Evaluation of Stresses and Forces in Selected I-Bars Using the Finite Element Method |
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| Authors: | Preeti R. Naik BDS MS Manville G. Duncanson Jr. DDS PhD Donald L. Mitchell DDS MS Frank J. Wiebelt DDS Dean L. Johnson DDS MEd Joydeep Ghosh BDS MS |
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| Affiliation: | Research Fellow, Department of Removable Prosthodontics University of Oklahoma, College of Dentistry, 1001 SL Young Blvd, Oklahoma City, OK 73190.;Professor and Chair, Department of Dental Materials, University of Oklahoma, College of Dentistry, 1001 SL Young Blvd, Oklahoma City, OK 73190.;Associate Professor and Chair, Department of Implantology, University of Oklahoma, College of Dentistry, 1001 SL Young Blvd, Oklahoma City, OK 73190.;Associate Professor and Chair, Department of Removable Prosthodontics, University of Oklahoma, College of Dentistry, 1001 SL Young Blvd, Oklahoma City, OK 73190.;Professor Emeritus and Former Director of Graduate Prosthodontics, University of Oklahoma, College of Dentistry, 1001 SL Young Blvd, Oklahoma City, OK 73190.;Assistant Professor, Department of Orthodontics, University of Oklahoma, College of Dentistry, 1001 SL Young Blvd, Oklahoma City, OK 73190. |
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| Abstract: | ![]()
Purpose Three-dimensional models of half-round, tapered and full-round, untapered I-bar clasps of varying configurations and material properties were constructed. The purpose of this study was to examine the stresses and reaction forces produced within each model upon deflection to 0.01 in (0.254 mm), 0.02 in (0.508 mm), and 0.03 in (0.762 mm) at 1 mm from the tip using the finite element method. Materials and Methods Three-dimensional computer models of half-round and full-round clasps were constructed using solid eight-node brick elements. The half-round, tapered I-bar clasp model was 2.4 and 1.4 mm in diameter at the base and tip, respectively. The full-round, tapered I-bar clasp model was 1 mm in diameter. Three design groups were created for each clasp form. Group A had 25% of the total length in the straight anchor end of the I-bar clasp, B had 35%, and C had 50%. All models were 31 mm in length and had a radius of curvature of 5 mm. Different material properties were incorporated into the models. Each model was deflected at a point 1 mm from the tip to 0.01 in (0.254 mm), 0.02 in (0.508 mm), and 0.03 in (0.762 mm). Results The stresses and forces produced as a result of the deflection applied to each clasp were viewed and displayed graphically. The maximum von Mises stresses in megapascals and the reaction force in newtons (N) were recorded. Stresses varied in each clasp in the range of 0 to 154.3 MPa for the half-round, tapered I-bar clasp models, and 0 to 100.9 MPa for the full-round I-bar clasp models at 0.01-in deflection. Reaction force measured near the tip of the clasp models was between 1.60 N and 6.31 N for the half-round, and between 0.22 N to 2.13 N for the full-round I-bar clasp models. For all clasps studied, as the deflection increased, the location of stress within each group remained the same regardless of the material properties; however, the stress and force values increased linearly. Conclusions The location of maximum stress varied with the length of the anchor portion of the clasps studied. Maximum stresses were located on the flat side of the half-round, tapered I-bar clasp model. |
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| Keywords: | finite element analysis half-round tapered I-bar full-round untapered I-bar |
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