Tooth does not posses the regenerative ability found in most other tissues there-fore once enamel dentin is lost as a result of caries, trauma or wear, will require crown to reestablish form and function, which will require tooth preparation, so careful attention should be given to all these procedures, such a way that the further procedures are made comfortable, the principles of tooth preparation can be divided into three categories Biologic considerations which affect the health of oral tissues mechanical considerations which affect the intergrity and durability of the restoration esthetic consideration which affects the appearence of the patient, all ceramic crowns are one of the estheticially pleasing restoration when comming under crowns the advantages of all ceramic crownsinclude its superior esthetics, its excellent translucency and its good tissue response, lack of metal substructe prevents the reduction of tooth needed when compared to metal ceramic crowns but lingual and proximal reduction is needed more, the disadvantage of all ceramic crown is the tendency to fracture is high when placed in especially stress areas and induvidual with grinding and clenching habbit.