title: In vitro comparison of 1.5 mm vs. 2.0 mm screws for fixation in the sagittal split osteotomy.
abstract: OBJECTIVE
  Numerous "in vitro" investigations have been conducted to evaluate the role of screw size and pattern in determining optimal resistance to deformation, often these have been controversial. The aim of this study was to evaluate the effect of screw size and insertion technique on the stability of sagittal split osteotomies.
  
  
  METHODS
  This study used twenty polyurethane replicas of human hemimandibles with a prefabricated sagittal split ramus osteotomy (SSRO). The hemimandibles were stabilized with 1.5 mm and 2.0 mm titanium screws inserted in an inverted L configuration. All specimens were tested to determine the strength and stability of the fixation.
  
  
  RESULTS
  In all cases there was failure of the synthetic bone before there was any evidence of screw failure. There were no significant differences in the load necessary to make the construct fail between the 1.5 or 2.0 mm screw sizes.
  
  
  CONCLUSIONS
  There was no statistically significant difference between the strengths achieved with screws of 1.5 and 2.0 mm diameters for fixation of SSRO performed in synthetic mandibles. There was no fracture of the 1.5 mm or 2.0 mm diameter screws in any of the tests. 1.5 mm diameter screws in an inverted L pattern have as much stability and mechanical resistance as a 2.0 mm screw, may be safely used for this procedure.
authors.affiliation: Department of Diagnosis and Surgery, São Paulo State University-UNESP, Rua Humaitá, 1680, 14801-903 Araraquara (SP), Brazil. molon.foar@yahoo.com.br
authors.forename: Rafael
authors.initials: R
authors.lastname: Scaf de Molon
authors.forename: Érica Dorigatti
authors.initials: ÉD
authors.lastname: de Ávila
authors.forename: Guilherme Romano
authors.initials: GR
authors.lastname: Scartezini
authors.forename: Juliana Alvares Duarte
authors.initials: JA
authors.lastname: Bonini Campos
authors.forename: Luis Geraldo
authors.initials: LG
authors.lastname: Vaz
authors.forename: Mario Francisco
authors.initials: MF
authors.lastname: Real Gabrielli
authors.forename: Valfrido Antônio
authors.initials: VA
authors.lastname: Pereira Filho
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D001696:Biomechanical Phenomena; D001863:Bone Screws; D004867:Equipment Design; D006801:Humans; D008334:Mandible / Q000033:anatomy & histology / Q000601:surgery*; D008422:Materials Testing; D008953:Models, Anatomic; D059229:Osteotomy, Sagittal Split Ramus / Q000295:instrumentation* / Q000379:methods; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D014025:Titanium