title: Stress distribution around maxillary implants in anatomic photoelastic models of varying geometry. Part I.
abstract: BACKGROUND
  It is unclear which implant inclination and position are most favorable in relation to the supporting anatomy and loading direction in the maxilla.
  
  
  OBJECTIVE
  This study was designed to examine stress distribution around implants in a 2-dimensional photoelastic anatomic model.
  
  
  METHODS
  Two 2-dimensional photoelastic models were prepared with opposing 8-degree cylinder metal implant and molar teeth analogues. A frontal anatomic sectional plate model based on a CT section at the first molar was symmetrically loaded through its long axis. A midfacial rectangular model based on the same section was loaded in a different direction with varying supporting geometries.
  
  
  RESULTS
  Stress distribution around the maxillary implant was highest in the buccal concavity at the apical buccal third and in the lingual concavity on intercuspal loading. No stress concentration occurred at the implant apex under the sinus for axial and nonaxial loading in both anatomic model geometries. On lateral loading, stress concentration was observed at the buccal concavity and at the implant neck. In the midfacial block model, principal stresses were concentrated at the maxillary implant neck on nonaxial loading and at the apex on axial loading.
  
  
  CONCLUSIONS
  This 2-dimensional skull model showed different patterns of stress distribution among the maxillary implant, mandibular implant, and teeth. The highest principal stress concentration was seen at the buccal concavity of the maxillary implant; this may play a role in osseointegration with highly angled implants in the posterior maxilla. Differences in stress distribution between anatomic and nonanatomic models showed how the supporting geometry (for example, sinus/nasal anatomy), boundary conditions, and loading direction influence stress distribution.
authors.affiliation: The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel. grossmd@post.tau.ac.il
authors.forename: M D
authors.initials: MD
authors.lastname: Gross
authors.forename: J
authors.initials: J
authors.lastname: Nissan
authors.forename: R
authors.initials: R
authors.lastname: Samuel
mesh_terms: D001718:Birefringence; D015519:Bone Density; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D003799:Dental Stress Analysis; D004548:Elasticity; D006801:Humans; D008437:Maxilla / Q000502:physiology*; D008443:Maxillary Sinus / Q000502:physiology; D008953:Models, Anatomic; D003765:Models, Dental; D008963:Molar / Q000502:physiology; D012886:Skull; D016474:Weight-Bearing
chemical_list: D015921:Dental Implants