Marginal fit of restorations before and after cementation in vivo

Triturated luting cements provide convenient clinical handling. This study clinically evaluated the influence of two trituration capsule cement systems on the marginal fit of inner copings for telescoping crowns. Using a randomized parallel design, one coping was cemented using zinc phosphate cement (Phosphacap) and one using a glass-ionomer cement (Ketac-Cem Maxicap) for each of 12 patients. A blind examination of the marginal fit of the restorations was made before and after cementation using the replica technique and a scanning electron microscope. The mean marginal discrepancies for all cast copings were approximately 30 microns (median 23 microns) before cementation. They increased significantly after cementation to 86 microns (median 63 microns) in the zinc phosphate cement copings but to only to 47 microns (median 44 microns) in the glass-ionomer cement copings.