• 대한치과교정학회지
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• 제43권3호
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• pp.141-146
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• 2013

Objective: Bonding forces of brackets to enamel surfaces may be affected by the procedures used for bleaching and enamel etching. The aim of this study was to investigate the bonding strength of orthodontic brackets to laser-etched surfaces of bleached teeth. Methods: In a nonbleached control group, acid etching (group A) or Er:YAG laser application (group B) was performed prior to bracket bonding (n = 13 in each group). Similar surface treatments were performed at 1 day (groups C and D; n = 13 in each subgroup) or at 3 weeks (groups E and F; n = 13 in each subgroup) after 38% hydrogen peroxide bleaching in another set of teeth. The specimens were debonded after thermocycling. Results: Laser etching of bleached teeth resulted in clinically unacceptable low bonding strength. In the case of acid-etched teeth, waiting for 3 weeks before attachment of brackets to the bleached surfaces resulted in similar, but not identical, bond strength values as those obtained with nonbleached surfaces. However, in the laser-etched groups, the bonding strength after 3 weeks was the same as that for the nonbleached group. Conclusions: When teeth bleached with 38% hydrogen peroxide are meant to be bonded immediately, acid etching is preferable.

• 한국의류학회지
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• 제24권3호
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• pp.385-392
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• 2000

The adsorption ability of dyes on chitin, a natural polymer was investigated for decolorization of dye wastewater. Chitin was manufactured in lab by decalcification in dilute aqueous HCI solution and deproteination in dilute aqueous NaOH solution with shrimp shells. Absorbance of residue solution of dyebaths after dye adsorptions of chitin were measured in varieties of dye concentration and dipping periods. Four kinds of dyestuffs were used, C.I.Acid Blue 29. C.I.Direct Blue 6, C.I.Reactive Orange 12 and C.I.Basic Red 18. When chtin 1g was dipped in 0.05% of dyebath with stirring, maximum adsorption ratio of each kind of dyes was exhibited as 91.6% for C.I.Acid Blue 29, 95% for C.I.Direct Blue 6, 58.2% for C.I.Reactive Orange 13 and 75.8% for C.I.Basic Red 19. It shows that chitin has better adsorption abilities of ionic dyes of acid, direct and basic dye than non-ionic reactive dye. And chitin has better adsorption abilities of anionic acid direct dyes than cationic basic dye because of the presence of nitrogen atoms. All kinds of dyestuffs used showed speedy absorption effects by chitin, so chitin can absorb much amount of dyes in 5 mimutes reach to equilibrium of adsorption in 2 hours after dipping. Basic dye was absorbed the most speedily in 5 minutes, although maximum adsorption ratio is not high. That reason can be thought that chitin surface is essentially negatively charged due to polar funtional groups.

• 한국응용과학기술학회지
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• 제15권4호
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• pp.87-93
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• 1998

In spite of various applications of chitin derivatives from waste marine sources, commercial use of chitin has been limited due to resistance to chemicals and the absense of proper solvents. We prepared chitin through decalcification, bleaching and deproteination from protunus trituberculatus shells by the application of Hackman's method. Structural and chemical properties of chitin were investigated to have proper specific surface area and particle size by IR, BET and PSA. The amount of absorbed water of chitin reached equilibrium by stirring about 15 minutes. The amount of absored water of the prepared chitin were large than the commercial chitin. When prepared chitin tested on dyeing wastewater, they showed better treatment efficiency in COD, suspended solid, and color tests than the commercial chitin. The adsorption capacity increased with decreasing particle size for the prepared chitin. Treatment efficiency for color was increased as the sitirring rate increased. Results show the possibility of the prepared chitin from waste marine sources as a treatment system for dyeing wastewater.

