title: Stress distribution in implant-supported prosthesis with external and internal implant-abutment connections.
abstract: OBJECTIVE
  This study aimed to investigate the stress distribution in screwed implant-supported prostheses with different implant-abutment connections by using a photoelastic analysis.
  
  
  METHODS
  Four photoelastic models were fabricated in PL-2 resin and divided according to the implant-abutment connection (external hexagon (EH) and Morse taper (MT) implants (3.75 × 11.5 mm)) and the number crowns (single and 3-unit piece). Models were positioned in a circular polariscope and 100-N axial and oblique (45) loading were applied in the occlusal surface of the crowns by using a universal testing machine. The stresses were photographically recorded and qualitatively analyzed using software (Adobe Photoshop).
  
  
  RESULTS
  Under axial loading, the MT implants exhibited a lower number of fringes for single-unit crowns than EH implants, whereas for a 3-unit piece the MT implants showed a higher number of fringes vs EH implants. The oblique loading increased the number of fringes for all groups.
  
  
  CONCLUSIONS
  In conclusion, the MT implant-abutment connection reduced the amount of stress in single-unit crowns, for 3-unit piece crowns the amount of stress was lower using an external hexagon connection. The stress pattern was similar for all groups. Oblique loading promoted a higher stress concentration than axial loading.
authors.affiliation: Department of Dental Materials and Prosthodontics, Araçatuba School of Dentistry, São Paulo State University-UNESP, Araçatuba, São Paulo, Brazil. goiato@foa.unesp.br
authors.forename: Marcelo
authors.initials: M
authors.lastname: Coelho Goiato
authors.forename: Aldiéris Alves
authors.initials: AA
authors.lastname: Pesqueira
authors.forename: Rosse Mary
authors.initials: RM
authors.lastname: Falcón-Antenucci
authors.forename: Daniela Micheline
authors.initials: DM
authors.lastname: Dos Santos
authors.forename: Marcela Filié
authors.initials: MF
authors.lastname: Haddad
authors.forename: Lisiane Cristina
authors.initials: LC
authors.lastname: Bannwart
authors.forename: Amália
authors.initials: A
authors.lastname: Moreno
mesh_terms: D001696:Biomechanical Phenomena; D059605:Dental Implant-Abutment Design; D015921:Dental Implants; D006801:Humans; D008962:Models, Theoretical
chemical_list: D015921:Dental Implants