title: Hourglass mandibular anatomic variant incidence and treatment considerations for all-on-four implant therapy: report of 10 cases.
abstract: OBJECTIVE
  The purpose of this study was to determine the incidence and treatment of hour glass variant mandibles for All On Four implant placement.
  
  
  METHODS
  Cone beam CAT scans were analyzed for 719 patients to determine the incidence of alveolar constriction in the mandible. Ten patients with alveolar constriction were treated over a 2-year period and retrospectively studied after 1 year in function.
  
  
  RESULTS
  Of 719 mandibles studied, 28 have "hour glass" variants identified for an incidence of 3.89%. Treatment of these cases were variously done including the use of guided bone regeneration, the use of long implants, bone reduction, and angulation strategies.
  
  
  CONCLUSIONS
  The hour glass mandibular finding is a developmental or genetic variant that poses a significant anatomic difficulty for dental implant surgery for All On Four immediate function.
authors.affiliation: ClearChoice Dental Implant Center, Phoenix, AZ, USA.
authors.forename: Caesar C
authors.initials: CC
authors.lastname: Butura
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Galindo
authors.forename: Jared
authors.initials: J
authors.lastname: Cottam
authors.forename: Mark
authors.initials: M
authors.lastname: Adams
authors.forename: Ole
authors.initials: O
authors.lastname: Jensen
mesh_terms: D000328:Adult; D000368:Aged; D000539:Alveolar Process / Q000473:pathology; D000543:Alveoloplasty / Q000379:methods; D001861:Bone Regeneration / Q000502:physiology; D018786:Bone Substitutes / Q000627:therapeutic use; D016025:Bone Transplantation / Q000379:methods; D054893:Cone-Beam Computed Tomography; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003779:Denture Design; D005260:Female; D005500:Follow-Up Studies; D048091:Guided Tissue Regeneration / Q000379:methods; D006801:Humans; D057893:Immediate Dental Implant Loading; D008297:Male; D008334:Mandible / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D008903:Minerals / Q000627:therapeutic use; D010027:Osteotomy / Q000379:methods; D016300:Radiography, Bitewing; D011862:Radiography, Panoramic; D012189:Retrospective Studies
chemical_list: C077540:Bio-Oss; D018786:Bone Substitutes; D015921:Dental Implants; D008903:Minerals