• The Journal of Advanced Prosthodontics
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• v.6 no.1
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• pp.60-65
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• 2014

Teeth that have short clinical crown, which are not alone enough to support the definitive restoration can be best treated using the post and core system. The advantages of fiber post over conventional metallic post materials have led to its wide acceptance. In addition to that the combination of aesthetic and mechanical benefits of fiber post has provided it with a rise in the field of dentistry. Also the results obtained from some clinical trials have encouraged the clinicians to use the fiber posts confidently. Fiber posts are manufactured from pre-stretched fibers impregnated within a resin matrix. The fibers could that be of carbon, glass/silica, and quartz, whereas Epoxy and bis-GMA are the most widely used resin bases. But recently studies are also found to be going on for polyimide as possible material for the fiber post resin base as a substitute for the conventional materials.

• Bulletin of the Korean Chemical Society
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• v.22 no.6
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• pp.570-574
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• 2001

Magnesium isotope separation was investigated by chemical ion exchange with the 1-aza-12-crown-4 bonded Merrifield peptide resin using an elution chromatographic technique. The capacity of the novel azacrown ion exchanger was 1.0 meq/g dry resin. The heavier isotopes of magnesium were enriched in the resin phase, while the lighter isotopes were enriched in the solution phase. The single stage separation factor was determined according to the method of Glueckauf from the elution curve and isotopic assys. The separation factors of $^{24}Mg^{2+}$-$^{25}Mg^{2+}$, $^{24}Mg^{2+}$-$^{26}Mg^{2+}$, and $^{25}Mg^{2+}$-$^{26}Mg^{2+}$ were 1.008, 1.019, and 1.006, respectively.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.142-147
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• 2010

Cryptand resins have been synthesized from 1-aza-18-crown-6 macrocyclic ligand attached to styrene (2th petroleum in 4th class hazardous materials) divinylbenzene copolymer with crosslinkage of 1%, 2%, 10%, and 18% by substitution reaction. The synthesis of these resins was confirmed by the content of chlorine, element analysis, surface area (BET), and IR-spectroscopy. The effects of pH, time and crosslinkage on adsorption of metal ion from water fire extinguishing agentby synthetic resin adsorbent were investigated. Metal ions showed a great adsorption over pH 3 and adsorption equilibriumof metal ions was about two hours. The adsorption selectivity determined in water was in the increasing order of sodium ($Na^{1+}$) > zinc ($Zn^{2+}$) > chromium ($Cr^{3+}$) ion. The adsorption was in the order of 1%, 2%, 10%, and 18% crosslinkage resin.

• Analytical Science and Technology
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• v.17 no.2
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• pp.91-97
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• 2004

Cryptand ion exchange resins were synthesized with 1-aza-15-crown-5 macrocyclic ligand attached to styrene divinylbenzene (DVB) copolymer with crosslink of 1%, 2%, 5% and 10% by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium ($UO{_2}^{2+}$) ion were investigated. The uranium ion was showed fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium ($UO{_2}^{2+}$), magnesium ($Mg^{2+}$), neodymium ($Nd^{3+}$) ion. The adsorption was in order of 1%, 2%, 5%, and 10% crosslink resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• Journal of dental hygiene science
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• v.22 no.3
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• pp.139-147
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• 2022

Background: Temporary crown resins are used prior to prosthesis placement, indicating the importance of aesthetics. The aim of this study was evaluate the color stability of various staining solutions according to the color of temporary crown resins using VITA Easyshade^Ⓡ V. Methods: The temporary crowns used were the powder-liquid type and included four shades. A total of 36 specimens were fabricated in the form of disks with a diameter of 1.8 mm and a depth of 2 mm. They were divided into four groups of nine each, and staining was performed for seven days by precipitation in 3 mL of three staining solutions composed of distilled water, black coffee, and red wine. Color and color stability evaluations were performed by a trained examiner using a digital spectrophotometer (VITA Easyshade^Ⓡ V). Color stability was analyzed using the ΔE value. Results: Because of the color stability evaluation using the ΔE value, the difference between three and seven days was significant in the specimen I and III groups (p<0.05). Further, post hoc analysis showed that the ΔE value of red wine was significant, indicating that the color stability in red wine was low. The ΔE values in group II between days three and seven were statistically significant (p<0.05). Post hoc analysis showed that distilled water, coffee, and wine had the highest ΔE values on day three. On day seven, the ΔE value for wine was significant, and the color stability was low. There was no significant difference in group IV according to the staining period and staining solution; therefore, color stability was high (p>0.05). Conclusion: This study showed that most temporary resin restorations exhibited color stability in the staining solution. The darker the color of the temporary resin restoration, the higher the color stability against extrinsic staining.

