In addition to proper marginal fit, the following should be taken into consideration:
We recommend that you do not use iron-containing hemostatic liquids with translucent all-ceramic crowns. A grayish tint may develop underneath the translucent restoration a few weeks after cementation. Do not use ferrous liquids at the impression appointment or seating appointment.
Hydrogen peroxide is a strong oxidizing agent that decomposes chemical initiating systems. Hydrogen peroxide is not easily removed from the tooth surface by a water spray. Typically, Amine and Peroxide are the two basic chemicals that make up a base and catalyst reaction in dental cements. The use of Hydrogen Peroxide should generally be avoided with all resin cements.
Contamination from saliva and crevicular fluids can be a major cause of discoloration. Use of a rubber dam, when possible, should be considered.