ABSTRACT
<p><b>OBJECTIVE</b>To compare the adaptation of porcelain fused-to-metal (PFM) restorations made from Ni-Cr alloy, precious alloy and galvanized forming copings after cementation and to provide a theory guidance for their application.</p><p><b>METHODS</b>Three kinds of crowns (Ni-Cr alloy, precious alloy and galvanized forming) were manufactured and cleaned by ultrasonic vibrate with alcoholic solution for 5 minutes, and cemented on their dies as their order. All the crowns were cemented by polycarboxylate zinc-cement and maintained 10 minutes. After coated in the center of methyl acrylic resins, all the samples were cut vertically along buccolingual direction. The cement thickness of PFM was measured by scanning electron microscope and the data were analyzed by multivariate ANOVA.</p><p><b>RESULTS</b>No significant difference was found between the cement thickness of precious alloy crown and galvanized forming crown (P>0.05), while both of these two kinds of crown had significant differences in cement thickness with Ni-Cr crown (P<0.05).</p><p><b>CONCLUSION</b>The adaptation of precious alloy crown and galvanized forming crown are superior to Ni-Cr crown.</p>
Subject(s)
Cementation , Crowns , Dental Cements , Dental Porcelain , Glass Ionomer Cements , MetalsABSTRACT
<p><b>OBJECTIVE</b>To compare the color differences of different metal bases and different opaque thickness, and evaluate the best thickness of opaque on different metal bases.</p><p><b>METHODS</b>Precious metal, gold sediment and Ni-Cr plates were prepared as bases, then opaque samples of 0.05, 0.1, 0.2, 0.3, 0.4 and 0.5 mm thickness were fabricated on such plates. Minolta chromatics meter CR-321 was used to examine the color properties of these samples, and deltaE was calculated to evaluate the color difference of the specimens.</p><p><b>RESULTS</b>For the restoration based on Ni-Cr and precious alloys, the color of restorations was not affected by the color of metal bases as the thickness of opaque reached 0.3 mm, and the chromatic value deltaE < 1.5 NBS. For the restoration based on gold sediment, the color of restoration was not affected by the color of metal as the thickness of opaque reached 0.1 mm, and the chromatic value deltaE < 1.5 NBS.</p><p><b>CONCLUSION</b>Different opaque thickness was necessary to obtain ideal color appearance in clinic. As the opaque thickness increased, the color of restoration based on Ni-Cr and noble metal increased but the color of restoration based on gold sediment decreased.</p>