IN-VIVO MARGINAL ADAPTATION OF CAST CROWNS LUTED WITH DIFFERENT CEMENTS

Large marginal crown discrepancies are deleterious. Although previous studies have examined casting seating in vitro, few have evaluated the effects of different luting cements on in vivo seating. Hence this in vivo study compared marginal discrepancies created by different cemen ts on cast crowns. Tooth preparations were completed according to acce ptable procedures on previously intact human molars that were severely periodontally compromised and scheduled for extraction. Castings were made by conventional techniques. The castings were randomly assigned to the following luting agents: zinc phosphate cement, resin-modified glass-ionomer cement, and the same resin-modified glass-ionomer cement with a dentinal bonding agent. After 6 months the teeth were carefull y extracted, embedded, and sectioned, and vertical and horizontal disc repancies were measured. Analysis of variance revealed that all cement s resulted in similar discrepancies. Vertical discrepancies were consi derably greater than horizontal discrepancies, and the distributions o f marginal discrepancies were skewed towards upper ranges.