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Casting shrinkage of thin-walled castings
1Junior College at Niigata, Nippon Dental University, Japan.
Journal of Dentistry
|August 1, 1995
Summary
Casting shrinkage in dental restorations is reduced with higher casting pressure and larger specimen size. Denture-sized castings showed less shrinkage than crown-sized ones, especially at higher pressures.
Area of Science:
- Materials Science
- Biomaterials Engineering
- Dental Technology
Background:
- Casting shrinkage is a critical factor affecting the fit and accuracy of dental restorations.
- Understanding factors influencing shrinkage is essential for improving casting quality.
Purpose of the Study:
- To investigate the effects of specimen size and casting pressure on the casting shrinkage of thin-walled gold alloy castings.
- To analyze shrinkage variations at different locations within the castings.
Main Methods:
- Utilized a tungsten die method to measure casting shrinkage.
- Simulated dental casting dimensions for partial veneer crowns and complete denture frameworks.
- Castings were produced at two different pressures (0.35 and 0.49 MPa).
Main Results:
- Both overall and local casting shrinkages were significantly affected by specimen size and casting pressure.
- Denture-sized specimens exhibited lower shrinkage than crown-sized specimens.
- Increased casting pressure led to decreased shrinkage, with location-specific variations observed.
Conclusions:
- Casting shrinkage is influenced by temperature gradients, solidification time differences, and molten alloy volume supply.
- Optimizing casting pressure and considering specimen size are crucial for minimizing shrinkage in thin-walled castings.