J Korean Assoc Oral Maxillofac Surg 2017; 43(2): 77~82
Mechanical evaluation of the use of conventional and locking miniplate/ screw systems used in sagittal split ramus osteotomy
Zarina Tatia Barbosa Vieira Santos1, Douglas Rangel Goulart1, Eder Alberto Sigua-Rodriguez1, Leandro Pozzer1, Sergio Olate2,3, José Ricardo Albergaria-Barbosa1
1Division of Oral and Maxillofacial Surgery, State University of Campinas, Campinas, Brazil,
2Division of Oral and Maxillofacial Surgery & CEMYQ, Universidad de La Frontera,
3Center for Biomedical Research, Universidad Autónoma de Chile, Temuco, Chile
Sergio Olate
Division of Oral and Maxillofacial Surgery, Universidad de La Frontera, Claro Solar 115, Of. 414-A, Temuco 4780000, Chile
TEL: +56-45-2325000
FAX: +56-45-2592822
E-mail: sergio.olate@ufrontera.cl
Received August 16, 2016; Revised November 6, 2016; Accepted November 30, 2016.; Published online April 30, 2017.
© Korean Association of Oral and Maxillofacial Surgeons. All rights reserved.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Objectives: The aim of this study was to compare the mechanical resistance of four different osteosyntheses modeled in two different sagittal split ramus osteotomy (SSRO) designs and to determine the linear loading in a universal testing machine.
Materials and Methods: An in vitro experiment was conducted with 40 polyurethane hemimandibles. The samples were divided into two groups based on osteotomy design; Group I, right angles between osteotomies and Group II, no right angles between osteotomies. In each group, the hemimandibles were distributed into four subgroups according to the osteosynthesis method, using one 4-hole 2.0 mm conventional or locking plate, with or without one bicortical screw with a length of 12.0 mm (hybrid technique). Each subgroup contained five samples and was subjected to a linear loading test in a universal testing machine.
Results: The peak load and peak displacement were compared for statistical significance using PASW Statistics 18.0 (IBM Co., USA). In general, there was no difference between the peak load and peak displacement related to osteotomy design. However, when the subgroups were compared, the osteotomy without right angles offered higher mechanical resistance when one conventional or locking 2.0 mm plate was used. One locking plate with one bicortical screw showed higher mechanical resistance (162.72±42.55 N), and these results were statistically significantly compared to one conventional plate with monocortical screws (P=0.016) and one locking plate with monocortical screws (P=0.012). The difference in peak displacement was not statistically significant based on osteotomy design or internal fixation system configuration.
Conclusion: The placement of one bicortical screw in the distal region promoted better stabilization of SSRO. The osteotomy design did not influence the mechanical behavior of SSRO when the hybrid technique was applied.
Keywords: Sagittal split ramus osteotomy, Jaw fixation techniques, Orthognathic surgery

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31 October 2017
Vol. 43
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