|
KMID : 0361920010310030311
|
|
Korean Journal of Orthodontics
2001 Volume.31 No. 3 p.311 ~ p.323
|
|
|
A FEM comparison study abut the force, displacement and initial stress distribution on the maxillary first molars by the application of Asy mmetric Head-Gears with the different traction forces
|
|
Cha Kyung-Suk
|
|
|
Abstract
|
|
|
One of the various mechanics used to treat unilateral Class II malocclusion is head gear with asymmetric face bow. We made the finite element models of unilateral Class II maxillary dental arch and power arm asymmetric face bow. We designed this experiment to observe stress distribution of periodontal ligament, reaction force, and displacement and to understand force system, so to predict the therapeutic effect.
On the basis of computerized tomograph of maxillary dental arch of 25 years old male with normal occlusion without exxaction and orthodontic treatment history, we made finite element models of maxillary dental arch and periodontal ligament. Then we modified that model to unilateral maxillary Class II malocclusion model of which maxillary left molar displaced mesially. Also, We made finite element model of asymmetric face bow of which right outer bow shorter than left by 25mm(RMO Penta-FormTM / Medium size, 0.045 inch iner bow, 0.072 inch outer bow). After that, retraction force of 250g, 300g, 350g were applied to maxillary first molar.
We concluded as follow.
1. The Net force that both maxillary first molars were received increased as the retraction force increased. Mesially positioned tooth received more force than normally positioned tooth. But, both tooth were received distal force, so distal movement occured.
2. Both tooth received buccal lateral force. In analysis of force element as the retraction force were increased, force of X-axis at mesially positioned tooth decreased, and force of X-axis at normally positioned tooth increased so lateral force component moved to the side received less force from more force.
3. There were rotation, tipping with distal movement in maxillary first molar. As retraction force were increased, rotation and tipping also increased. More tipping and rotation occured at the side received more force, that is, mesially positioned toothy. Though it is small change, displacement of same pattern occur in normally positioned tooth
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
 
|
|
|
Listed journal information
|
|
  
|
|