• The korean journal of orthodontics
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• v.36 no.3 s.116
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• pp.207-217
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• 2006

Although ceramic brackets have been used widely for improved esthetics during treatment, ceramic brackets have some inherent problems; brittleness, attrition of the opposing teeth and high frictional resistance. This study was performed to understand the frictional resistance of the ceramic brackets, as well as to be a helpful reference for finding the solutions to the problem of frictional resistance. Three different kinds of brackets were used; metal bracket, polycrystalline ceramic brackets with a metal slot to reduce the high frictional resistance and monocrystalline ceramic brackets. The brackets were tested with a $.019{\times}.025$ stainless steel wire with a second order angulation of $0^{\circ}\;and\;10^{\circ}$, and the static and kinetic frictional forces were measured on the universal testing machine. The results of this study showed that the ceramic brackets, especially the monocrystalline ceramic bracket without a metal slot, generated higher frictional resistance than the metal bracket, and the frictional resistance was increased as the angulation between the bracket slot and the wire increased. Therefore, the development of the ceramic bracket with reduced frictional resistance and the prevention of excessive crown tipping during orthodontic treatment will lead to the simultaneous attainment of more efficient and improved esthetic treatment goals.

• 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.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.36 no.2 s.115
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• pp.125-135
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• 2006

The purpose of this study was to measure and compare the level of frictional resistance generated from three currently used ceramic brackets; 1, Crystaline $V^{(R)}$, Tomy International Inc., Tokyo, Japan; 2, $Clarity^{(R)}$, 3M Unitek, Monrovia, CA, USA; 3, $Inspire^{(R)}$, Ormco, Orange, CA, USA; with composite resin brackets, Spirit, Ormco, Orange, CA, USA; and conventional stainless steel brackets, Kosaka, Tomy International Inc., Tokyo, Japan used as controls. In this experiment, the resistance to sliding was studied as a function of four angulations $(0^{\circ},\;5^{\circ},\;10^{\circ}\;and\;15^{\circ})$ using 2 different orthodontic wire alloys: stainless steel (stainless steel, SDS Ormco, Orange, CA, USA), and beta-titanium (TMA, SDS Ormco, Orange, CA, USA). After mounting the 22 mil brackets to the fixture and $.019{\times}.025$ wires ligated with elastic ligatures, the arch wires were slid through the brackets at 5mm/min in the dry state at $34^{\circ}C$. Silica-insert ceramic brackets generated a significantly lower frictional force than did other ceramic brackets, similar to that of stainless steel brackets. Beta-titanium archwires had higher frictional resistance than did stainless steel, and all the brackets showed higher static and kinetic frictional force as the angulation increased. When the angulation exceeded $5^{\circ}$, the active configuration emerged and frictional force quickly increased by 2.5 to 4.5-fold. The order of frictional force of the different wire-bracket couples transposed as the angle increased. The silica-insert ceramic bracket is a valuable alternative to conventional stainless steel brackets for patients with esthetic demands.

• The korean journal of orthodontics
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• v.37 no.5
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• pp.341-350
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• 2007

The purpose of this study was to evaluate how the friction that occurs during the sliding movement of the archwire through esthetic brackets is differently affected by bracket materials, slot designs, and tip angulations of the archwire. Methods: Eight types of brackets with 0.018 inch slots (composite: Brillant (BR); composite with metal slot: Spirit MB (SP); ceramic: Inspire (IN), Signature (SI), Cristaline V (CR); ceramic with metal slot: Clarity (CL), Luxi II (LU); and metal bracket: Integra (IT)), and placed into groups of 20 brackets in each group, were tested in artificial saliva with 0.018 inch stainless steel wire. The wire tip angulations were given as 0, 4 and 8 degrees. Results: CR group significantly showed the lowest frictional force with all wire tip angulations of 0,4, and 8 degrees. IN significantly showed the highest frictional force (p < 0.001). BR (polyoxymethylene) had significantly less frictional force than SP (polycarbonate) (p < 0.001) and showed no significant difference between metal brackets. Friction was increased as the wire tip angulations were increased, but no notches were observed on any parts of the archwire. Conclusions: According to the results of this study, esthetic brackets are superior or similar to 55 brackets from a frictional point of view.

• The korean journal of orthodontics
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• v.40 no.3
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• pp.156-166
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• 2010

Objective: The surface roughness of orthodontic materials is an essential factor that determines the coefficient of friction and the effectiveness of tooth movement. The aim of this study is to evaluate the surface roughness change of the brackets and wires after experimental sliding quantitatively. Methods: Before and after experimental sliding tests, the surface roughness of stainless steel brackets, ceramic brackets, stainless steel wires, and beta-titanium (TMA) wires were investigated and compared using atomic force microscopy (AFM). Results: After sliding tests, changes in the surface of the wire were greater than changes in the bracket slot surface. The surface roughness of the stainless steel bracket was not significantly increased after sliding test, whereas the roughness of ceramic brackets was decreased. Both the surface roughness of stainless steel and TMA wires were increased after sliding test. More changes were observed on the ceramic bracket than the stainless steel bracket. Conclusions: AFM is a valuable research tool when analyzing the surface roughness of the brackets and wires quantitatively.

• The korean journal of orthodontics
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• v.29 no.1 s.72
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• pp.107-112
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• 1999

As increasing number of adult patients, the esthetic orthodontic appliances are needed. They are tooth-colored or translucent ceramic and resin brackets. Although ceramic and resin bracket have good esthetics, there are some disadvantage such as frictions. Recently, metal-reinforced resin bracket(MRBB) were introduced. The purpose of this study is to find frictional force of MRRB, ceramic bracket and resin brackets. There is few study in frictional force about metal reinforced resin bracket(MRRB). This study used 4 orthodontic wire(.016 S-S, .0l6X.022 S-S, .016 $TMA^{\circledR}$, .0l7X.025 $TMA^{\circledR}$ and 5 brackets(one metal bracket, one ceramic bracket, one resin bracket, two MRRB). The following result is obtained using metal bracket(Ormco.Co., U.S.A), ceramic brackets($Crystalline^{\circledR}$), resin bracket( Clear Medium $Siamase^{\circledR}$). Following conclusions are obtained. 1. Ceramic and resin bracket have significantly more frictional forces than metal reinforced resin bracket and metal bracket. 2. There is no significant difference in frictional force according to the slot types of metal - reinforced resin brackets. 3. There is no significant difference in frictional force between metal reinforced resin bracket and metal bracket. 4.. Frictional force is decreased in S-S wire than TMA wire.

• 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.27 no.2
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• pp.315-326
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• 1997

The purpose of this study was to evaluate the shear bond strength of three kinds of different ceramic brackets with three different bonding adhesives. 5 specimens for each combination were tested for shear bond strength using Instron and for fracture site using SENL And 3 specimens were cross-sectioned for SEM examination of bonding pattern between bracket, resin and enamel surface. The results were as follows 1. The shear bond strength of chemical curing adhesives were higher than that of light curing adhesives. 2. The shear bond strength of Starfire bracket, chemical-bonded type, was lower than that of Transcend bracket, mechanical-bonded type, and Fascination bracket, combined type. 3. Fracture site of each bracket and tooth surface was examined under a light optical stereoscopic microscope, Transcend groups were mainly at the E/R intderface. Fascination groups were mainly at the COMB interface and Starfire groups were mainly at the R/B interface.