ABSTRACT
OBJECTIVES: This study evaluated the marginal misfit and microleakage of cement-retained implant-supported crown copings. METHODS: Single crown structures were constructed with: (1) laser-sintered Co-Cr (LS); (2) vacuum-cast Co-Cr (CC) and (3) vacuum-cast Ni-Cr-Ti (CN). Samples of each alloy group were randomly luted in standard fashion onto machined titanium abutments using: (1) GC Fuji PLUS (FP); (2) Clearfil Esthetic Cement (CEC); (3) RelyX Unicem 2 Automix (RXU) and (4) DentoTemp (DT) (n=15 each). After 60 days of water ageing, vertical discrepancy was SEM-measured and cement microleakage was scored using a digital microscope. Misfit data were subjected to two-way ANOVA and Student-Newman-Keuls multiple comparisons tests. Kruskal-Wallis and Dunn's tests were run for microleakage analysis (α=0.05). RESULTS: Regardless of the cement type, LS samples exhibited the best fit, whilst CC and CN performed equally well. Despite the framework alloy and manufacturing technique, FP and DT provide comparably better fit and greater microleakage scores than did CEC and RXU, which showed no differences. CONCLUSIONS: DMLS of Co-Cr may be a reliable alternative to the casting of base metal alloys to obtain well-fitted implant-supported crowns, although all the groups tested were within the clinically acceptable range of vertical discrepancy. No strong correlations were found between misfit and microleakage. Notwithstanding the framework alloy, definitive resin-modified glass-ionomer (FP) and temporary acrylic/urethane-based (DT) cements demonstrated comparably better marginal fit and greater microleakage scores than did 10-methacryloxydecyl-dihydrogen phosphate-based (CEC) and self-adhesive (RXU) dual-cure resin agents.
