The dual cure cements should not be used with light transmitting prostheses thicker than:
Dual-cure cements require mixing similar to that for the chemical-cure systems. Static mixing and trituration of capsules have largely replaced the need for hand mixing. 
Curing proceeds slowly until the cement is exposed to the curing light, at which point the cement hardens rapidly. These dual-cure cements should not be used with light-transmitting prostheses thicker than 2.5 mm; anything thicker than 2.5 mm should be bonded with chemical-cure cement. 
Removal of excess cement may be performed after seating or after waiting for a specific period as indicated in the manufacturer’s directions for use.

Ref: Phillip’s 12th edition page 330
1.0 mm
1.5 mm
2.0 mm
2.5 mm