Parham Pedram; Hannane Ghadirian; Sepideh Arab
Abstract
Background: Splinting anterior teeth is a way to fix them after orthodontics treatments. Occlusal trauma from functional or parafunctional forces can cause stress increase and movements of teeth especially while having bone loss.
Methods: Six anterior teeth with different bone levels were designed in ...
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Background: Splinting anterior teeth is a way to fix them after orthodontics treatments. Occlusal trauma from functional or parafunctional forces can cause stress increase and movements of teeth especially while having bone loss.
Methods: Six anterior teeth with different bone levels were designed in SolidWorks (2010), the models were then transferred to ANSYS Workbench 12.1. The models were loaded with 187 N force on the incisal edges of two incisors. Results: Stress on canine was 0.45 MPa in normal bone height and increased to 0.60 MPa in five millimeters of anterior teeth bone loss. Labial displacement was less in normal alveolar bone height while it was increased in all those teeth with five millimeter of bone loss.
Conclusions: Splinting distribute the forces between teeth and the stress production on canine increase while it splinted with low level bone incisors. Anterior teeth also showed tipping movements in reply to increased forces.
Jean Marc Retrouvey; Allahyar Geramy
Abstract
Background: Occlusal loads are always present though not widely considered in orthodontic treatments. Applied force systems are analyzed in detail and taught but their interaction with occlusal force is oftentimes ignored. Numeric evaluation of this combination by finite element method is the main goal ...
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Background: Occlusal loads are always present though not widely considered in orthodontic treatments. Applied force systems are analyzed in detail and taught but their interaction with occlusal force is oftentimes ignored. Numeric evaluation of this combination by finite element method is the main goal of this research.
Objectives: The present study has implemented FEA to investigate the effect of orthodontic force application on the tooth-periodontium-alveolar bone system. Materials and Methods: A 3D model of a lower premolar was designed. The model contained cortical and spongy bone, PDL, and tooth. A 1.73 N force decomposed to 1 N in each plane axis was applied as a random levelling and aligning force to assess the von Mises stress produced at the mesial aspect of the PDL from cervical down to the apical area. At the second phase a 200-Newton intruding force vector was applied simulating the occlusal force. The effects of the combination force system were evaluated in the same area of the PDL. Results: The maximum finding of von Mises for both stages were in found in the cervical area. This was almost 0.267 MPa for the first stage and 2.27 MPa for the second stage.
Conclusions: Our findings show that the co-existence of heavy occlusal forces due to clenching or bruxism in our tooth-periodontium-orthodontic force system has a significant influence on the magnitude and location of the high stress areas.
Hasan Salehi; Sepide Arab
Abstract
Background: Alignment of the teeth as the first stage of comprehensive orthodontic treatment has widely been addressed. Several methods such as using super elastic arch wires, multi-strand wires and incorporation of various loops into the round stainless steel wires have been suggested in this stage.
Objectives: ...
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Background: Alignment of the teeth as the first stage of comprehensive orthodontic treatment has widely been addressed. Several methods such as using super elastic arch wires, multi-strand wires and incorporation of various loops into the round stainless steel wires have been suggested in this stage.
Objectives: The aim of this study was to investigate and compare the horizontal forces produced by six various loop designs in different amounts of activation using the finite element method. Materials and Methods: The Finite Element Model (FEM) was used to design and compare the horizontal forces of round 0.014 inches stainless steel vertical open loop, vertical closed loop, vertical helical open loop, vertical helical closed loop, plain vertical loop and the squash loop. The forces were measured at 0.1, 0.4, 0.8 and 1mm activations. Results: For all activations, vertical open loop had the highest horizontal force; while vertical helical closed loop showed the lowest force.
Conclusions: The design of vertical loops influences the horizontal force in all activations, immensely.
