Eder Alberto Sigua-Rodriguez1, Ricardo Armini Caldas2, Douglas Rangel Goulart3, Paulo Hemerson de Moraes4, Sergio Olate5, Valentim Adelino Ricardo Barão2, Jose Ricardo de Albergaria-Barbosa3. 1. Piracicaba Dental School, Oral and Maxillofacial Surgery (Department of Oral Diagnosis), (Head: Jose Ricardo de Albergaria-Barbosa), State University of Campinas e UNICAMP, P.O. Box 52, Piracicaba, Sao Paulo, 13414-903, Brazil; Centro de Investigaciones del Colegio Odontológico (CICO), Institución Universitaria Colegios de Colombia, Bogotá, Colombia. Electronic address: edersiguaodont@gmail.com. 2. Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil. 3. Piracicaba Dental School, Oral and Maxillofacial Surgery (Department of Oral Diagnosis), (Head: Jose Ricardo de Albergaria-Barbosa), State University of Campinas e UNICAMP, P.O. Box 52, Piracicaba, Sao Paulo, 13414-903, Brazil. 4. University of Porto, FEUP, Faculty of Engineering, Portugal. 5. Division of Oral and Maxillofacial Surgery, Universidad de La Frontera, Brazil; Center for Biomedical Research, Universidad Autónoma de Chile, Temuco, Chile.
Abstract
PURPOSE: To evaluate three rigid, stable fixation methods for sagittal split ramus osteotomy (SSRO), using finite element analysis. The hypothesis is that a customized miniplate presents better stress concentration and distribution. MATERIALS AND METHODS: A 3D model of a hemimandible was created, and a 10-mm-advancement SSRO was simulated and fixed as follows: 3-DCP group - one custom miniplate fixed by eight screws; 4-H2P group - two miniplates of four holes each, fixed by eight screws; and 6-H2P group - two miniplates of six holes each fixed by 12 screws. After a vertical loading of 100 N, the values for von Mises stress, modified von Mises stress, and maximum and minimum principal stresses were measured. RESULTS: The area of maximum principal stress was similar for the three groups - located in the upper miniplate, in the screw near the proximal segment osteotomy. The maximum von Mises stresses were 1580.4 MPa, 1005 MPa, and 977.56 MPa for the 3DCP, 4-H2P, and 6-H2P groups, respectively, showing an allowable displacement of 2.57 mm, 1.62 mm, and 1.52 mm for the 3DCP, 4-H2P, and 6-H2P groups, respectively. CONCLUSION: The customized miniplate did not present better stress distribution than two commonly used types of fixation. Fixation with two straight miniplates, either with four or six holes, offers adequate resistance for 10 mm linear advancements.
PURPOSE: To evaluate three rigid, stable fixation methods for sagittal split ramus osteotomy (SSRO), using finite element analysis. The hypothesis is that a customized miniplate presents better stress concentration and distribution. MATERIALS AND METHODS: A 3D model of a hemimandible was created, and a 10-mm-advancement SSRO was simulated and fixed as follows: 3-DCP group - one custom miniplate fixed by eight screws; 4-H2P group - two miniplates of four holes each, fixed by eight screws; and 6-H2P group - two miniplates of six holes each fixed by 12 screws. After a vertical loading of 100 N, the values for von Mises stress, modified von Mises stress, and maximum and minimum principal stresses were measured. RESULTS: The area of maximum principal stress was similar for the three groups - located in the upper miniplate, in the screw near the proximal segment osteotomy. The maximum von Mises stresses were 1580.4 MPa, 1005 MPa, and 977.56 MPa for the 3DCP, 4-H2P, and 6-H2P groups, respectively, showing an allowable displacement of 2.57 mm, 1.62 mm, and 1.52 mm for the 3DCP, 4-H2P, and 6-H2P groups, respectively. CONCLUSION: The customized miniplate did not present better stress distribution than two commonly used types of fixation. Fixation with two straight miniplates, either with four or six holes, offers adequate resistance for 10 mm linear advancements.