Methods: 60 customized implant abutments (CARES) for maxillary right central incisor made of titanium (Ti) and zirconia (Zr) (n=30 per group) were fabricated for an internal connection implant system. All-ceramics crowns were fabricated for their corresponding abutments using the following systems (n=10 per group): a) monolithic CAD/CAM lithium disilicate (MLD; IPS e.max CAD), b) pressed lithium disilicate (PLD; IPS e.max Press), c) yttrium stabilized tetragonal zirconia polycrystal (YTZP; IPS e.max ZirCad). The frameworks of both PLD and YTZP systems were veneered with fluorapatite-based ceramic (IPS e.max Ceram).The crowns were adhesively cemented (Multilink Implant) to their implants abutments. The absolute marginal discrepancy of the crowns was measured before and after cementation using Scanning Electronic Microscopy (SEM). Data were analyzed, using two-way repeated measures ANOVA and Tukey post-hoc test (α =0.05).
Results: Marginal discrepancy values were significantly affected by the all-ceramic crown systems (p=0.0001) before and after cementation (p=0.0001) but the abutment material (p=0.120) did not significantly affect the results. YTZP crowns on both Ti and Zr abutments presented the lowest mean marginal discrepancies before (52.1±17 - 56.2±11 μm) and after cementation (98.7±17 - 101.8±16 μm) (p<0.05). Before cementation, MLD crown system (75.2±12 - 77.5±13 μm) showed significantly higher mean marginal openings compared to manually veneered ones on both Ti and Zr abutments (52.1±17 - 69.7±8 μm) (p<0.05). After cementation, both Ti and Zr abutments in combination with MLD crowns (113.5±12 - 118.3±14 μm) presented significantly higher values than with manually veneered ones (98.7±17 - 109.4±9 μm) (p<0.05).
Conclusions: Manually veneered zirconia demonstrated more favourable marginal fit on both titanium and zirconia implant abutments before and after cementation compared to those of monolithic CAD/CAM lithium disilicate and manually veneered pressed lithium disilicate.