title: Mechanical and photoelastic analysis of conventional screws and cannulated screws for sagittal split osteotomy fixation: a comparative study.
abstract: OBJECTIVE
  The aim of the present study was to use mechanical and photoelastic tests to compare the performance of cannulated screws with solid-core screws in sagittal split osteotomy fixation.
  
  
  METHODS
  Ten polyurethane mandibles, with a prefabricated sagittal split ramus osteotomy, were fixed with an L inverted technique and allocated to each group as follows: cannulated screw group (CSG), fixed with three 2.3-cannulated screws; and solid-core screw group (SCSG), fixed with three 2.3-solid-core screws. Vertical linear loading tests were performed. The differences between mean values were analyzed through T test for independent samples. The photoelastic test was carried out using a polariscope.
  
  
  RESULTS
  The results revealed differences between the two groups only at 1 mm of displacement, in which the cannulated-screw revealed more resistance. Photoelastic test showed higher stress concentration close to mandibular branch in the solid-core group.
  
  
  CONCLUSIONS
  Cannulated screws performed better than solid-core ones in a mechanical test at 1-mm displacement and photoelastic tests.
authors.affiliation: Oral and Maxillofacial Surgery Section, Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Tiradentes, 195, Diamantina, MG, 39100-000, Brazil.|Oral and Maxillofacial Surgery Section, Oral Diagnosis Department, Brazilian Navy, Brasilia, Brazil.
authors.forename: Cristina Jardelino de
authors.initials: CJ
authors.lastname: Lima
authors.affiliation: Oral and Maxillofacial Surgery Section, Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Tiradentes, 195, Diamantina, MG, 39100-000, Brazil. saulofalci@hotmail.com.|Hospital Santa Casa de Caridade de Diamantina, Diamantina, Brazil. saulofalci@hotmail.com.
authors.forename: Saulo Gabriel Moreira
authors.initials: SG
authors.lastname: Falci
authors.affiliation: Oral and Maxillofacial Surgery Section, Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Tiradentes, 195, Diamantina, MG, 39100-000, Brazil.|Hospital Santa Casa de Montes Claros, Montes Claros, Brazil.
authors.forename: Danillo Costa
authors.initials: DC
authors.lastname: Rodrigues
authors.affiliation: Oral and Maxillofacial Surgery Section, Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Tiradentes, 195, Diamantina, MG, 39100-000, Brazil.
authors.forename: Érica Cristina
authors.initials: ÉC
authors.lastname: Marchiori
authors.affiliation: Oral and Maxillofacial Surgery Section, Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Tiradentes, 195, Diamantina, MG, 39100-000, Brazil.
authors.forename: Roger Willian Fernandes
authors.initials: RW
authors.lastname: Moreira
mesh_terms: D001863:Bone Screws; D004548:Elasticity; D008027:Light; D008422:Materials Testing; D059229:Osteotomy, Sagittal Split Ramus; D011140:Polyurethanes
chemical_list: D011140:Polyurethanes
keywords: Cannulated screw; Orthognathic surgery; Sagittal osteotomy; Surgical fixation devices