Valentin Javier García1, Rubén López-Cancelos2, Antonio Riveiro3, Rafael Comesaña2, Josep Maria Ustrell I Torrent2, Khaled Kasem4, Aida Badaoui2, Mª Cristina Manzanares-Céspedes5, Patricia Carvalho-Lobato5. 1. Orthodontics Unit 5305, Odontostomatology Department, HUBc, University of Barcelona, Planta 2, Pavelló de Govern, C/FeixaLlarga SN, L'Hospitalet de Llobregat, 08907, Barcelona, Spain. valentingarcia2@gmail.com. 2. Department of Materials Engineering, Applied Mechanics and Construction, University of Vigo, Lagoas-Marcosende, 36310, Vigo, Spain. 3. Applied Physics Department, Applied Physics Unit, EEI, University of Vigo, Lagoas-Marcosende, 36310, Vigo, Spain. 4. Orthodontics Unit 5305, Odontostomatology Department, HUBc, University of Barcelona, Planta 2, Pavelló de Govern, C/FeixaLlarga SN, L'Hospitalet de Llobregat, 08907, Barcelona, Spain. 5. Human Anatomy and Embryology Unit 5304, HUBc, University of Barcelona, Pavelló de Govern, C/FeixaLlarga SN, L'Hospitalet de Llobregat, 08907, Barcelona, Spain.
Abstract
OBJECTIVES: Aim of this study was to develop a finite element model of the forces that patients with rapid maxillary expansion bear and to validate it by a mechanical test. METHODS: Computer-aided design models of the metallic screw and polymeric splint were modelled and discretized. Two forces were generated and considered independently: F1 at the temporary molar (2.5 N) and F2 at the permanent molar (2.5 N). The results of the finite element analysis were used to define the strain values which the anterior and posterior arms of the rapid maxillary expansion appliance bore as a linear function of F1-F2 by calculating the strain-force coefficient δ ij . Two strain gauge rosettes were attached to an appliance which was placed in an XY motorized stage to reproduce the same forces used in the finite element analysis. Once the system was validated, the matrix was inverted to determine forces F1 and F2 that a group of 40 patients underwent (median age 8.33 years, standard deviation 1.86 years) for 75 days, using their strain values. The parents of the patients activated a quarter turn (0.20 mm) twice a day until 50% transversal overcorrection was achieved. RESULTS: Finite element analysis showed that the effects of the forces on stress at the location of the arms were notably different. There was a satisfactory correlation between finite element analysis predictions and in vitro values. Dissipation of F1 and F2 in patients was predicted to be 62.5 and 80%, respectively, after 75 days of retention. CONCLUSION: These results back the finite element analysis model for force prediction.
OBJECTIVES: Aim of this study was to develop a finite element model of the forces that patients with rapid maxillary expansion bear and to validate it by a mechanical test. METHODS: Computer-aided design models of the metallic screw and polymeric splint were modelled and discretized. Two forces were generated and considered independently: F1 at the temporary molar (2.5 N) and F2 at the permanent molar (2.5 N). The results of the finite element analysis were used to define the strain values which the anterior and posterior arms of the rapid maxillary expansion appliance bore as a linear function of F1-F2 by calculating the strain-force coefficient δ ij . Two strain gauge rosettes were attached to an appliance which was placed in an XY motorized stage to reproduce the same forces used in the finite element analysis. Once the system was validated, the matrix was inverted to determine forces F1 and F2 that a group of 40 patients underwent (median age 8.33 years, standard deviation 1.86 years) for 75 days, using their strain values. The parents of the patients activated a quarter turn (0.20 mm) twice a day until 50% transversal overcorrection was achieved. RESULTS: Finite element analysis showed that the effects of the forces on stress at the location of the arms were notably different. There was a satisfactory correlation between finite element analysis predictions and in vitro values. Dissipation of F1 and F2 in patients was predicted to be 62.5 and 80%, respectively, after 75 days of retention. CONCLUSION: These results back the finite element analysis model for force prediction.
Entities:
Keywords:
Finite element analysis; Forces; Rapid maxillary expansion; Strain gauges
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