Stress and Displacement Pattern in the Maxilla and the Mandible with Reverse Twin Block: A Finite Element Analysis
Journal Title: Journal of Clinical and Diagnostic Research - Year 2018, Vol 12, Issue 7
Abstract
Introduction: Class III malocclusion exists when the mandibular molar occludes mesial to the maxillary molar as a result of a skeletal discrepancy i.e., normal maxilla and protruded mandible, retruded maxilla and a normal mandible or a retruded maxilla and a protruded mandible, concomitant with or without a dental discrepancy, or due to the functional shift of the mandible. Orthopaedic and functional appliances like chin cup, Functional Regulator 3 (FR3), Class III activator, reverse twin block etc., can be used to treat Class III malocclusion. Reverse twin block is a patient friendly appliance, presenting acceptable clinical results. Stresses are the key to remodelling of the alveolar and craniofacial bones incident to functional and orthopaedic forces, which can be elucidated via Finite Element Analysis (FEA). Literature lacks studies pertaining to biomechanical evidence on the functional appliance effect in Class III malocclusion. Aim: To evaluate the patterns of stress distribution and displacement in the maxilla and the mandible with the reverse twin block appliance, in four groups with combinations of bite force of 107 N and without bite force, along with passive tension of 1.27 N and 1.47 N for 2 mm and 4 mm interincisal clearance respectively, through FEA. Materials and Methods: A three dimensional finite element model was developed from the Cone Beam Computed Tomography (CBCT) images of a patient with Class III malocclusion using Hypermesh 13.0 software. The model simulated forces of reverse twin block appliance with 2 mm and 4 mm interincisal clearance with and without maximum bite force of 107 N. Stress distribution and displacement in the region of glenoid fossa, maxillary tuberosity, Anterior Nasal Spine (ANS), neck of the condyle and gonial region was studied. Results: Maximum stresses were observed in the glenoid fossa and the neck of the condyle. Stress generation was subsequently more with 4 mm interincisal clearance group. The displacement resulting from reverse twin block was mainly dentoalveolar. Maxillary incisors displaced more than the mandibular incisors. The mandible displaced more in the forward and downward direction. Conclusion: The treatment outcomes with reverse twin block appliance previously assessed by means of cephalometric studies were validated with insight of stresses induced at different regions of the maxilla and the mandible via the finite element methodology. The forces exerted by this appliance directed the stresses more towards the dentoalveolar region. Stresses were more profound when the passive tension was concurrent with the bite force.
Authors and Affiliations
Adeeba Khanum, Sunil Kumar, Silju Mathew, Prashantha Govinakovi Shivamurty, Vinod , Pattabiraman, Madhavi Naidu
Keywords
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- EP ID EP526069
- DOI 10.7860/JCDR/2018/35426.11775
- Views 100
- Downloads 0
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