In vitro evaluation of the precision of working casts for implant-supported restoration with multiple abutments.
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.
Castilho
Anderson Almeida
AA
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
Kojima
Alberto Noriyuki
AN
Pereira
Sarina Maciel Braga
SM
de Vasconcellos
Diego Klee
DK
Itinoche
Marcos Koiti
MK
Faria
Renata
R
Bottino
Marco Antonio
MA