• The korean journal of orthodontics
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• v.26 no.5 s.58
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• pp.613-622
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• 1996

The purposes of this study were to evaluate and compare the frequency of ceramic bracket fracture, frequency of enamel fracture, bond fracture site, adhesive remnant index after mechanical and electrothermal debracketing, to evaluate effectiveness of high and low speed rotary instrument and ultrasonic instrument during residual adhesive remnants removal, and to measure resin film surface(percentage) using by image analyser(Leco 300). Bond fracture site, bracket fracture, and enamel surface damage were examined by scanning electron microscope. The following results were obained : 1. In the mechanical debracketing group, the bond failed predominantly at enamel-adhesive interface with the bulk of adhesive remaining on bracket base. 2. In the eletrothermal debracketing group, the bond failed predominantly at adhesive-bracket interface with the bulk of adhesive remaining on enamel surface. 3. The most effectiveness of residual resin removal was obtained by means of the resin polishing bur and the order of scratch formation was the procedure using tungsten carbide bur, ultrasonic scaler, sof-lex disc, and polishing bur. 4. The order of the resin film surface percentage was ultrasonic scaler, tungsten carbide bur, sof-lex disc, and resin polishing bur.

• The korean journal of orthodontics
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• v.34 no.4 s.105
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• pp.343-349
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• 2004

Laser-aided debonding has advantages in that the heat produced is localized and controlled, the debonding tool is not heated, and it can be used for the removal of various types of ceramic brackets, regardless of their design. However, the range of safe power usage for laser-aided debonding has not vet been confirmed. The Purpose of this study was to evaluate the histologic changes of pulpal tissue in a rabbit's incisor after Nd-YAG laser-aided ceramic bracket debonding at different levels of power. The result were as follows: 1. At 3-5W Nd-YAG laser power level and 3 seconds of exposure time, the ceramic bracket debonding procedure was not easy. At 5W of power a tie-wing fracture occurred on one bracket during debonding using Weingart plier. The histologic section of pulp represented no adverse changes. 2. At 7-13 W power level and less than 5 seconds of exposure time, the debracketing procedure was done easily and bracket facture did not occur. The histologic section of pulp represented mild and reversible changes. All the results were reversible and no pulpal degeneration or necrosis occurred. Considering the results, it appears that the laser-aided debonding technique is a safe method that does not result in irreversible pulpal changes, softens bracket bonding resin within a saie range of power and exposure time, and is useful for ceramic bracket recycling by lowering the tie- wing fracture rate.

• The korean journal of orthodontics
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• v.37 no.5
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• pp.376-385
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• 2007

Esthetic brackets which resemble the color of natural teeth have been widely used. But the frictional resistance of ceramic brackets, a typical esthetic bracket, is greater than that of metal brackets. The purpose of this study was to measure the frictional resistance of the new calcium phosphate brackets (CPB) which were recently developed and to evaluate its clinical usability by comparing the frictional differences of CPB with metal brackets and metal slot inserted ceramic brackets. Methods: Experimental groups were CPB (Hyaline II, Tomy, Tokyo, Japan), metal bracket (Kosaka, Tomy, Tokyo, Japan) and metal slot inserted ceramic bracket (Clarity, 3M Unitek, Monrovia, CA, USA). All of the brackets had 0.022-inch slot sizes. The brackets were tested with $0.019\;{\times}\;0.025$ inch stainless steel wire (3M Unitek, Monrovia, CA, USA). A biologic model was used to simulate the situation which would occur during orthodontic treatment with fixed appliances. Retraction force was applied at a speed of 5 mm/min for 30 seconds. The frictional resistance was measured on a universal testing machine (Instron 4467, Instron, Norwood, MA, USA). Results: CPB showed significantly higher friction than metal brackets (p < 0.05) and lower friction than metal slot inserted ceramic brackets (p < 0.01). Conclusions: CPB can be considered to be a useful orthodontic esthetic bracket with respect to frictional resistance, as its friction is remarkably lower than that of metal slot inserted ceramic brackets.

• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.233-244
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• 1996

The purpose of this study was to compare the shear bond strength obtained from ceramic and plastic brackets bonded with various light-cured adhesives and to evaluate their debonded failure sites. Plastic brackets, Transcend 6000, Signature and Starflre TMB brackets were bonded with Orthobond, Light Bond and Transbond on one hundred forty extracted human premolar teeth as manufacturer's descriptions. After thermocycling the brackets were debonded with an Instron universal testing machine and the debonded bracket base surfaces were inspected under stereoscope to evaluate the failure sites. Also the shear bond strength and failure patterns with different curing time and with two different source of light were compared. The results were as follows. 1. There were no statistically significant differences among the mean shear bond strength of Orthobond, Light Bond and Transbond in a same bracket group except Plastic bracket group(p<0.05). 2. The mean shear bond strength of each adhesive with different bracket groups showed statistically significant differences. Stafire TMB showed the highest shear bond strenght among the brackets in this study, but there was no statistically singnificant difference with Transcend 6000 while there was statistically significant difference with Signature.(p<0.05) 3. The various bonding failure patterns were occurred among different bracket groups but most of failure sites were bracket base -adhesive interfaces. 4. There were no statistically significant differences in shear bond strength between the groups with curing time of 10 second and 20 second, and between the groups with two different sources of light as long as sufficient light intensity(above $400mWcm^2$) were provided(p<0.05). According to the result, it should be considered in clinical use of ceramic bracket with light-cured adhesives that the shear strengths of ceramic brackets were influenced by the retention from of bracket base as well as the composition of bracket and there was no difference in the shear bond strenght among various light-cured adhesives used in this study.

• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.803-812
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• 1998

The purpose of this study was to evaluate the shear bond strength and failure mode of ceramic brackets according to the surface treatment of porcelain. Sixty Porcelain samples were randomly divided into six groups of ten samples. Then they were treated as follows: Group 1(silane only), Group 2(etching+silane), Group 3(stone+silane), Group 4(sandblasting+silane), Group 5(stone +etching+silane), Group 6(sandblasting+etching+silane) After surface treatment of porcelain, sixty Transcend 6000 brackets were bonded to the prepared porcelain surface and they were stored in $37^{\circ}C$ saline for 24 hours. An Instron universal testing machine was used to test the shear bond strength of ceramic brackets to porcelain. After debonding, bases of ceramic brackets and porcelain surfaces were examined under scanning electron microscope(SEM) to determine failure mode. Statistical analysis of the data was carried out with one-way ANOVA and Duncan's multiple range test. The results were as follows : 1. The shear bond strength of surface-treated groups 2 to 6 was higher than that of only silane-treated group 1, and there was statistical significance. (P<0.05) 2. There was no significant difference among the groups 3 to 6. (P>0.05) 3. The shear bond strength of etching-surface treated group 2 was significantly lower than those of sandblasting-surface treated group 4, complex surface treated group 5 and group 6. 4. According to the scanning electromicroscopic images, the surface roughness of sandblasting-surface treated group 4 was less than those of the group 5 and 6, but there was no significant difference in the shear bond strength. (P>0.05) As a conclusion we can have a clinically adequate bond strength when an application of silane is done after the treatment of porcelain surface with more than one way to bond ceramic bracket on the porcelain. Also, it is considered that the sandblasting and application of silane is effective for the simplication and convenience of the treatment.

• The korean journal of orthodontics
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• v.29 no.4 s.75
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• pp.445-456
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• 1999

As a result of increased education and communication, the field of orthodontics has recently been expanded to include a greater number of adult treatment procedures. With this increased demand for adult orthodontic treatment, a problem that frequently arises is the placement of appliances on teeth restored with porcelain. But conventional acid-etching is ineffective in the preparation of porcelain surface for mechanical retention of orthodontic attachments. Also, it is possible to damage on porcelain. The purpose of this study was to evaluate the effect of composite bonding materials and the porcelain surface treatment methods on shear bond strength, and to observe the porcelain fracture rates. To accomplish this purpose, this study was carried out with feldsphatic porcelain, Ceram II. Porcelain surface treatment methods were divided into intact glazed porcelain which had not treatment and surface roughening. Surface roughening by etching with Hydroluoric acid(HF), sandblasting with Microetcher II and compound treatment with etching and sandblasting. Bonding materials were Ortho-two and Transbond. All porcelain specimens were applicated with porcelain primer. 1. In comparision according to porcelain surface treatment, surface roughening groups by HF etching and sandblasting had higher shear bond than intact group. No significant difference was found in Transbond group. 2. Ortho-two group had the higher shear bond strength than that of Transbond group in B:.u etching and sandblasting. 3. E(Transbond. Intact)group had the lowest shear bond strength in all experimental group. The bond strength was higher than clinically successful bond strength. 4. Non-treated group had very higher porcelain rates than treated group. 5. This study indicates that porcelain surface-roughening may not be necessary to attachment of orthodontic brackets to porcelain surfaces.

• The korean journal of orthodontics
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• v.39 no.4
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• pp.225-233
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• 2009

Objective: The purpose of this study was to investigate the effect of thermocycling and type of porcelain restoration on shear bond strength (SBS) and mode of failure of monocrystalline ceramic brackets. Methods: A total of 60 porcelain discs were made and divided into three equal groups as follows: Ceramco 3, IPS Empress II, Zi-ceram/Vintage ZR. ceramic brackets were bonded to the prepared porcelain surfaces in the same manner. Each group was divided randomly into two subgroups: thermocycled group and non-thermocycled group (control). All samples were tested in shear mode on an universal testing machine. Results: SBS of the non-thermocycled group was clinically acceptable (Ceramco 3: $7.06\;{\pm}\;1.76\;MPa$, IPS Empress II: $7.55\;{\pm}\;2.38\;MPa$, Zi-ceram/Vintage ZR: $7.19\;{\pm}\;1.38\;MPa$). But, SBS of the thermocycled group was significantly reduced (Ceramco 3: $4.88\;{\pm}\;1.00\;MPa$, IPS Empress II: $5.46\;{\pm}\;1.35\;MPa$, Zi-ceram/Vintage ZR: $4.84\;{\pm}\;1.01\;MPa$, p < 0.05). There was no difference between the shear bond strength by type of porcelain restoration. All bonding failure occurred between bracket base and adhesive, except for 2 samples. Conclusions: The results of this study suggest that the type of porcelain restoration did not affect SBS, but thermocycling weakened SBS. Therefore, the effect of thermocycling should be considered when using ceramic brackets in practice.

