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[Evaluation of marginal adaptation of three different copings of metal-ceramic crowns]
Mei Xu1, Fan Yang, Ren-fei Wang
1Department of VIP, Zhejiang Chinese Medical University. Hangzhou, Zhejiang Province, China. lilyxumei@qq.com
Purpose:
To evaluate the marginal adaptation of three different copings of metal ceramic crowns cast in high golden, cobalt-chrome and nickel-chrome alloy.
Methods:
Thirty working dies were created from a single master die and used to fabricate thirty copings in each as the following groups: A(high golden alloy, n=10), B(cobalt-chrome alloy, n=10) and C(nickel-chrome alloy, n=10). All the metal copings were fabricated using the conventional lost wax casting technique. The restorations were seated on the master die, and high-resolution digital photographs were made of the marginal area on all four sides. The vertical marginal gap was then measured using a calibrated digital software program. One-way ANOVA and LSD tests were used to determine the differences using SPSS11.5 software package.
Results:
The mean marginal gaps were group A:(72.9±29.3)μm; group B(85.9±33.0)μm and group C(94.1±44.9)μm. There was significant difference among three groups(P(AB)<0.01,P(AC)<0.001,P(BC)<0.05).
Conclusions:
The marginal gaps of three different metal copings are all clinical acceptable. The high golden copings resulted in smaller marginal gaps than either cobalt-chrome or nickel-chrome copings.
