الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
1- A metal definitive die was duplicated from the readymade prepared tooth to be axisymmetric with a profile identical to an all-ceramic crown preparation on a mandibular first molar.
2- Twenty duplicated dies were fabricated in a high filler content resin material to replicate the definitive die, twenty impressions were made by using addition cured duplicating silicone impression material (negative replica).
3- Epoxy resin materials were prepared and poured in each impression to produce twenty dies having standardized dimensions (positive replica).
4- The root portion of the prepared teeth were embedded in acrylic resin, and they randomly allocated into two equal groups (I and II).Each group received ten crowns of different all ceramic systems.
5- Group I, ten IPS e.max press crowns were produced in the laboratory by hot-press system, a wax build up, investing preheating, pressing and divesting, finishing and veneering processes were carried out.
6- Group II, ten In-ceram zirconia were produced in the laboratory through conventional firing that involved slip-casting and glass-infiltration. A refractory dies were duplicated from the epoxy resin dies, application of the slip, sintering firing of the slip-cores, then glass infiltrated, glass infiltration firing, veneering, finishing and glazing were carried out.
7- All crowns were adhesively cemented on their respective dies using universal composite resin-bonded cement (Multilink Speed Automix).
8- All specimens of each group were loaded until fracture using the universal testing machine to record fracture resistance of each ceramic crown.
9- Fractured crowns were recovered from the dies, and the selected fractured surfaces were prepared for examination by gold coating. Scanning electron microscopy were used to determine the type of failure origin then statistical analysis was carried out.
10- The results showed no significant difference between IPS e.max press and conventionally fired In-ceram zirconia crowns in the fracture resistance. Also there was no significant difference in the origin of failure between the two groups.