Analysis of the Mechanical Behavior and Surface Rugosity of Different Dental Die Materials.
OBJECTIVE
This work evaluated the mechanical and surface behavior of different die materials. The studied materials are polyurethane resin Exakto-Form (Bredent), Gypsum type IV, Fuji Rock EP (Gc), and Durone (Dentsply).


METHODS
Two metallic matrices molded in polyvinyl siloxane provided 30 cylindrical test specimens for the diametral compression test and 30 hemispherical test specimens for the surface rugosity test. The cylindrical test specimens were submitted to tests of diametral compression strength using a DL2000 universal assay machine, with a load cell of 2000 Kgf and constant speed of 1 mm/min connected to the software. Kruskal-Wallis and Dunn's nonparametric tests were used to analyze the results. The hemispheres were submitted to the surface rugosity assay using a SJ201-P rugosimeter with a sensitivity of 300 μm, speed of 0.5 mm/s, and cut-off of 0.8 mm, and the readings were taken on the convex surface of the test specimens and metallic matrix. Results were analyzed using with Fisher's least significant differences test (LSD) and Dunnett's test.


RESULTS
Kruskal-Wallis test showed significant difference between die materials for diametral compression strength (P= 0.002). Dunn's test showed significantly higher values for modified polyurethane resin (Exakto-Form). The gypsum type IV, which did not significantly differ regarding diametral compression strength, showed 34.0% (Durone) and 42.7% (Fuji Rock) lower values in comparison to Exakto-Form.


CONCLUSIONS
Within the parameters adopted in this study, it is possible to conclude that Exakto-Form polyurethane resin showed higher resistance to compression and was closer to the metallic matrix rugosity, and, along with the gypsum type IV Durone, showed better reproducibility of details relative to the Fuji Rock.
Department of Restorative Dentistry, São Leopoldo Mandic Dental School, Campinas-São Paulo, Brazil.
Ciro T
CT
Niekawa
Department of Restorative Dentistry, São Leopoldo Mandic Dental School, Campinas-São Paulo, Brazil.
Simone
S
Kreve
Department of Restorative Dentistry, São Leopoldo Mandic Dental School, Campinas-São Paulo, Brazil.
Gisseli Bertozzi
GB
A'vila
Department of Restorative Dentistry, São Leopoldo Mandic Dental School, Campinas-São Paulo, Brazil.
Gilmar Gil
GG
Godoy
Department of Restorative Dentistry, São Leopoldo Mandic Dental School, Campinas-São Paulo, Brazil.
J R
JR
Eduardo Vieira da Silva
Department of Restorative Dentistry, São Leopoldo Mandic Dental School, Campinas-São Paulo, Brazil.
Sergio Candido
SC
Dias
Calcium sulphate; dental casting technique; dental die materials; dental marginal adaption; dental prosthesis; synthetic resins