title: In vitro evaluation of the precision of working casts for implant-supported restoration with multiple abutments.
abstract: OBJECTIVE
  The purpose of this study was to compare the accuracy of two working cast fabrication techniques using strain-gauge analysis.
  
  
  METHODS
  Two working cast fabrication methods were evaluated. Based on a master model, 20 working casts were fabricated by means of an indirect impression technique using polyether after splinting the square transfer copings with acrylic resin. Specimens were assigned to 2 groups (n=10): Group A (GA): type IV dental stone was poured around the abutment analogs in the conventional way; Group B (GB), the dental stone was poured in two stages. Spacers were used over the abutment analogs (rubber tubes) and type IV dental stone was poured around the abutment analogs in the conventional way. After the stone had hardened completely, the spacers were removed and more stone was inserted in the spaces created. Six strain-gauges (Excel Ltd.), positioned in a cast bar, which was dimensionally accurate (perfect fit) to the master model, recorded the microstrains generated by each specimen. Data were analyzed statistically by the variance analysis (ANOVA) and Tukey's test (I+/-= 5%).
  
  
  RESULTS
  The microstrain values (microepsilon) were (mean+/-SD): GA: 263.7+/-109.07microepsilon, and GB: 193.73+/-78.83microepsilon.
  
  
  CONCLUSIONS
  There was no statistical difference between the two methods studied.
authors.affiliation: Department of Dental Materials and Prosthodontics, Dental School of São José dos Campos, São Paulo State University Júlio de Mesquita Filho, São José dos Campos, SP, Brazil. andercast@yahoo.com.br
authors.forename: Anderson Almeida
authors.initials: AA
authors.lastname: Castilho
authors.forename: Alberto Noriyuki
authors.initials: AN
authors.lastname: Kojima
authors.forename: Sarina Maciel Braga
authors.initials: SM
authors.lastname: Pereira
authors.forename: Diego Klee
authors.initials: DK
authors.lastname: de Vasconcellos
authors.forename: Marcos Koiti
authors.initials: MK
authors.lastname: Itinoche
authors.forename: Renata
authors.initials: R
authors.lastname: Faria
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Bottino