• The korean journal of orthodontics
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• v.22 no.2 s.37
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• pp.449-474
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• 1992

The purpose of this study was to evaluate the in vitro shear bond strengths to enamel and the failure sites of three ceramic brackets and one metal bracket in combination with light cured orthodontic adhesive. The brackets were divided into four groups. Each ceramic bracket group had different bonding mechanisms with adhesive. Group A; metal bracket with foil-mesh base (control group) Group B; ceramic bracket with micromechanical retention Group C; ceramic bracket with chemical bonding Group D; ceramic bracket with mechanical retention and chemical bonding. Forty extracted human lower first premolars were prepared for bonding and 10 brackets for each group were bonded to prepared enamel surfaces with $Transbond^{\circledR}$ light cured ortho dontic adhesive. Twenty four hours after bonding, the Instron universal testing machine was used to test the shear bond strength of brackets to enamel. After debonding, brackets and enamel surfaces were examined under stereoscopic microscope to determine the failure sites, Statistical analysis of the data was carried out with ANOVA test and $Scheff\acute{e}$ test using SPSS PC+. The results were as follows. 1 . There were statistically significant differences in mean shear bond strengths of three ceramic bracket groups (p < 0.05). Shear bond strengths of group C and D were significantly higher than that of group B and shear bond strength of group C was significantly higher than that of group D. 2. Group C and D both had significantly higher shear bond strengths than metal bracket (group A), but there were no significant differences in shear bond strengths between group A and B (p < 0.05). 3. The failure sites of four bracket groups were also different. Group C and D failed primarily at enamel-adhesive interface, but group A and B failed primarily at bracket base-adhesive interface. 4. Among all ceramic bracket groups, group B was very similar to metal bracket in the aspect of shear bond strength and failure site.

• 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.

• Journal of Korean Dental Science
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• v.14 no.2
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• pp.69-78
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• 2021

Purpose: The primary objective of this study was to evaluate the change in the temperature of the adhesive resin in polycrystalline ceramic brackets irradiated using a diode laser at different irradiation energy levels and times. Materials and Methods: For the measurement of the temperature of the adhesive resin, it was applied at the base of the ceramic bracket, a thermocouple was placed at the center of the base surface, the bracket was placed on prepared resin specimens for light curing, and a laser was irradiated to the center of the bracket slot at 5, 7, and 10 W. For the measurement of the temperatures of the enamel under the bracket and pulp cavity, extracted premolar was fixed to a prepared mold and the ceramic bracket was bonded to the buccal surface of the premolar. The Kruskal-Wallis H test and Friedman test were used for statistical analysis. Result: At 5 W, the temperature of the adhesive resin did not reach the resin softening temperature of 200℃ within 30 seconds. At 7 W, it reached 200℃ when the ceramic bracket was irradiated continuously for 28 seconds. At 10 W, it reached 200℃ when the ceramic bracket was irradiated continuously for 15 seconds. During laser irradiation, the temperature of the enamel under the bracket increased by over 5℃ within 15 seconds. Conclusion: The use of diode laser irradiation for bracket debonding should be carefully considered because the pulp cavity temperature increases by over 5℃ within the irradiation time for resin thermal softening.

• The korean journal of orthodontics
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• v.22 no.2 s.37
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• pp.327-343
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• 1992

Metal brackets and ceramic brackets were bonded to natural teeth, porcelain crowns and gold crowns After stored in artificial saliva solution for 72 hours at $37^{\circ}C$, the shear bond strengths were measured by Instron and compared with them, the bonding sites and bracket bases were examined by scanning electron microscope and light optical stereomicroscope. The results were as follows: 1. The shear bond strengths of the group which metal brackets were bonded to natural teeth and the groups which ceramic brackets were bonded to natural teeth and porcelain crowns were comparable to each other, the shear bond strength of the group which metal brackets were bonded to gold crowns was significantly low. 2. The bond failed predominantly at the bracket base/adhesive interface with the bulk of adhesive remaining on enamel in the group which metal brackets were bonded to natural teeth. 3. The bond failed consistently at the crown/adhesive interface with all of adhesive remaining on the bracket babes in the group which metal brackets were bonded to gold crowns. 4. The bond failed at the enamel or crown/adhesive interface with the bulk of adhesive remaining on the bracket bases in the groups which cramic brackets were bonded to natural teeth and porcelain crowns. 5. The shear bond strengths of the groups which ceramic brackets were bonded to porcelain crowns were not affected by etching time.