• 대한소아치과학회지
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• 제24권3호
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• pp.511-517
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• 1997

Tooth discoloration detracts from one's appearance and influences self-image and it is particularly true in children. Therefore, pediatric dentists are required to treat tooth discoloration manifested in children for the normal development of their psycosocial health. Three treatment modalities are currently availabler for the removal of a variety of intrinsic stains from vital teeth. These are enamel microabrasion technique using hydrochloric acid, office bleaching and home bleaching technique with carbamide. Microabrasion technique has several advantages over bleaching in that it is easy to accomplish and does not require multiple office visits or the expensive instruments and the color change seems to be permanent after treatment. The process relies on decalcification, a softening with HCl and then removal of the enamel containing the stain with rubbing. Due to the mechanism of stain removal, this method is indicated for the removal of superficial enamel stains or disc oloration only. We report four successfully treated cases by enamel microabrasion using 15% HCl and pumice. Entire clinical steps are described in detail with some discussions on the outcome.

• 한국염색가공학회지
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• 제13권1호
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• pp.38-44
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• 2001

The adsorption ability of dyes on chitin, a natural polymer was investigated for decolorization of dye wastewater. Chitin was manufactured in lab by decalcification in dilute aqueous hydrochloric acid solution and deproteination in dilute aqueous sodium hydroxide solution with shrimp shells. Absorbance of residue solution of dyebaths after dye adsorptions of chtin were measured in varieties of dye concentration and dipping periods. Three kinds of Direct dyes -C.I. Direct Red 81 (red 81), C.I. Direct Brown l(brown 1) and C.I. Direct Green 26(green 26) - were used. Red 81 and brown 1 have smaller molecular weight than green 26. The results from experimentals were of]tamed as follows: 1) Adsorption of green 26 was improved in dyebath by addition of salt, but red 81 and brown 1 were not found any improvements. 2) Smaller size of chitin particles could be absorbed much more speedy. In this experiments, the smallest range of chitin particle size was $250\mu{m}$ and less. 3) The most efficient amount of chitin for 20m1 of dyebath was 0.2g, 4) Both of red 81 and brown 1 showed good and speedy adsorption abilities as dyestuffs of over 90 percent in just one minute in dyebath of 0.01% dye concentration. But green 26 was absorbed slowly because of its large molecular weight. It took 40minutes to absorb dyestuffs of over 90 percent in dyebath of 0.01% dye concentration.

• Restorative Dentistry and Endodontics
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• 제10권1호
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• pp.55-62
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• 1984

This experimental study was made to evaluate the efficacy of root canal preparation of engine reamer versus hand reamer. Eighty extracted human teeth were prepared with the following treatments and devided into 4 groups; Group 1: Canal preparation with hand reamer, and irrigation with normal saline solution. Group 2: Canal preparation with engine reamer, and irrigation with normal saline solution. Group 3: Canal preparation with hand reamer, and irrigation with 3% hydrogen peroxide and 3.5% sodium hypochlorite solution. Group 4: Canal preparation with engine reamer, and irrigation with 3% hydrogen peroxide and irrigation with 3% hydrogen peroxide and 3.5% sodium hypochlorite solution. After decalcification, 5p. sections at levels 1-, 3-, and 5-mm from the apex were evaluated microscopically. The results were as follows; The effectiveness of hand reamer and engine reamer were equal in preparing the root canal at all levels from the apex, and were equal in normal saline solution groups, and 3% $H_2O_2$ and 3.5% NaOCl solution groups. Both in hand reaming groups and in engine reaming groups, some canal walls had still untouched portion, and canal irregularities and debris were still remained.

• 대한치과교정학회지
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• 제43권1호
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• pp.29-34
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• 2013

