J Adv Prosthodont.  2011 Sep;3(3):113-118. 10.4047/jap.2011.3.3.113.

Alternate metal framework designs for the metal ceramic prosthesis to enhance the esthetics

• Vernekar N
• Jagadish P
• Diwakar S
• Nadgir R
• Krishnarao MR

• KMID: 2118118
• DOI: http://doi.org/10.4047/jap.2011.3.3.113

Abstract

PURPOSE
The objective of the present study was to evaluate the effect of five different metal framework designs on the fracture resistance of the metal-ceramic restorations.
MATERIALS AND METHODS
For the purpose of this study, the central incisor tooth was prepared, and the metal analogue of it and a master die were fabricated. The counter die with the 0.5 mm clearance was used for fabricating the wax patterns for the metal copings. The metal copings with five different metal framework designs were designed from Group 1 to 5. Group 1 with the metal collar, Group 2, 3, 4 and 5 with 0 mm, 0.5 mm, 1 mm and 1.5 mm cervical metal reduction respectively were fabricated. Total of fifty metal ceramic crown samples were fabricated. The fracture resistance was evaluated with the Universal Testing Machine (Instron model No 1011, UK). The basic data was subjected to statistical analysis by ANOVA and Student's t-test.
RESULTS
Results revealed that the fracture resistance ranged from 651.2 to 993.6 N/m2. Group 1 showed the maximum and Group 5 showed the least value.
CONCLUSION
The maximum load required to fracture the test specimens even in the groups without the metal collar was found to be exceeding the occlusal forces. Therefore, the metal frameworks with 0.5 mm and 1 mm short of the finish line are recommended for anterior metal ceramic restoration having adequate fracture resistance.

Keyword

Metal-ceramic crown; Fracture resistance; Collarless metal ceramic restoration

MeSH Terms

Bite Force
Ceramics
Collodion
Crowns
Esthetics
Incisor
Organothiophosphorus Compounds
Prostheses and Implants
Tooth
Ceramics
Collodion
Organothiophosphorus Compounds

Figure

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  Fig. 1 Metal die, counter die, metal rings and silicone mold used for fabricating the test specimens.

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  Fig. 2 Traveling microscope.

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  Fig. 3 Completed metal-ceramic restoration specimens.

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  Fig. 4 Instron universal testing machine used.

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  Fig. 5 Samples counted on Instron testing machine.

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  Fig. 6 Fractured test specimens.

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