and facilitate the manipulation of loading the cement into the cell. Spectra were recorded on an I R Spectrophotometer (MX-1, FT) at an agle of incidence of 55. The A T R cell was a RIIc Model TR5 with a hemisperical KRS-5 (Thallium-Bromide-Iodide). A spectrum was recorded within 3 minutes. Further spectra were recorded after 5,10,30 minutes and 1,5,24, 72 hours. The results were as follows; 1. The setting reaction between acid paste and base past would take place fastly within 10 minutes after mix, and that would be slow until 72 hours after mix. 2. In the set cements, some methyl salicylate and calcium hydroxide remained unreacted until 72 hours after mix. 3. The setting reaction and the reaction rate occuring at the surface and in the bulk cements were similar. 4. The chelates were bound together between calcium hydroxide and methyl salicylate.

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Quantitative Analysis of Hydrate products of the Cement Paste Mixed with Admixtures (혼화재 혼입 시멘트 페이스트의 수화생성물 정량 분석)

  • Park, Dong-Cheon
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2021.11a
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    • pp.176-177
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    • 2021
  • In order to compensate for the defects of concrete made using only Portland cement, three-component powder mixed with blast slag and fly ash, and four-component powder concrete mixed with silica fume are being produced. When each of the admixtures is used alone, the above-described excellent performance is expressed and up to 70% of the powder is used. These technologies are also contributing to the reduction of greenhouse gases under Act on Low Carbon. Green Growth. However, calcium hydroxide is consumed as a stimulator or reaction in the case of silica fume, which causes latent hydroponicity of slag, pozzolane reaction, and silica mixtures represented by fly ash. It is known that the consumption of calcium hydroxide affects the alkalinity of concrete. As a result, the carbonation resistance is significantly lower among the durability of concrete. Research on quantification of such effects is insufficient. In this study, an experiment was conducted to quantify calcium hydroxide of the three-component and four-component powder paste using thermal analysis equipment (DTG), and the effect of the mixing amount was discussed.

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Development of Soil Binder Using Plant Extracts (식물추출액을 이용한 지반 고결제 개발)

  • Park, Sung-Sik;Choi, Sun-Gyu;Nam, In-Hyun
    • Journal of the Korean Geotechnical Society
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    • v.28 no.3
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    • pp.67-75
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    • 2012
  • This paper presents an environment-friendly sand cementation method by precipitating calcium carbonate using plant extracts. The plant extracts contain urease like $Sporosarcina$ $pasteurii$, which can decompose urea into carbonate ion and ammonium ion. It can cause cementation within sand particles where carbonate ions decomposed from urea combine with calcium ions dissolved from calcium chloride or calcium hydroxide to form calcium carbonate. Plant extracts, urea and calcium chloride or calcium hydroxide were blended and then mixed with Nakdong River sand. The mixed sand was compacted into a cylindrical specimen and cured for 3 days at room temperature ($18^{\circ}C$). Unconfined compression test, SEM and XRD analyses were carried out to evaluate three levels of urea concentration and two different calcium sources. As urea concentration increased, the unconfined compressive strength increased up to 10 times those without plant extracts because calcium carbonate precipitated more, regardless of calcium source. It was also found that the strength of specimen using calcium chloride was higher than that of specimen using calcium hydroxide.

TOXIC EFFECT OF ADHESIVE RESINS ON THE DOG'S PULP TISSUE (접착성(接着性) 레진이 가견치수조직(家犬齒髓組織)에 미치는 독성(毒性)에 관(關)한 실험적(實驗的) 연구(硏究))