• Analytical Science and Technology
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• v.22 no.1
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• pp.92-100
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• 2009

Azacrown resins were synthesized by mixing 1-aza-12-crown-4 macrocyclic ligand into styrene (2th petroleum in 4th class hazardous materials) divinylbenzene (DVB) copolymer with crosslinkage of 1%, 2%, 5% and 10% by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, thermogravimetric analysis (TGA), surface area (BET), and IR-spectroscopy. The effects of pH, time, crosslinkage of resins and dielectric constant of solvent on adsorption of metal ions by resin adsorbent were investigated. Metal ions showed a great adsorption over pH 3 and adsorption equilibrium of metal ions was about two hours. In addition, adsorptive selectivity of metals on the resin in ethanol solvent was increased in the order of ${UO_2}^{2+}$ > $Ca^{2+}$ > $Sm^{3+}$ ion and adsorption of uranium ion was decreased with increase of crosslinkage such as 1%, 2%, 5% and 10% and was inversely proportional to the order of dielectric constant of solvents.

• Analytical Science and Technology
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• v.21 no.2
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• pp.109-116
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• 2008

Resins were synthesized by mixing 1-aza-18-crown-6 macrocyclic ligand into styrene(dangerous matter) divinylbenzene(DVB) copolymer with crosslink of 1%, 2%, 6% and 12% by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, elemental analysis, thermogravimetric analysis, electron microscopy, and IR. The effects of pH, time, crosslink of resins and dielectric constant of solvent on adsorption of uranium ion by resin adsorbent were investigated. Uranium ion showed a great adsorption above pH 3 and adsorption equilibrium of metal ions was established in about two hours. In addition, adsorptive selectivity of resin in ethanol solvent was $UO{_2}^{2+}$ > $Zn^{2+}$ > $Lu^{3+}$ ion and adsorption of uranium ion increased with the increase of the degree of crosslinking (1%~12%) and was inversely in proportional to the order of dielectric constant of solvents.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.5
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• pp.503-513
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• 2006

Statement of the problem: The cold-cured resins used in fabrication of the provisional crown and fixed partial dentures could cause pulpal damage by heat generated during exothermic polymerization reactions. Purpose: In this in vitro study investigates the how external conditions such as material of the matrix, thickness of the matrix and thickness of dentin affect the temperature of the tooth during polymerization reaction of the cold-cured resins. Material and methods : To measure the temperature of the resin, metal die was maintained to the temperature of $37^{\circ}C$ with water bath to simulate the temperature of thetooth and thermocouple was placed in the center of the metal die. Acrylic pipe was cut in height of 1, 2, 3, 6, 10 mm and placed on the metal die and mixed resin was pored in the acrylic pipe As the resin polymerized temperature was recorded with the thermometer. Temperature of the resin using matrix was recorded by using the individual tray relieved in different thickness 2, 5, 7, 10 mm. The material of the matrix was irreversible hydrocolloid impression material, vinyl polysilloxane impression material and vacuum-formed template Temperature rise of the resin using different thickness of tooth section was record ed by placing tooth section on the metal die and placing resin over the tooth section. Results : Conclusion : 1. Temperature rise increased as the thickness of the resin increased but there was no significant differences over 3 mm thickness of the resin. 2. The lowest temperature rise was showed in irreversible hydrocolloid impression material and vinyl polysilloxane impression material vacuum-formed template as in orders. 3, Temperature rise of the resin decreased regardless of the thickness of the matrix when vinyl polysilloxane impression material was used as the matrix. 4 When irreversible hydrocolloid impression material was used as matrix, the temperature rise of the resin decreased as the thickness of the matrix increased and there was no temperature rise when thickness of the matrix reached 10 mm, 5. The temperature rise of the resin did not decreased when Polypropylene vacuum-formed template was used as the matrix. 6, The temperature of the resin increased as the thickness of the dentin decreased.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.1
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• pp.48-60
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• 2003

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the occlusal depth (1.5mm, 2.0mm, 2.5mm) and axial inclination ($4^{\circ},\;8^{\circ},\;12^{\circ}$) of the lower First Molar. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. LTD., Japan). The cemented crowns were mounted on the testing jig with inclination of 30 degrees and the universal testing machine(Zwick Z020, Zwick, Germany)was used to measure the fracture strength. The results of this study were as follows : 1. The fracture strength of the ceramic crown with 2.5mm depth and $12^{\circ}$ inclination was the highest (1789 N). Crowns of 1.5mm depth and $4^{\circ}$ inclination had the lowest strength (1091 N). 2. There were no significant differences in the fracture strength by axial inclination of the same occlusal depth group. 3. Most fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth. Size of fragment was affected by the amount of occlusal reduction.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.4
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• pp.499-504
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• 2000

Amelogenesis imperfecta is defined as a genetically determined effect affecting enamel formation and may be associated with other ectodermal or systemic disorders. It is entirely an ectodermal disturbance, since the mesodermal components of the teeth are basically normal. The presentation of diverse clinical manifestations in 1:14,000 to 1:16,000. Classification of the AI types considers mode of inheritance and clinical manifestations. The most widely accepted classification system recognize three major groups; i.e., hypoplastic(thin enamel), hypocalcified(primary mineralization defect), hypomaturation(defect in enamel maturation). The treatment is that at first, genetic counselling must be practiced, and in anterior teeth, composite resin veneer or jacket crown for esthetics, and in posterior teeth, stainlees steel crown or gold onlay.