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Aim:The aim of this study was to evaluate the effect of recasting base metal alloy on the metal-ceramic bond strength. Materials and methods:A total of 60 test samples were prepared from new and recast nickel-chromium alloy and divided into six groups. In group A0, test samples were prepared from 100% new alloy. Groups A1, A2, A3, A4, and A5 were prepared from 50% new alloy and 50% casting remnants (sprue and buttons) of the previous group by weight. All these samples were coated with ceramic (IPS d.SIGN and Ivoclar-Vivadent), and samples were then subjected to three-point bending test to evaluate metal-ceramic bond strength. Results:The values were analyzed using one-way analysis of variance and Tukey's post hoc test. The mean bond strength of group A0 was higher than that of groups A1, A2, A3, A4, and A5. Conclusion:Metal-ceramic bond strength decreased significantly with multiple recastings.Clinical significance: Bond strength between metal and ceramic is a crucial factor for the clinical performance of metal-ceramic restorations. Recasting of alloys may affect the metal oxide layer composition and thickness of metal-ceramic interface, and thereby the metal-ceramic bond.

Maxillofacial prostheses for acquired defects have become more complex and sophisticated with advances in surgical, physical, and rehabilitative dentistry, but before planning, orofacial structures must be analyzed as to the specific cause and the consequent objectives of rehabilitation. Also retention of facial prostheses is very much challenging. Hence, we are presenting the fabrication of an interim prosthesis obturator and cheek prosthesis to restore the speech, help in deglutition and prevent drooling of saliva.

The aim of this study was to evaluate and compare shear bond strength of zirconia core to veneering porcelain after different methods of surface conditioning of the core. Materials and methods: 40 zirconia blocks were milled in the CAD/CAM system and divided into four groups (n=10). After sintering, Group A, control, no surface conditioning, group B specimens were subjected to air-borne particle abrasion with 110 µ aluminium oxide, Group C specimens were sandblasted with silica coated alumina particles. For Group D a mixture zirconia powder and adhesive were applied on the surface of the specimens before sintering. All these specimens were veneered with dimensions 3mm length, 5mm width and 3mm in height. Specimens were subjected to shear force and the shear bond strength was calculated. Fractured specimens were observed under scanning electron microscope. Results: The mean shear bond strength values in MPa were 40.06, 41.91, and 42.89, 47.24 for group A, B C and D respectively and statistically significant (p<0.05). Group D demonstrated higher shear bond strength than other groups. Scanning electron microscope evaluation showed cohesive fracture in the veneering porcelain in modified zirconia, while the other groups principally fractured at the core-veneer interface. Conclusion: Surface conditioning of zirconia core with zirconia powder slurry significantly improved the shear bond strength.

The study was coducted to evaluate and compare the wear behaviour of human enamel opposing three different newly introduced pressable all ceramic restorations. Materials and Methods: 45 freshly extracted human first premolar teeth were collected and divided into three groups of 15 each. The teeth were sectioned at CEJ and enamel specimens were mounted onto an acrylic wheel with 2 mm of buccal and lingual cusps exposed. 15 ceramic disks were prepared from each of three pressable ceramics. The enamel specimens and ceramic disks were subjected to wear under load of 100 N for 10000 cycles at 72 rpm. Enamel specimens were weighed before and after wear testing and observed under SEM for wear pattern. Results: The mean weight loss of Group C was greater than Group B followed by Group A. Pairwise comparision showed there was highly significant difference in weight loss among the groups. Conclusion: IPS e max press produced least wear followed by VITA PM9 and Ultra Will Ceram. IPS e max press produced least rough surface followed by VITA PM9 whereas Ultra Will Ceram produced roughest surface.