Evaluation of the use of die spacer over the marginal fit of casting copings of Ni-Cr, Ni-Cr-Be and commercially pure Titanium

Author(s)

Natércia Carreira Soriani

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Ribeirão Preto (PCARP/BC)
• Defense date: 2008-02-01

Examining board members

Osvaldo Luiz Bezzon; Guilherme Elias Pessanha Henriques; Valéria Oliveira Pagnano de Souza

• Advisor: Osvaldo Luiz Bezzon

Abstract

The purpose of the study was to evaluate the effect of using die spacers on the marginal fit of Ni Cr (Verabond II) (VB II) and Ni-Cr-Be (Verabond) (VB) alloys and commercially pure Titanium (Tritan) (Ti-cp) casting copings by the lost wax technique. Using a metal master die, 135 Resin Added Extra Hard Type IV Stone were obtained for the fabrication of wax patterns in the following conditions: without die spacer (G0), with one die spacer layer (G1); and with two die spacer layers (G2), with fifteen repetitions for each group. Each stone die was waxed and the wax patterns were invested as recommended by the manufacturer. Three wax patterns were embedded in each casting ring, each corresponding to a condition. Each coping, seated to the metal matrix by a Seating Pressure Standardizing Device (SPSD), was taken to the Optic Microscope for the measurement of marginal discrepancy. The obtained data (&micro;m) were submitted to statistical analysis (ANOVA) and Tukey test (p<0.05). There was not statistically significant difference among the materials VB II (93,40) and VB (118,73), and there was statistically significant different to Ti-cp (168,35) . In terms of the die spacer, there was a statistically significant difference among the three conditions (G0=177,31; G1=121,51 e G2=81,66). It was concluded that with two die spacer layers there is less marginal discrepancy. (AU)