title: Photoelastic stress analysis of load transfer to implants and natural teeth comparing rigid and semirigid connectors.
abstract: BACKGROUND
  Controversy exists regarding the connection of implants to natural teeth.
  
  
  OBJECTIVE
  This simulation study measured photoelastically the biologic behavior of implants. Stress transfer patterns with variable implant support and simulated natural teeth through rigid and nonrigid connection were examined under simulated functional loads.
  
  
  METHODS
  A photoelastic model of a human left mandible edentulous distal to first premolar was fabricated having 2 screw type implants (3.75x13 mm) embedded within the edentulous area. Two fixed prosthetic restorations were fabricated with either a nonsplinted proximal contact or a soldered proximal contact, and cast precision dowel attachment between implant areas and simulated tooth. Simulated vertical occlusal loads were applied at fixed locations on the restorations. Stresses, which developed in the supporting structure, were monitored photoelastically and recorded photographically.
  
  
  RESULTS
  The rigid connector in the 1 implant situation caused only slightly higher stresses in the supporting structure than the nonrigid connector. The distally loaded 1 and 2 implant-supported restoration produced the highest apical stresses, which occurred at the distal implant. The rigid connector demonstrated the greatest stress transfer in the 2 implant-supported restoration.
  
  
  CONCLUSIONS
  Lower stresses apical to the tooth or implant occurred with forces applied further from the supporting abutment. Although the least stress was observed when using a nonrigid connector, the rigid connector in particular situations caused only slightly higher stresses in the supporting structure. The rigid connector demonstrated more widespread stress transfer in the 2 implant-supported restoration. Recommendations for selection of connector design should be based on sound clinical periodontal health of a tooth and the support provided by implants.
authors.affiliation: Division of Advanced Prosthodontics, Biomaterials, and Hospital Dentistry, School of Dentistry, University of California, Los Angeles, Calif, USA.
authors.forename: R D
authors.initials: RD
authors.lastname: Nishimura
authors.forename: K T
authors.initials: KT
authors.lastname: Ochiai
authors.forename: A A
authors.initials: AA
authors.lastname: Caputo
authors.forename: C M
authors.initials: CM
authors.lastname: Jeong
mesh_terms: D000328:Adult; D001732:Bite Force; D000044:Dental Abutments; D015921:Dental Implants; D019094:Dental Prosthesis, Implant-Supported; D012994:Dental Soldering; D003799:Dental Stress Analysis / Q000379:methods; D003779:Denture Design; D003834:Denture Precision Attachment; D003830:Denture, Partial, Fixed; D004548:Elasticity; D006801:Humans; D008027:Light; D008334:Mandible / Q000502:physiology; D008953:Models, Anatomic; D010519:Periodontium / Q000502:physiology; D010781:Photography; D013314:Stress, Mechanical; D014070:Tooth / Q000502:physiology*; D019227:Tooth Apex / Q000502:physiology
chemical_list: D015921:Dental Implants