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.
Esfandiar Akhavan Niaki; Javad Chalipa; Ahmad Reza Dehpour; M Khalili; Arezoo Ghahari
Abstract
Aim: The appearance of osteoclasts is the first step in orthodontic tooth movement. During orthodontic force application, the periodontal ligament (PDL) undergoes hyalinization. This tissue damage prevents the tooth from moving until the adjacent bone and necrotic tissue are removed by osteoclasts. There ...
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Aim: The appearance of osteoclasts is the first step in orthodontic tooth movement. During orthodontic force application, the periodontal ligament (PDL) undergoes hyalinization. This tissue damage prevents the tooth from moving until the adjacent bone and necrotic tissue are removed by osteoclasts. There is a range of forces that produce the maximum rate of tooth movement. The purpose of this study was to compare the effect of different orthodontic forces on osteoclast numbers.Materials and Methods: Forty rats were randomly divided to 4 experimental groups. Appliance exerted 25gr in light, 40gr in moderate and 60gr in heavy group. There was not any appliance in control group. Animals were sacrified after 14 days and tissue samples were prepared. The mesial and distal surfaces of first upper molar and adjacent alveolar bone were studied. Osteoclast numbers, cementoclast numbers, root length, root resorption, depth and length of resorptive cavities, PDL. width in coronal-middle-apical, apical and coronal inflammation, bone resorption, necrotic bone and tooth movement were evaluated. Mesial and distal surfaces were also compared.Results: In menial osteoclast numbers, depth of resorptive cavities, bone resorption, necrotic bone, PDL width and in distal apical inflammation, bone resorption, necrotic bone and PDL width were significant. Tooth movement was significantly different between all groups. (P<0.05)Conclusion: This data suggest that osteoclasts numbers are increased when force is increased. The magnitude of the orthodontic force is believed to be an important factor, not only for the magnitude of the tooth movement but also for any tissue damage.
