title: Morphologic classification and stress analysis of the mandibular bone in the premolar region for implant placement.
abstract: OBJECTIVE
  The objective of this study was to assess the influence of mandibular morphology on the stress and strain distributions in the bone supporting an implant.
  
  
  METHODS
  Subjects were selected from patients with missing mandibular premolar teeth. Computed tomographic scans of the premolar region were classified into nine groups based on the overall bone morphology and the relative position of the alveolar crest. Finite element models of the bone on the basis of this classification, with inserted implants and superstructures, were constructed. A load of 200 N applied 30 degrees buccal from the vertical axis was directed toward the occlusal surface.
  
  
  RESULTS
  One hundred two partially (n = 98) and completely (n = 4) edentulous subjects were recruited. Their ages ranged from 40 to 79 years (mean age, 60.5 years; 41 men and 61 women). Approximately 56% of the patients showed bone widening in the caudal direction. The maximum compressive stresses were shown in the lingual cervical regions. An influence of overall bone morphology on stress distribution was not observed; however, the alveolar crest contour clearly affected the maximum stress and strain values. Compressive microstrain above 4,000 was observed only when the alveolar crest was lingually located relative to the body of the mandible. These high strain levels were concentrated at the lingual cervical margin, with volumes ranging from 0.04 to 0.07 mm3.
  
  
  CONCLUSIONS
  The contour of the alveolar crest potentially plays a critical role in maintaining the bone levels surrounding implants.
authors.affiliation: Department of Oral Implantology and Regenerative Dental Medicine, Graduate School and GCOE Program, International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan.
authors.forename: Malik
authors.initials: M
authors.lastname: Hudieb
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Wakabayashi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Suzuki
authors.forename: Shohei
authors.initials: S
authors.lastname: Kasugai
mesh_terms: D000328:Adult; D000368:Aged; D000539:Alveolar Process / Q000473:pathology*; D001641:Bicuspid; D019245:Compressive Strength; D003198:Computer Simulation; D015921:Dental Implants; D003799:Dental Stress Analysis / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D007576:Jaw, Edentulous, Partially / Q000145:classification* / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging / Q000473:pathology*; D008875:Middle Aged; D013718:Tensile Strength; D014057:Tomography, X-Ray Computed
chemical_list: D015921:Dental Implants