title: Stress on external hexagon and Morse taper implants submitted to immediate loading.
abstract: OBJECTIVE
  This study aimed to evaluate the stress distribution around external hexagon (EH) and Morse taper (MT) implants with different prosthetic systems of immediate loading (distal bar (DB), casting technique (CT), and laser welding (LW)) by using photoelastic method.
  
  
  METHODS
  Three infrastructures were manufactured on a model simulating an edentulous lower jaw. All models were composed by five implants (4.1 mm × 13.0 mm) simulating a conventional lower protocol. The samples were divided into six groups. G1: EH implants with DB and acrylic resin; G2: EH implants with titanium infrastructure CT; G3: EH implants with titanium infrastructure attached using LW; G4: MT implants with DB and acrylic resin; G5: MT implants with titanium infrastructure CT; G6: MT implants with titanium infrastructure attached using LW. After the infrastructures construction, the photoelastic models were manufactured and a loading of 4.9 N was applied in the cantilever. Five pre-determined points were analyzed by Fringes software.
  
  
  RESULTS
  Data showed significant differences between the connection types (p < 0.0001), and there was no significant difference among the techniques used for infrastructure.
  
  
  CONCLUSIONS
  The reduction of the stress levels was more influenced by MT connection (except for CT). Different bar types submitted to immediate loading not influenced stress concentration.
authors.affiliation: MSc, Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Caroline H
authors.initials: CH
authors.lastname: Odo
authors.affiliation: PhD, Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Marcele J
authors.initials: MJ
authors.lastname: Pimentel
authors.affiliation: Associated Professor, Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Rafael L X
authors.initials: RL
authors.lastname: Consani
authors.affiliation: Professor, Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Marcelo F
authors.initials: MF
authors.lastname: Mesquita
authors.affiliation: Professor, Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Mauro A A
authors.initials: MA
authors.lastname: Nóbilo
keywords: Dental casting technique; Dental implants; Dental soldering; Distal bar; Photoelastic analysis