• The korean journal of orthodontics
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• v.39 no.4
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• pp.213-224
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• 2009

Objective: The aim of this study was to find out whether Er:YAG laser can aid in debonding ceramic brackets, and to see what kind of method will be the most appropriate for debonding. Methods: One hundred and ninety teeth, monocrystalline brackets ($MISO^{TM}$, HT, Ansan-Si, Korea), polycrystalline brackets ($Transcend^{TM}$ series 6000, 3M Untek, Monrovia, CA, USA) and the KEY Laser3 (KavoDental, Biberach, Germany) were used. Experimental groups were classified according to the type of ceramic brackets, and the amount of laser energy (0, 140, 300, 450, 600 mJ). After applying laser on the bracket at two points at 1 pulse each, the shear bond strength was measured. The effect of heat caused by laser was measured at the enamel beneath the bracket and pulp chamber. After measuring the shear bond strength, adhesive residue was evaluated and enamel surface was investigated using SEM. Results: All ceramic bracket groups showed a significant decrease in shear bond strength as the laser energy increased. The greatest average temperature change was $3.78^{\circ}C$ on the enamel beneath the bracket and $0.9^{\circ}C$ on the pulp chamber. Through SEM, crater shape holes caused by the laser was seen on the enamel and adhesive surfaces. Conclusions: If laser is applied on ceramic brackets for debonding, 300 - 450 mJ of laser energy will be safe and efficient for monocrystalline brackets ($MISO^{TM}$), and about 450 mJ for polycrystalline brackets ($Transcend^{TM}$ series 6000).

• The korean journal of orthodontics
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• v.24 no.1 s.44
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• pp.125-134
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• 1994

This study was designed for comparison of shear bond strengths and failure patterns of four experimental groups which combinated mesh-backed metal brackets and texture based ceramic brackets (Transcend series $2000^{(TM)}$) with chemically cured resin (Mono $Lok2^{(TM)}$) and visible light cured resin $(Transbond^{(TM)})$. Brackets were bonded on the extracted human bicuspids, after etching them by manufacturer's recommand, and the shear bond strengths were measured on the Instron machine after 24 hrs passed in the $37^{\circ}C$ water bath. The results were as follows. 1. Ceramic brackets, transcend series $2000^{(TM)}$, bonded with $MonoLok2^{(TM)}$ showed statistically higher shear bond strength than mesh-backed metal brackets bonded with $MonoLok2^{(TM)}$. 2. There was no significant difference in shear bond strengths between metal and ceramic brackets bonded with $(Transbond^{(TM)})$. 3. Ceramic brackets bonded with both $(Transbond^{(TM)})$) and $MonoLok2^{(TM)}$ showed primarily fractures between brackets adhesive interface. 4. Enamel crack was not found in anyone specimen.

• The korean journal of orthodontics
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• v.24 no.4 s.47
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• pp.957-967
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• 1994

The purpose of this study was to evaluate the effects of different bases of ceramic brackets on shear bond strength and to observe failure patterns of bracket bondings. Lower bicuspid brackets whose bases designed for the macromechanical and silane treated chemical bonding those for silane treated chemical bonding, those for micromechanical bonding, and those for macromechanical bonding were tested as experimental groups, and foil mesh-backed metal brackets as a control group. All the brackets were bonded with $Mono-Lok\;2^{(TM)}$ on the labial surface of extracted human lower bicuspids after etching the enamel with $38\%$ phosphoric acid solution for 60 seconds. The shear bond strengths were measured on the universal test machine after 24 hours passed in the $37^{\circ}C$ water bath. The gathered data were evaluated and tested by ANOVA and Duncan's multiple range test, and those results were as follows. The shear bond strengths of brackets for macromechanical and chemical bonding, those for chemical bonding, and those for micromechanical bonding were not different (p>0.05), but showed statistically higher than those of metal bracket and those of ceramic bracket for micromechanical bonding(p<0.05). The shear bond strengths of ceramic bracket for micromechanical bonding showed statistically lower than those of metal bracket(p<0.05). The enamel fractures and/or ceramic bracket fractures were observed in the cases of higher bond strength than that of metal bracket. These results supported that silane treated base of ceramic bracket show higher shear bond strength than that of metal bracket, and suggested that micromechanical form of ceramic bracket bases show higher shear bond strength than that of macromechanical form.