Marginal fit of electroformed copings before and after the coction of the porcelain

Abstract

The aim of this study was to evaluate the marginal discrepancy of electroforming copings, before and after the porcelain application, varying the cervical preparation of the crowns.Two master die were prepared with stainless steel to complete crown margin designs: chamfer and rounded shoulder. The impressions were taken with a polyvinylsiloxane by the double impression technique and, the insertion and removal axis were standardized by a dental surveyor. Ten type IV plaster dies from each cervical margin were obtained, on which a die spacer was applied before duplicate. The duplicated dies received a silver layer and connected to a copper wire to enable the gold electrodeposition. After cleaning and adjustments all specimens were examined under a microscope (magnificatio X 30). The marginal gap was measured before and after ceramic application. The results were elaborated by descriptive statistical and two-way analysis of variance (ANOVA). The ANOVA revealed no significant difference between marginal gap before and after the ceramic application (p=5%). It was concluded that the porcelain application does not influence the marginal fit of copings, therefore the two marginal endings can be used with the electroforming system.

Keywords

• Electroforming. Crowns. Margin design. Marginal fit