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KMID : 0361919930230030375
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Korean Journal of Orthodontics
1993 Volume.23 No. 3 p.375 ~ p.390
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Experimental sutdy of the vertical location of the centers of resistance for maxillary anterior teeth during retraction using the laser reflection technique
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Abstract
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The delivery of optimal orthodontic treatment is greatly influenced by a clinician's ability to predict and control tooth movement achieved by applying known force systems to the dentition. It is important to determine the location of the center
of
resistance of a tooth or group of teeth to better understand the nature of their displacement characteristics under the various force levels.
The purpose of this study was to define the location of the centers of resistance of various units of the upper anterior segment for lingually directed 100gm and 200gm force in a dry human skull. The units investigated were compose of four
incisors
and
six anterior teeth. In addition, the effect of change in force magnitude on the location of the center of resistance of these units was investigated. The laser reilection technique was used to measure the initial displacements of the consolidated
teeth
under loading.
@ES The results were as follows:
@EN 1. The instantaneous center of resistance for the four anterior teeth was located vertically between level 4 and level 5-that is. At 37.4% apical to the cememtoenamel junction level.
2. The instantaneous center of resistance for the six anterior teeth was located vertically just beneath level -5-that is, at 50.3% apical to the cementoenamel junction level.
3. Increasing force levels had little effect on the location of the center of resistance of a given unit.
4. The location of the instantaneous center of resistance shitted apically as the number of dental units consolidated increased.
KOREA J ORTHOD 1993 ; 23(3) : 375-389.
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