The purpose of this study was to analize the initial stress distribution around apex and the alveolar bone of the upper anterior teeth when applying intrusive force by the use of utility archwire, Burstone 3-piece intrusion archwire, and "J" hook headgear which is usually used in clinical practice.
By the use of the polarization plate, initial stresses were analized when 80g and 150g force applied.
The results were as follows.
1. With the utility archwire, moderate levels of stress were evenly distributed on the apical areas of the anterior teeth and concentrated on the apical areas of the first molars.
2. With the Burstone´s 3-piece intrusion archwire, moderate levels of stress were evenly distributed on the apical areas of the anterior and posterior teeth.
3. With the "J" hook headgear, severe levels of stress were widely distributed on, the alveolar- bone and apical areas of the upper anterior teeth, and concentrated on the apical area between the central and the lateral incisors.
Especially. weak levels of stress appeared along the periodontal ligament space of all teeth.
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