Biomechanics
Sayyed Muhammad Ali; Javed Sodawala; Shaheen Hamdani; Sumit Gandhi; Harsha Malhotra; Gaurav Agrawal
Abstract
Aim: The purpose of this study was to compare labial and lingual forces of the rate of canine retraction and three dimensional control of the molar and canine using sliding mechanics.Methods: Ten patients with Angle’s class I malocclusion with bimaxillary protrusion referred for first premolar ...
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Aim: The purpose of this study was to compare labial and lingual forces of the rate of canine retraction and three dimensional control of the molar and canine using sliding mechanics.Methods: Ten patients with Angle’s class I malocclusion with bimaxillary protrusion referred for first premolar extraction enrolled in this split mouth study. Forty canines were placed into four groups according to the arch and type of force: UB (upper canine–labial force), LB (lower canine–labial force), UL (upper canine–lingual force), and LL (lower canine–lingual force). The rate of retraction of the canine, molar and canine rotation, molar and canine angulation, and molar anchorage loss in the sagittal and vertical plane was assessed using study models and orthopantomographs (OPG). The paired and unpaired t tests were used for intra and inter group comparison. The significance level was 0.05.Results: The rate of canine retraction was significantly faster for labial forces than lingual forces using sliding mechanics (P<0.001). However, significantly greater amount of molar rotation was observed using lingual forces (P<0.001). There was no significant difference regarding canine rotation using labial forces (P<0.05). The molar anchorage loss in the sagittal plane was significantly lesser using lingual forces (P<0.001).Conclusion: Canine retraction was faster when labial forces were applied using sliding mechanics whereas 3D-molar control was better when lingual forces were applied, which is advantageous for critical anchorage cases.
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.