  • Son, Ho-Hyun
    • Restorative Dentistry and Endodontics
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    • v.10 no.1
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    • pp.31-42
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    • 1984
  • The toxic effect of adhesive resins on the dog's pulp tissue was studied with 70 teeth from 5 dogs. The experimental materials were Clearfil, a mixture of Clearfil with calcium hydroxide powder, Panavia-EX, and a mixture of Panavia-EX with calcium hydroxide powder. As a control group, calcium hydroxide powder was used. Each material was placed on the pulpotomized tissue surface. After 3 days, 1, 2,4, and 6 weeks, the teeth and apical tissue were processed routinly and stained with hematoxylin and eosin. Pathological tissue changes due to the toxicity of adhesive resins were observed by light microscope, and the pH of Panavia-EX and the Bonding agent of Clearfil were measured. Following were the results; 1. In the group of calcium hydroxide powder, slight inflammatory change was observed in the pulpotomized surface and adjacent pulp tissue on 3 day. 1 week case showed incomplete dentin bridge. The remaining pulp tissue was normalized according to the days elapsed. 2. In the group of Clearfil, early inflammatory change revealed in the superificial portion of the remaining pulp tissue on 3 day. The inflammation spreaded over the total pulp tissue and partial necrosis was observed in 1 week and 2 week cases. Total necrosis of pulp tissue and moderate inflammatory change at the apical tissue was noticed in 4 week and 6 week cases. 3. In the group of Panavia-EX, moderate inflammatory change appeared in the superficial pulp tissue on 3 day, and severe inflammatory change over all pulp tissue found in 1 week case. Pulp necrosis was obvious in 2 week case. 4 week and 6 week cases were totally necrotized up to the periapical tissue. 4. In the groups of mixtures with calcium hydroxide powder, the pulp tissue destruction was retarded, compared with the groups of Clearfil and Panavia-EX. 5. Panavia-EX was more destructive than Clearfil. 6. The acidity of freshly mixed Bonding agent of Cleafil was pH 4.0, and that of Panavia-EX was pH 2.0.

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Synthesis and Crystallization of Amorphous Calcium Carbonate by Gas-Liquid Reaction of System Ca($OH_2 O$)-$H_2$-$CO_2$ (Ca($OH_2$)-$H_2 O$-$CO_2$계의 기액반응으로부터 비정질 탄산칼슘의 합성 및 결정화)

  • Im, Jae-Seok;Kim, Ga-Yeon;Im, Goeng
    • The Journal of Engineering Research
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    • v.5 no.1
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    • pp.73-87
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    • 2004
  • The synthesis and crystallization of amorphous calcium carbonate($CaCO_3$.$nH_2 O$) obtained from gas-liquid reaction between aqueous solution of calcium hydroxide and carbon dioxide at 15~$50^{\circ}C$ are investigated by electrical conductometry, XRD and TEM. The results are as follows: The initial reaction products prior to the formation of precipitated calcium carbonate is amorphous calcium carbonate. The electrical conductivity values in the slurry are decreased during the formation of amorphous calcium carbonate which covers particle surface of calcium hydroxide and retard the dissolution of calcium hydroxide into the solution. that amorphous calcium carbonate is unstable in the aqueous solution and crystallizes finally to calcite by the through-solution reaction. While amorphous calcium carbonate crystallizes into chain-like calcite, the conductivity values are recovered rapidly and the apparent viscosity of slurry containing higher concentration of calcium hydroxide increase. At below pH 9.5, chain-like calcite separates into individual particles to form precipitated calcium carbonate. The formation and synthetic temperature range of amorphous calcium carbonate is most suitable a primary decreasing step(a-step) at $15^{\circ}C$ in the electrical conductometry.

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Consolidation to Bulk Ceramic Bodies from Oyster Shell Powder (굴 패각 분말로부터 벌크 세라믹 구조체 제조)

  • Cho, Kyeong-Sik;Lee, Hyun-Kwuon;Min, Jae Hong
    • Journal of Powder Materials
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    • v.23 no.3
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    • pp.221-227
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    • 2016
  • Waste oyster shells create several serious problems; however, only some parts of them are being utilized currently. The ideal solution would be to convert the waste shells into a product that is both environmentally beneficial and economically viable. An experimental study is carried out to investigate the recycling possibilities for oyster shell waste. Bulk ceramic bodies are produced from the oyster shell powder in three sequential processes. First, the shell powder is calcined to form calcium oxide CaO, which is then slaked by a slaking reaction with water to produce calcium hydroxide $Ca(OH)_2$. Then, calcium hydroxide powder is formed by uniaxial pressing. Finally, the calcium hydroxide compact is reconverted to calcium carbonate via a carbonation reaction with carbon dioxide released from the shell powder bed during firing at $550^{\circ}C$. The bulk body obtained from waste oyster shells could be utilized as a marine structural porous material.

