ABSTRACT
PURPOSE: This study was aimed to compare the margin and internal fitness of 3-unit zirconia bridge cores fabricated by several CAD/CAM systems using replica technique. MATERIALS AND METHODS: Three unit-bridge models in which upper canine and upper second premolar were used as abutments and upper first premolar was missed, were fabricated. Fourty models were classified into 4 groups (Cerasys(R) (Group C), Dentaim(R) (Group D), KaVo Everest(R) (Group K), Lava(TM)(Group L)), and zirconia cores were fabricated by each company. Sixteen points were measured on each abutment by replica technique. Statistical analysis was accomplished with two way ANOVA and Dunnett T3 (alpha=.05). RESULTS: In most systems, there was a larger gap on inter margin than outer margin. In the Group K, overall fitness was excellent, but the incisal gap was very large. In the Group C, marginal gap was significantly larger than Group K, but overall internal gap was uniform (P<.05). The axial gap was under 100 microm in all system. The difference between internal and external gap was small on Group L and C. However, internal gap was significantly larger than external gap in Group D (P<.05). The fitness of canine was better than second premolar among abutments (P<.05). CONCLUSION: The marginal and internal gap was within the clinically allowed range in all of the three systems. There was a larger gap on second premolar than canine on internal and marginal surface. In most systems, there was a larger gap on occlusal surface than axial surface.