title: Morphologic basis for the intraoral vertical ramus osteotomy: anatomic and radiographic localization of the mandibular foramen.
abstract: OBJECTIVE
  The study goals were to provide anatomic and radiographic parameters that permit the performance of an intraoral vertical ramus osteotomy (IVRO) without violation of the mandibular foramen (Fm) and to evaluate the usefulness of the LeVasseur-Merrill retractor (Walter Lorenz Surgical, Jacksonville, FL) developed for IVRO.
  
  
  METHODS
  Two hundred eighty dry adult human mandibular rami were measured, directly and via panoramic radiography, to obtain the horizontal and vertical positions of the Fm in the mandibular ramus. Measurements of the dry mandible were also compared with the radiographs to estimate Fm location.
  
  
  RESULTS
  The Fm is located approximately at the posterior third of the ramus, in both the vertical and horizontal directions. The Fm was located within 7 mm of the posterior edge of the mandible in only 3.3% of the rami. Radiographic distortion of the total length of the ramus was an average of only 0.9%. The LeVasseur-Merrill retractor was effective in 98.9% of the analyzed rami.
  
  
  CONCLUSIONS
  Estimation of the Fm position during surgery on the posterior edge of the ramus is useful. Measurement of the ramus width, performed with preoperative panoramic radiography, effectively locates the Fm. The LeVasseur-Merrill retractor, when correctly positioned, was an effective tool in determining the appropriate thickness of the IVRO proximal fragment.
authors.affiliation: Morphology Postgraduate Program, Biology Institute/State University of Rio de Janeiro, Brazil. renatofontoura@aol.com
authors.forename: Renato Aló
authors.initials: RA
authors.lastname: da Fontoura
authors.forename: Henrique Ayres
authors.initials: HA
authors.lastname: Vasconcellos
authors.forename: Antonio Eduardo Siqueira
authors.initials: AE
authors.lastname: Campos
mesh_terms: D000328:Adult; D006801:Humans; D008334:Mandible / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery*; D008340:Mandibular Nerve / Q000033:anatomy & histology; D019647:Oral Surgical Procedures / Q000295:instrumentation* / Q000379:methods*; D010027:Osteotomy / Q000379:methods*; D011862:Radiography, Panoramic; D012016:Reference Values; D015203:Reproducibility of Results