A preliminary report on histological outcome of pulpotomy with endodontic biomaterials vs calcium hydroxide

  • Nosrat, Ali;Peimani, Ali;Asgary, Saeed
    • Restorative Dentistry and Endodontics
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    • v.38 no.4
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    • pp.227-233
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    • 2013
  • Objectives: The purpose of the study was to evaluate human dental pulp response to pulpotomy with calcium hydroxide (CH), mineral trioxide aggregate (MTA), and calcium enriched mixture (CEM) cement. Materials and Methods: A total of nine erupted third molars were randomly assigned to each pulpotomy group. The same clinician performed full pulpotomies and coronal restorations. The patients were followed clinically for six months; the teeth were then extracted and prepared for histological assessments. The samples were blindly assessed by an independent observer for pulp vitality, pulp inflammation, and calcified bridge formation. Results: All patients were free of clinical signs/symptoms of pulpal/periradicular diseases during the follow up period. In CH group, one tooth had necrotic radicular pulp; other two teeth in this group had vital uninflamed pulps with complete dentinal bridge formation. In CEM cement and MTA groups all teeth had vital uninflamed radicular pulps. A complete dentinal bridge was formed beneath CEM cement and MTA in all roots. Odontoblast-like cells were present beneath CEM cement and MTA in all samples. Conclusions: This study revealed that CEM cement and MTA were reliable endodontic biomaterials in full pulpotomy treatment. In contrast, the human dental pulp response to CH might be unpredictable.

Corrosion control technology in water pipes by adjusting the corrosivity of drinking water : effect and impact of the lime dispersion system (수돗물 부식성 제어를 통한 수도관 부식방지기술: 석회수 분산화장치를 이용한 미네랄 공급 효과와 영향 분석)

  • Han, Keum-Seok;Park, Young-Bok;Kim, Seong-Jae;Kim, Hyen-Don;Choi, Young-June;Park, Ju-Hyun;Woo, Dal-sik;Hong, Seong-Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.32 no.3
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    • pp.235-242
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    • 2018
  • Corrosion inhibitors including calcium hydroxide have been used to prevent corrosion in the pipes for tap water supply. The corrosion index (i.e., Langelier Index) differs by area and water quality. The corrosion indices of the areas studied differed by more than 2.0. The 'homogenized' calcium hydroxide was added to the treated water at the K water treatment plant, in order to increase the value of the corrosion index and the concentration of calcium. As the result, the concentration of calcium was increased while the turbidity and pH changed little. The corrosion rate of the tap water with the 'homogenized' calcium hydroxide could be slowed down pretty much. The results suggested that the technology of 'homogenization' of calcium hydroxide can applied to tap water and desalinated water to prevent corrosion in water pipes even in corrosive pipes.

Synthesis and Shape Control Calcium Hydroxide Fine Powders by Hydration of Calcium Oxide (산화칼슘의 수화에 의한 수산화칼슘 미분말의 합성과 형상제어)

  • 민경소;최상흘
    • Journal of the Korean Ceramic Society
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    • v.28 no.9
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    • pp.739-749
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    • 1991
  • Calcium hydroxide fine powders were synthesized by hydration of calcium oxide, and the shapes of powders obtained were examined for each synthethic condition. When distilled water was used as a solvent, irregular and agglomerated submicron powders were obtained, and it was impossible to control of the shapes. In methanol-added solutions, hexagonal plate-like particles were obtained, but addition of ethanol had no effect. However on the occasion that substituted ethylene glycol for ethanol of 5 vol%, hexagonal plate-like powders were obtained. The shapes of powders synthesized in acetic acid and salicylic acid solutions were hexagonal platelike, and were spherical and very fine in citric acid and oxalic acid solutions, respectively. But in some solutions, calcium salts were precipitated by the reaction between calcium and acid added. And the size of powders were very fine using ultrasonic vibration instead of mechanical agitation.

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Effects of Calcium Hydroxide as an Intracanal Medicine on Sealers.

  • Hosoya, N.;Takahashi, G.;Kurayama, H.;Tahata, K.;Arai, T.
    • Proceedings of the KACD Conference
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    • 2001.11a
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    • pp.565.2-565
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    • 2001
  • Calcium hydroxide is unavoidably left on the root canal wall when used as an intracanal medicament, and is assumed to have some undesirable influence on the canal sealers. The purpose of this study was to determine whether the $Ca(OH)_2$ change physical properties (Exp. I) and sealing ability (Exp. II) of root canal sealers. Exp. I: As calcium hydroxide agents, $Calcipex^{\circledR}, {\;}Vitapex^{\circledR}, {\;}Calxyl^{\circledR}, {\;}and{\;}Ca(OH)_2$ were used.(omitted)

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