Microleakage assessment at the interface between a Ni-Cr based alloy and three ceromers (Belleglass, Signum, Gradia)

This study assessed cervical microleakage between a Ni-Cr alloy and 3 indirect polymeric veneering materials. Methods & Materials: In this experimental study, twenty one metalic frameworks (copings) were obtained by fabrication 0.5 mm calibrated wax patterns on a master cast abutment. The wax patterns were provided with 0.4 mm beaded retention on the veneering surfaces and cast in a Ni-Cr based alloy used for fixed partial dentures. The Ni-Cr copings were divided equally into 3 groups, 7 samples in each group, and veneered with 3 polymeric materials (Belleglass, Signum, Gradia). Three chemical conditioning systems (metal prep, retention flow, GC metal primer II) were used with the respective veneering system recommended by the manufacturer no control group was created. After, 2 weeks of storage in distilled water at 37 ºC, 2000 cycles at 5-55ºC, and 24 hours of storage in 0.5% basic fuchsine, specimens were embedded in clear liquid casting resin and sectioned along a perpendicular cervico-incisal plane through the middle of cervical collar. The surfaces of the resulting sections were examined in the cervical area with a dimensional microscope to detect dye penetration. Scores were compared and analysed with the use of Kruskal-wallis test. Signum was associated with the highest microleakage scores (1.4286±0.5345) and the least microleakage at the interface was produced by Belleglass (0.4236±0.07868), followed by Gradia (0.8571±0.3779). Only the difference between Belleglass and Signum was significant (P=0.024). Within the limitation of this in vitro study, the extent of cervical microleakge between the coping and veneer depended on the particular polymeric material used for veneering. The extremes of the study were Belleglass and Signum (respectively lowest and highest leakage scores).