[ evaluation of the effect of two preparation design: shoulder and heavy chamfer in IPS e.max press restorations - in vitro]

ABSTRACT

Marginal integrity in all ceramic restorations is one of the important elements of the success rate. According to the importance of design preparation in the marginal integrity, in this in-vitro study, decided to compare the marginal integrity between 2 different types of the marginal preparation shoulder and classic chamfer in IPS e.max press restoration. This experimental research has been done in vitro with the single blind technique. One standard die with 7mm height, 5mm diameter was prepared by the milling machine. the preparation design consists half shoulder 90 degree and in the other half classic chamfer, with 1mm depth in both of them and 10 degree tapering and then crowns were made of IPS e.max press and after cementation, were ground at the buccolingually direction. Then they were coated by gold and observed under SEM. The data assessed by T-Test. A difference between 2 types of marginal preparation was significant [p<0.05]. Marginal gap in shoulder preparation was 15.45 +/- 0.79 and in classic chamfer site was 13.78 +/- 0.52. The marginal fitness in the classic chamfer preparation was better than shoulder preparation in all ceramic restorations