title: An in vitro comparison between two different designs of sagittal split ramus osteotomy.
abstract: OBJECTIVE
  To evaluate the influence of the type of osteotomy in the inferior aspect of the mandible on the mechanical performance.
  
  
  METHODS
  The study was performed on 20 polyurethane hemimandibles. A sagittal split ramus osteotomy (SSRO) was designed in 10 hemimandibles (group 1) with a vertical osteotomy in the buccal side (second molar level) and final osteotomy was performed horizontally on the lingual aspect, while the mandible body osteotomy was finalized as a straight osteotomy in the basilar area, perpendicular to the body. For group 2, the same osteotomy technique was used, but an oblique osteotomy was done in the basilar aspect of the mandibular body, forming continuity with the sagittal cut in the basilar area. Using a surgical guide, osteosynthesis was performed with bicortical screws using an inverted L scheme. In both groups vertical compression tests were performed with a linear load of 1 mm/min on the central fossa of the first molar and tests were done with models made from photoelastic resin. Data were analyzed using Student's t-test, establishing a statistical significance when P <0.05.
  
  
  RESULTS
  A statistical difference was not observed in the maximum displacements obtained in the two osteotomies (P <0.05). In the extensiometric analysis, statistically significant differences were identified only in the middle screw of the fixation. The photoelastic resin models showed force dissipation towards the inferior aspect of the mandible in both SSRO models.
  
  
  CONCLUSIONS
  We found that osteotomy of the inferior aspect did not influence the mechanical performance for osteosynthesis with an inverted L system.
authors.affiliation: Department of Oral and Maxillofacial Surgery, State University of Campinas, São Paulo, Brazil.
authors.forename: Valdir Cabral
authors.initials: VC
authors.lastname: Andrade
authors.affiliation: Department of Oral Rehabilitation and Periodontics, State University of Campinas, São Paulo, Brazil.
authors.forename: Leonardo Flores
authors.initials: LF
authors.lastname: Luthi
authors.affiliation: Department of Oral and Maxillofacial Surgery, State University of Campinas, São Paulo, Brazil.
authors.forename: Fabio Loureiro
authors.initials: FL
authors.lastname: Sato
authors.affiliation: Department of Oral and Maxillofacial Surgery, State University of Campinas, São Paulo, Brazil.
authors.forename: Leandro
authors.initials: L
authors.lastname: Pozzer
authors.affiliation: Department of Oral and Maxillofacial Surgery, Universidad de La Frontera, Temuco, Chile. ; Center for Biomedical Research, Universidad Autónoma de Chile, Temuco, Chile.
authors.forename: Sergio
authors.initials: S
authors.lastname: Olate
authors.affiliation: Department of Oral and Maxillofacial Surgery, State University of Campinas, São Paulo, Brazil.
authors.forename: Jose Ricardo
authors.initials: JR
authors.lastname: Albergaria-Barbosa
keywords: Mandibular osteotomy; Rigid internal fixation; Sagittal split ramus osteotomy