title: Helical axis errors affect computer-generated occlusal contacts.
abstract: A helical axis describing mandibular motion can be calculated from two distinct positions of the mandible; however, as these positions come closer together, calculation errors increase. This study investigated the effects of errors in the calculated helical axis on simulated mandibular motion by the measurement of changes in occlusal contacts. A standard helical axis was calculated from a simulated lateral movement. A series of digital interocclusal records from centric to a 5 degree mandibular rotation about the standard helical axis was created. Digital dental cast models were aligned to the interocclusal records. Helical axis parameters and occlusal contacts calculated with the use of the aligned digital models were compared with those of the standard. Helical axes calculated from mandibular positions separated by 1.5 degrees to 5.0 degrees yielded equivalent occlusal contacts. Qualitatively, contacts for helical axes calculated from jaw rotations of 0.7 degrees or larger were nearly identical to those of the standard.
authors.affiliation: Minnesota Dental Research Center for Biomaterials and Biomechanics, Department of Oral Science, University of Minnesota School of Dentistry, Moos Health Science Tower, 515 Delaware Street SE, Minneapolis, MN 55455, USA. delon002@tc.umn.edu
authors.forename: R
authors.initials: R
authors.lastname: DeLong
authors.forename: C-C
authors.initials: CC
authors.lastname: Ko
authors.forename: I
authors.initials: I
authors.lastname: Olson
authors.forename: J S
authors.initials: JS
authors.lastname: Hodges
authors.forename: W H
authors.initials: WH
authors.lastname: Douglas
mesh_terms: D003198:Computer Simulation; D003725:Dental Articulators; D003766:Dental Occlusion; D006801:Humans; D021621:Imaging, Three-Dimensional; D007574:Jaw Relation Record / Q000379:methods; D008334:Mandible / Q000502:physiology; D003765:Models, Dental; D009068:Movement; D015203:Reproducibility of Results