Objective: To examine the prophylactic potential of 3 orthodontic bonding adhesives: Fuji Ortho SC, Illuminate, and Resilience. Methods: Thirty-six Wistar Wag rats were randomly divided into 4 groups consisting of 9 rats each. One of the groups received no treatment and was used as a control. In the other groups, individual bands coated with one of the 3 adhesives were cemented to the lower incisors. Enamel samples were obtained after 6 and 12 weeks and analyzed using scanning electron microscopy in combination with energy dispersive spectrometry. Results: Six weeks after band cementation, no fluoride was found in the enamel of the lower incisors. After 12 weeks, there was no fluoride in the enamel of teeth coated with the Resilience composite. However, in the case of the Illuminate composite and the resin-modified glass ionomer Fuji Ortho SC cement, the depth of fluoride penetration reached $2{\mu}m$ and $4.8-5.7{\mu}m$, respectively. Conclusions: Fluoride ions from orthodontic adhesives can be incorporated into the surface layer of the enamel. Orthodontists may apply orthodontic adhesives, such as the Fuji Ortho SC, to reduce the occurrence of caries during orthodontic treatment with fixed appliances.

• 치과방사선
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• 제28권1호
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• pp.17-26
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• 1998

The purpose of this study was to investigate whether a radiographic estimate of osseous fractal dimension is useful in the characterization of structural changes in bone. Ten specimens of bone were progressively decalcified in fresh 50 ml solutions of 0.1 N hydrochloric acid solution at cummulative timed periods of 5, 10, 20, 30, 60 and 90 minutes, and radiographed from 0 degree projection angle controlled by intraoral parelleling device. The test set of 70 radiographs was digitized and digitally filtered to reduce film -grain noise. I performed one-dimensional variance and fractal analysis of bony profiles or scan lines. Correlation analysis quantified the relationship between variance and fractal dimension. The obtained results were as follow. 1. After the first stage of decalcification variance and fractal dimension of scan line pixel intensities generally decreased with a range of 57.94 to 12.64 and 1.59 to 1.36. 2. Correlation coefficient(r) relating variances to fractal dimensions was consistantly excellent(range r=0.90 to 0.98). 3. Variance and fractal dimension were much alike in ability to discriminate, at leat on a group basis, between control and decalcified specimens.

• 대한치과교정학회지
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• 제49권2호
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• pp.116-123
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• 2019

As an alternative to the conventional fixed appliance that uses orthodontic brackets, a simple round tube without a bonding base can be bonded to the tooth surface by covering the tube with flowable resin. In this technique, bent wires cannot be inserted into the simple tubes; therefore, repositioning of the simple tubes is often required for adjustments. To reduce repositioning of simple tubes, a dome-shaped resin covering of the simple tube can be designed with a customized in-and-out compensation, using three-dimensional computer-aided design software based on digital simulation of orthodontic tooth movement. In the present case, the use of simple tubes bonded with customized resin coverings in a Class I nonextraction case is described in a 17-year-old male, in whom moderate crowding of the anterior teeth was treated over an 8-month period. This case shows that simple tubes can be used as an alternative to brackets in some Class I nonextraction cases, with the potential benefit of reducing decalcification.

• Journal of Chest Surgery
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• 제57권5호
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• pp.496-499
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• 2024

Calcification of the mitral valve annulus is common in patients on dialysis. The growing number of individuals receiving dialysis has been accompanied by an increase in cases necessitating surgical intervention for mitral valve annulus calcification. In this report, we present a severe case characterized by bulky calcification of the mitral annulus, which was managed with mechanical mitral valve replacement. A 61-year-old man on dialysis presented with chest pain upon exertion that had persisted for 3 months. Cardiac echocardiography revealed severe mitral stenosis and regurgitation, accompanied by cardiac dysfunction. During surgery, an ultrasonic aspiration system was employed to remove the calcification of the mitral valve annulus to the necessary extent. Subsequently, a mechanical mitral valve was sutured into the supra-annular position. To address the regurgitation, the area surrounding the valve was sewn to the wall of the left atrium. Postoperative assessments indicated an absence of perivalvular leak and demonstrated improved cardiac function. The patient was discharged on postoperative day 22. We describe a successful mitral mechanical valve replacement in a case of extensive circumferential mitral annular calcification. Even with severe calcification extending into the left ventricular myocardium, we were able to minimize the decalcification process. This approach enabled the performance of mitral mechanical valve replacement in a high-risk patient on dialysis, thus expanding the possibilities for cardiac surgery.