• 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.21 no.3
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• pp.481-493
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• 1991

The purpose of this study was to obtain the norm of the crown shape (tip, torque, in/out) and arch form, and to provide basic data for fabricating straight wire bracket and ideal arch wire for Korean. 100 subjects aged from 17 to 26 (50 females, 50 males) were selected with a normal occlusion. By measuring the size, angulation, inclination, arch width, facial prominance of the teeth and the molar offset, the following results were obtained. 1. Average, standard deviation, minimum, maximum of each measuring item for each teeth were obtained. 2. Intermolar width (${\underline{6}}$ to ${\underline{6}}$) of upper arch before occlusal surface cutting and intermolar width of upper arch (${\underline{6}}$ to ${\underline{6}}$, ${\underline{7}}$ to ${\underline{7}}$) after occlusal surface cutting showed statistical difference. There was no difference between sexes in any other measuring items. 3. Arch form and specification of straight wire bracket for Korean who have normal occlusion was obtained.

• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.731-740
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• 1998

In the previous studies about prescription of preadjusted appliance, occlusal plane was used as a reference plane for crwon angulation (tip) measurement. But this reference plane is not parallel to the line connecting the facial axis points at which the centers of brackets are positioned (Andrews' plane), due to the curve of Spee. Therefore, we developed a new reference plane unaffected by the curve of Sun and more parallel to the Andrews' plane. It is an imaginary line connecting mesial and distal marginal ridges of each posterior tooth, and we named it 'marginal ridge plane'. In this study, crown angulations of posterior teeth of 29 normal occlusion samples were measured and measurements from both reference planes were compared. Crown angulation measurements measured from occlusal plane were different from crown angulation measurements from marginal ridge plane in the upper and lower 2nd molars (p<0.01), md 1st premolars (p<0.05). These results were analyzed as the crown angulation measurements from occlusal plane were affected by the curve of Spee. Crown angulations should be varied according to the amount of curve of Spee to maintain the continuity of marginal ridges. To solve this problem, determining bracket angulation as the bracket slot is parallel to the marginal ridge plane of each posterior teeth is recommended.