• 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.41 no.1
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• pp.16-24
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• 2011

Objective: The purpose of this study was to determine (1) the shear bond strength (SBS) of an antimicrobial monomer-containing self-etching primer according to ceramic bracket types and (2) the bracket-adhesive failure mode using an adhesive remnant index (ARI). Methods: A total of 90 extracted human teeth were randomly divided into 6 groups. Each group consisted of one of two ceramic brackets (monocrystalline, polycrystalline) and one of three primers (Transbond XT primer, Transbond Plus SEP, Clearfil Protect Bond) with each group containing 15 specimens. The SBS was measured, and adhesive residues left on the tooth surface were assessed. Results: The SBS of polycrystalline ceramic bracket groups was Significantly higher than that of the monocrystalline ceramic bracket groups (p < 0.001). The SBS of Transbond XT primer groups was significantly higher than those of Transbond Plus SEP groups and Clearfil Protect Bond groups (p < 0.001). All the groups showed bonding failures between the bracket base and adhesive. Conclusions: The combination of a self-etching primer with a monocrystalline bracket is recommended for clinical use, considering its acceptable SBS and mode of failure.

• The korean journal of orthodontics
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• v.37 no.4
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• pp.293-304
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• 2007

The purpose of this study was to estimate the fracture resistance of commercially available ceramic brackets to torsional force exerted from arch wires and to evaluate the characteristics of bracket fracture. Methods: Lingual root torque was applied to maxillary central incisor brackets with 0.022-inch slots by means of a $022\;{\times}\;028-inch$ stainless steel arch wire. A custom designed apparatus that attached to an Instron was used to test seven types of ceramic brackets (n = 15). The torque value and torque angle at fracture were measured. In order to evaluate the characteristics of failure, fracture sites and the failure patterns of brackets were examined with a Scanning Electron Microscope. Results: Crystal structure and manufacturing process of ceramic brackets had a significant effect on fracture resistance. Monocrystalline alumina (Inspire) brackets showed significantly greater resistance to torsional force than polycrystalline alumina brackets except InVu. There was no significant difference in fracture resistance during arch wire torsional force between ceramic brackets with metal slots and those without metal slots (p > 0.05). All Clarity brackets partially fractured only at the incisal slot base and the others broke at various locations. Conclusion: The fracture resistance of all the ceramic brackets during arch wire torsion appears to be adequate for clinical use.

• The korean journal of orthodontics
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• v.39 no.4
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• pp.234-247
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• 2009

Objective: The purpose of this study was to evaluate the shear bond strength of rebonded ceramic brackets according to each condition and find an appropriate method to rebond ceramic brackets with proper shear bond strength in clinical practice. Methods: The study consisted of 12 experimental groups, according to the types of brackets, debonding methods, and treatment methods of the bracket base. Shear bond strength was measured, and adhesive residues left on the tooth surface were assessed. The base of the bracket was examined under scanning electron microscopy. Results: The shear bond strength of the monocrystalline ceramic bracket group was significantly higher than thatof the polycrystalline bracket group with only sandblasting (p < 0.05). There was no significant difference in shear bond strength between groups that used rebonded brackets which were debonded with shear force and debonded with laser (p > 0.05). The shear bond strength of the sandblasted/silane group was significantly higher than that of the selectively grinded group with a low-speed round bur and the sandblasted only group (p < 0.001). The retentive structure was more presented in groups where laser was applied than in groups where shear force was applied to debond brackets prior to rebonding. The bracket bases which were treated before rebonding presented smoother surfaces than new brackets. Conclusions: Shear bond strength could be increased by applying a silane coupling agent after sandblasting before rebonding. Also, the bond strength of the selectively grinded group with a low-speed round bur and the sandblasted group showed acceptable bond strength for clinical orthodontic treatment.

• 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.28 no.1 s.66
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• pp.43-49
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• 1998

The aim of this study were to measure and compare the stress level on three type brackets and each other material (stainless steel, ceramic) with tipping and torquing forces by using the finite element analysis and to design biomechanically favorable brackets. For this study, three kinds of brackets were selected(A:Transcend-RMO, B:Signature-Unitek, C:PAW: plain archwire appliance-applied for a patent in Yonsei Udiversity). The slot size of bracket was 0.022inch and the size of archwire was 0.0175x0.025inch and taper shaped archwire was used in PAW. Loading force in tipping was 4.27N and torquing force was 32.858N applied by archwire torsion with 19.7degree and 11.3 degree in C type bracket. The conclusions were that (1) The finite element method proved to be a useful tool in the stress analysis of orthodontic bracket subjected to various forces. (2) With tipping, the stresses were concentrated at the gingival wall of the wire slot where it meets the mesial bracket surface and the incisal wall of the wire slot where it meets the distal bracket surface and with torquing, the stresses were concentrated at the junction of the gingival or incisal wall and base of the slot. (3) The maximum stress value was higher in torquing force than tipping force and therefore it is desirable to design on the basis of torquing force. (4) It was considered that the change in material might be affect on the diminish of stress value in the place of stess concentration. (5) The maximum stress value was highest on PAW bracket when the tipping and torquing force was applied and therefore it would be desirable to use mechanically favorable material on PAW bracket.