Allahyar Geramy; Tahura Etezadi; Ahmad Reza Shamshiri; Mohammad Javad Kharazifard
Abstract
Introduction: An appropriate force system is a perquisite of desirable and predictable tooth movements during orthodontic treatment. Complete knowledge about the generated forces and moments by loops is essential to choose the best one for every situation.The aim of this study was to establish a mathematical ...
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Introduction: An appropriate force system is a perquisite of desirable and predictable tooth movements during orthodontic treatment. Complete knowledge about the generated forces and moments by loops is essential to choose the best one for every situation.The aim of this study was to establish a mathematical equation to bring about a relationship between the L-loop height, width, activation and the produced force.Materials and methods: Six 3D finite element models were designed for L-loop without preactivation bends. Loops were designed with different widths (w) and heights (h). The cross section of wire was 0.016”× 0.022”. The distal end of each model was activated 1 mm in 0.1 mm intervals. The force produced by activation in a 0.1 millimeter increment was recorded. Results: Force findings were different according to the loop parameters defined. The produced force varies from 0.106 to 0.228 N for a 0.1 millimeter of activation and increased from 1.07 to 2.27 N in 1.0 mm of activation.Conclusion: The magnitude of force by L-loop can be estimated through adjustment of vertical part and activation as Increments of activation increased the delivered force while Increasing L-loop height decreased the generated force.
Allahyar Geramy; Tahoora Etezadi
Abstract
Desirable tooth movements need optimal force systems. Loops are employed to move teeth properly. L-loop is used frequently due to its ease of fabrication. The aim of this study is to assess the expected forces and moments when a definite length of wire is bent to form L-loop. In other words, the effect ...
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Desirable tooth movements need optimal force systems. Loops are employed to move teeth properly. L-loop is used frequently due to its ease of fabrication. The aim of this study is to assess the expected forces and moments when a definite length of wire is bent to form L-loop. In other words, the effect of loop height and width on the produced force and moment is evaluated by the finite element method (FEM). Materials and methods: Six 3D finite element models were designed of an L-loop without pre-activation bends keeping the total lengths of wire equal to 24.34+/- 0.5 mm. The cross section of wire was 0.016”× 0.022”. The force produced by activation in a 0.1 millimeter increment was recorded. Results: In model L1, the findings start with 0.086 N in 0.1 mm of activation and increased to 0.88 N in 1mm of loop opening. The pattern of findings was almost the same for other loop designs (L2 through L6) with an increase in findings. M/F ratios were almost constant in a loop design along its activation starting with 3 in L1 and reaching about 1.9-2 in L6. Conclusions: Moment to force ratios were almost constant in a loop design along its activation. increasing width and decreasing height with almost the same length of loop wire can increase force and therefor reduce M/F ratio.
Azita Tehranchi; Hossein Behnia; Majid Heidarpour; Bahman Toutiaee; Mohammad Javad Khosropour
Abstract
Aim: Analyzing the changes made during distraction osteogenesis (DO) in asymmetric mandibles.Materials and methods: This study was performed on a three dimensional model of a desiccated mandible, based on a finite element method. The distraction devices were placed with an angle of 90, 60 or 30 degrees ...
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Aim: Analyzing the changes made during distraction osteogenesis (DO) in asymmetric mandibles.Materials and methods: This study was performed on a three dimensional model of a desiccated mandible, based on a finite element method. The distraction devices were placed with an angle of 90, 60 or 30 degrees to the oblique surgical cut. The directions of the pins were such that the 30 and 60 degree pins were placed in a counterclockwise direction relative to the perpendicular pin. The distractors were opened for 15 and 30 mm. The amount and direction of movement of proximal and distal segments and the displacement of pogonion were evaluated in all three planes of space.
