title: Assessment of the fixation of mandibular symphysis fractures using conical cannulated screws: mechanical and photoelastic tests.
abstract: OBJECTIVE
  The aim of this study was to use mechanical and photoelastic tests to compare the performance of cannulated screws with other fixation methods in mandibular symphysis fractures.
  
  
  METHODS
  Ten polyurethane mandibles were allocated to each group and fixed as follows: group PRP, 2 perpendicular miniplates; group PLL, 1 miniplate and 1 plate, parallel; and group CS, 2 cannulated screws. Vertical linear loading tests were performed. The differences between mean values were analyzed with the Tukey test. The photoelastic test was carried out using a polariscope.
  
  
  RESULTS
  The results revealed differences between the CS and PRP groups at 1, 3, 5, and 10 millimeters of displacement. The photoelastic test confirmed higher stress concentration in all groups close to the mandibular base, whereas the CS group showed it throughout the region assessed.
  
  
  CONCLUSIONS
  Conical cannulated screws performed well in mechanical and photoelastic tests.
authors.affiliation: Oral and Maxillofacial Surgery Section, Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil. Electronic address: 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), Piracicaba, São Paulo, Brazil.
authors.forename: Danillo Costa
authors.initials: DC
authors.lastname: Rodrigues
authors.affiliation: Private practice.
authors.forename: Erica Cristina
authors.initials: EC
authors.lastname: Marchiori
authors.affiliation: Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil.
authors.forename: Giulia
authors.initials: G
authors.lastname: Brancher
authors.affiliation: Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil.
authors.forename: Andréia
authors.initials: A
authors.lastname: Makyama
authors.affiliation: Oral and Maxillofacial Surgery Section, Oral Diagnosis Department, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, São Paulo, Brazil.
authors.forename: Roger William
authors.initials: RW
authors.lastname: Fernandes Moreira
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D003799:Dental Stress Analysis; D004548:Elasticity; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D066298:In Vitro Techniques; D008337:Mandibular Fractures / Q000601:surgery*; D003765:Models, Dental; D011474:Prosthesis Design