title: External hexagon and internal hexagon in straight and offset implant placement: strain gauge analysis.
abstract: OBJECTIVE
  : The objective of this in vitro study was to quantify the strain development of external hexagon and internal hexagon implant-supported partial prostheses in straight and offset implant placement configurations.
  
  
  METHODS
  : Three external hexagon and 3 internal hexagon implants were embedded in the center of each polyurethane block. Four strain gauges were bonded on the surface of polyurethane. The 20 superstructure occlusal screws were tightened onto the Microunit abutments with a torque of 10 Ncm using the manufacturer's manual of torque-controlling device.
  
  
  RESULTS
  : There were statistic significant differences in hexagonal type (P = 0.0210 < 0.05). There were nostatistic significant differences in placement configuration (P = 0.7483 > 0.05). The results showed fundamental differences between both conditions.
  
  
  CONCLUSIONS
  : Under the limited conditions of this study, the hexagon internal connection displayed higher values of microstrain than the hexagon external type implant placement. There was no evidence that there was an advantage of offset placement in reducing the strain around implant. There was no proof from this investigation that the straight placement generated higher microstrain than offset placement.
authors.affiliation: Department of Dental Materials and Prosthodontics, School of Dentistry of São José dos Campos, São Paulo State University (UNESP), São José dos Campos, 12245-000, SP, Brazil. nishiokaunesp@gmail.com
authors.forename: Renato Sussumu
authors.initials: RS
authors.lastname: Nishioka
authors.forename: Luis Gustavo Oliveira
authors.initials: LG
authors.lastname: de Vasconcellos
authors.forename: Lea Nogueira Braulino
authors.initials: LN
authors.lastname: de Melo Nishioka
mesh_terms: D002858:Chromium Alloys / Q000737:chemistry; D000044:Dental Abutments; D003734:Dental Casting Investment / Q000737:chemistry; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D018772:Dental Marginal Adaptation; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003829:Denture, Partial; D006801:Humans; D008422:Materials Testing; D013314:Stress, Mechanical; D013499:Surface Properties; D019415:Torque
chemical_list: D002858:Chromium Alloys; D003734:Dental Casting Investment; D015921:Dental Implants