Results: In the distal segment, the maximum change in pogonion was seen in 30 degree angle. In the proximal segment, if the distraction device was used with 90 degree angle, the condylar process rotated in the clockwise rotation. In 30 degree angle, this process rotated in a counterclockwise direction and the minimum rotation was seen in 60 degree angle.Conclusion: If gonial angle is to be augmented in a downward direction maximally, the angle of distraction device to the surgical cut is critically important (that is, it should be perpendicular to surgical cut). By use of perpendicular mode, ramus slops more posteriorly. It is better to use the distraction pin with a thirty degree angle if the ramus needs to be uprighted. The oblique surgical cut, irrespective of the distraction pin angle, increases the anterior facial height.
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.
Allahyar Geramy
Abstract
Aim: Introduction of new bracket designs in market and use with a range of inciso-apical dimension and base thickness arises a question in mind as "Is it necessary to standardize various bracket bases from torque delivery efficiency?"
Materials and Methods: Two bracket bases of different incio-apical ...
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Aim: Introduction of new bracket designs in market and use with a range of inciso-apical dimension and base thickness arises a question in mind as "Is it necessary to standardize various bracket bases from torque delivery efficiency?"
Materials and Methods: Two bracket bases of different incio-apical dimension (3 and 6 mm.) and also two different base thicknesses (1.6 and 3.5 mm.) were modeled and moments were applied. All displacements along a defined incio-apical path were monitored to be evaluated.
Results and Conclusion: No difference was found between the displacements along the defined path in each phase of study. In this way, it was concluded that torque delivery of different brackets is not related to their base size (inciso-apical) and dimenson which is in complete agreement and confirmation of the principle of free vectors. (IJO 2006; 1: 71 - 74)
Allahyar Geramy
Abstract
Aim: Being aware of the active and reactive forces and moments in an applied force system helps minimizing side effects and informing patients of future happenings. Wire bends are still used in clinical orthodontics in different ways.
Material and Methods: Three models were designed in SolidWorks 2006. ...
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Aim: Being aware of the active and reactive forces and moments in an applied force system helps minimizing side effects and informing patients of future happenings. Wire bends are still used in clinical orthodontics in different ways.
Material and Methods: Three models were designed in SolidWorks 2006. A step bend of 0.5 mm, a model of two central incisors with their supporting structures, and two blocks with a space and a wire with a combination of two step bends to modify the tooth angulation. Then the models were transferred to ANSYS Workbench Ver. 11.0 for calculations. Different positions of a step bend and the force systems produced by them were assessed.
Results: A gradual decrease of force produced by the step bend between 316 and 308 grams was shown to exist in central step bend position and the extreme one. The moment followed almost the same pattern starting from 15.125 N.mm in center bend position to 14.135 N.mm in its extreme position. In combined step bend model, extrusive/ lingualized movment in one side and intrusive/ labialized in the other side and tipping of the crowns in one and the apices to other side was also shown.
Conclusion: Step bend is not sensitive to its position and almost the same force system is produced in different bend positions (IJO 2006;1: 194-7).
Allahyar Geramy
Abstract
Aim: Several bracket characteristics are now in market. Preformed archwires are used without frequent need to add bends. V-bends are used in many situations. This bend as a basic maneuver is assessed thoroughly in this study.Materials and Methods: Finite Element Method (FEM) was selected to analyze the ...
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Aim: Several bracket characteristics are now in market. Preformed archwires are used without frequent need to add bends. V-bends are used in many situations. This bend as a basic maneuver is assessed thoroughly in this study.Materials and Methods: Finite Element Method (FEM) was selected to analyze the situation. A 3D model of two maxillary central incisors with their supporting structures and an archwire were modeled. A V-bend in different positions relative to the teeth was defined. Forces produced were monitored.Results: Center V-bend (a/L=1/2) produced two moments in opposite direction. Moving towards one tooth added vertical forces in opposite direction. At a/L ˜˷115, intrusive movement was noticed; while signs of intrusion and change in angulation was detected at 1/10< a/L<1/5. When a/L reached 0.42/6.408 same direction of moments were shown.Conclusion: V-bend force system is quite sensitive to its position.
