Allahyar Geramy; Seyed Amir Reza Fatahi Meybodi; Amir Hooman Sadr Haghighi
Abstract
Aim: To analysis the effect of unilateral shortening (Asymmetric Length, AL type) vs. expansion of head-gear outer-bow (Asymmetric Expansion, AE type) in delivering unilateral distal force.Methods: In 36 situations, composed or different outer-bow shortening, expansion and different neck contour and ...
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Aim: To analysis the effect of unilateral shortening (Asymmetric Length, AL type) vs. expansion of head-gear outer-bow (Asymmetric Expansion, AE type) in delivering unilateral distal force.Methods: In 36 situations, composed or different outer-bow shortening, expansion and different neck contour and position, the resultant distal force was analyzed. Applying an analysis described by Haack and Wienstein, the ratio by which the resultant distal force was divided between 2 terminal molars was calculated.Results: In AL type head-gear a greater portion of force was delivered to contra-lateral terminal while in AE type headgear the ratio of force delivery between two molars could not be higher than 1.04 due to geometrical limitations.Conclusion: AL type head-gear is a predictable and effective way for asymmetric distal force delivery. The greater force will be received by the contra-lateral terminal to the shorter arm of the outer-bow. AE type is not suggested for distal force delivery due to its geometric limitation and relative ineffectiveness.
Allahyar Geramy; Amir Hooman Sadr haghighi; Seyed Amir Reza Fatahi Meybodi; Hasan Salehi
Abstract
Aim: Canine retraction is an important part of orthodontic treatments and should be coincided with preservation of posterior anchorage, The strain energy input of different appliance designs in teeth PDL is assessed.Materials and methods: Eight 3D finite element (FE) models of upper right maxillary molars ...
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Aim: Canine retraction is an important part of orthodontic treatments and should be coincided with preservation of posterior anchorage, The strain energy input of different appliance designs in teeth PDL is assessed.Materials and methods: Eight 3D finite element (FE) models of upper right maxillary molars and second premolar were designed. The models contained teeth, their PDL, and bone with their attachments. Combinations of wire cross scetion(round and rectangular), force application on the first or second molar, including or excluding the second molar, and adding the second molar to the system via ligature wire is considered in different models. The strain energy input to the PDL of different teeth was evaluated.Results: Engagement of all teeth, force application to the second molar resulted in 0.00017129 mJ and shifting toward applying force to the first molar resulted in 0.00017398 mJ. When the second molar was free from wire but laced; this energy finding was 0.00014499 mJ which increase to 0.0003991 mJ when the second molar was really out of the system. Findings for the rectangular wire were 0.00000084, 0.000001148, 0,0001026, and 0.0002929 respectively.Conclusion: Rotation prevention of the second molar is the key point in using its anchorage value.
Allahyar Geramy; Amir hooman Sadr Haghighi; Saeede Mokhtari Khoee
Abstract
Aim: Orthodontic treatment outcomes are combination of advantages and disadvantage. The force implied during treatment could affect dental pulp status. Amount of changes in pulp complex depend on the types of tooth movements and whether the apex is open or not. The aim of this study is to compare the ...
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Aim: Orthodontic treatment outcomes are combination of advantages and disadvantage. The force implied during treatment could affect dental pulp status. Amount of changes in pulp complex depend on the types of tooth movements and whether the apex is open or not. The aim of this study is to compare the effects of different orthodontic tooth movements in two kinds of open and normal apices by 3D Finite element analysis.
Materials and Methods: Two three-dimensional Finite element models of an upper central incisor were modeled based on average dimensions. The models contained cortical and spongy bone, uniform thickness PDL of 0.25 mm and an upper central incisor. The differences between the models was the apex development which was complete in the first model and open in the second one in Solid- works 2006 and transferred to ANSYS Workbench Ver. 11.0. Different force systems to produce tipping, bodily and intrusion were applied in the tooth crown. The Von Mises stress was assessed along two defined paths.
Results: Maximum amount of the stress along the long axis of pulp belonged to open apex by tipping movement then intrusion with normal apex and finally bodily movement in open apex samples. In evaluation as regard of stress along apical third of PDL the highest stress created by intrusion in normal apex group.
Conclusion: In open apex, tipping and bodily movement could induce much more stress and in normal apex the concern of root resorption by intrusion was more than other types of tooth movements.
