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Abstract
The aim of this in-vitro study was to assess the effect of finish line steepness (1 and 3 mm) and construction technique ( machinable and pressable ) on the vertical marginal gap distance of the IPS e.max ceramic copings In this study a total of 54 IPS e.max ceramic copings were constructed and divided according to construction technique into two main groups: group I (n=14): Machinable all ceramic copings (IPS e.max CAD) group II (n=40): Heat pressed all ceramic copings (IPS e.max Press) Each group was further subdivided into two subgroups according to different finish line steepness: Subgroup 1 : 1-mm finish line steepness Subgroup 2 : 3-mm finish line steepness Two ivory upper central incisors with same dimensions were selected, mounted in a stone base and prepared to receive full coverage all ceramic crowns with the two different finish line steepness using dental milling surveyor. Two nickel chromium dies with two different finish line steepnesses were then fabricated by duplication from the two prepared ivory upper central incisors. Machinable and pressable IPS e.max ceramic copings were constructed on these metal dies according to the manufacturer instruction following standardized protocol. For all samples, vertical marginal gap distance was measured at three selected points on the middle third of each surface of the die. The marginal area were photographed under magnification of x40 with digital camera attached to a stereomicroscope which was coupled to a computerized Quantitative analysis system, by means of software. The vertical marginal gap distance was measured in micrometers (æm). Each measurement was repeated three times, with all measurements being performed by a single investigator. Data were collected, tabulated and statistically analyzed