title: Biomechanics of the mandible part I: measurement of mandibular functional deformation using custom-fabricated displacement transducers.
abstract: OBJECTIVE
  The purpose of this study was to measure corporal approximation, dorsoventral shear, and corporal rotation in edentulous subjects treated with dental implants, during normal mandibular movements.
  
  
  METHODS
  Three patterns of jaw deformation (corporal approximation [CA], corporal rotation [CR], and dorsoventral [DV] shear) were measured using custom-fabricated displacement transducers in 12 edentulous subjects who had been treated with dental implants. Measurements were made in real time using a multichannel analogue/digital converter and a personal computer for data storage and analysis. Corporal approximation was measured as the linear change in the orientation of the 2 implants in the horizontal plane. Corporal rotation was recorded as a relative rotation of the right and left mandibular bodies projected into the frontal plane, and dorsoventral shear as the relative rotation of the 2 implants projected onto the median sagittal plane.
  
  
  RESULTS
  All 3 patterns of mandibular deformation occurred concurrently and immediately on commencement of jaw movement. Different jaw movements produced different patterns of mandibular deformation. The highest values of jaw deformation were recorded during protrusion. CA ranged between 11.0 microm and 57.8 microm. Corporal rotation and DV shear ranged between 0.4 degrees and 2.8 degrees .
  
  
  CONCLUSIONS
  This clinical study shows and measures 3 different and concurrent patterns of jaw deformation, during normal mandibular movements, using custom fabricated displacement transducers. The transducers may have a potential for routine clinical applications.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Helsinki University Hospital, Helsinki, Finland. Jehad.Al-Sukhun@hus.fi
authors.forename: Jehad
authors.initials: J
authors.lastname: Al-Sukhun
authors.forename: Miia
authors.initials: M
authors.lastname: Helenius
authors.forename: Christian
authors.initials: C
authors.lastname: Lindqvist
authors.forename: John
authors.initials: J
authors.lastname: Kelleway
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D001732:Bite Force; D002508:Cephalometry; D015921:Dental Implants; D003799:Dental Stress Analysis / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D007574:Jaw Relation Record; D007575:Jaw, Edentulous / Q000503:physiopathology*; D016018:Least-Squares Analysis; D008334:Mandible / Q000503:physiopathology*; D008875:Middle Aged; D009068:Movement; D012399:Rotation; D033081:Shear Strength; D013314:Stress, Mechanical; D014159:Transducers
chemical_list: D015921:Dental Implants