2. To test the hypothesis that a reinforced glass ionomer cement (ProTec CEM, Ivoclar, Vivadent), when used to cement core ceramic crowns in posterior FPDs, will be associated with significantly less marginal quality, but similar fracture resistance of the ceramic crowns compared with the marginal quality associated with a dual cure resin cement (Variolink® II, Ivoclar Vivadent AG, Schaan, Liechtenstein).