Casting shrinkage of thin-walled castings. 1995

H Ogura
Junior College at Niigata, Nippon Dental University, Japan.

OBJECTIVE The casting shrinkage of thin-walled castings was measured using a tungsten die method. The thickness and the surface area of the casting were simulated to those of either partial veneer crowns or complete denture frameworks. Gold alloys were cast at two different pressures (0.35 and 0.49 MPa) and the shrinkage measurement was made at different locations on the castings to investigate the effect of these factors. RESULTS Both overall and local shrinkages were significantly influenced by size and casting pressure. These shrinkages were significantly lower for the denture-sized (DS) specimens than for the crown-sized (CS) specimens, and significantly decreased with the increase of the casting pressure. The effect of location on the local shrinkage significantly varied with the change of the other two factors, size and pressure. At the higher casting pressure, the DS specimens sustained a significantly smaller shrinkage at the margin than at the centre, whereas the CS specimens had a significantly smaller shrinkage at the centre than at the margin at the lower pressure. CONCLUSIONS The results suggest that the casting shrinkage of a thin-walled casting is influenced by the temperature gradient in the alloy and the resultant time difference in alloy solidification as well as the volume supply of the molten alloy in the mould.

UI MeSH Term Description Entries
D011312 Pressure A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed) Pressures
D003442 Crowns A prosthetic restoration that reproduces the entire surface anatomy of the visible natural crown of a tooth. It may be partial (covering three or more surfaces of a tooth) or complete (covering all surfaces). It is made of gold or other metal, porcelain, or resin. Dental Crowns,Crown, Dental,Crowns, Dental,Dental Crown,Crown
D003734 Dental Casting Investment Material from which the casting mold is made in the fabrication of gold or cobalt-chromium castings. (Boucher's Clinical Dental Terminology, 4th ed, p168) Casting Investment, Dental,Casting Investments, Dental,Dental Casting Investments,Investment, Dental Casting,Investments, Dental Casting
D003735 Dental Casting Technique The process of producing a form or impression made of metal or plaster using a mold. Casting Technic, Dental,Casting Technics, Dental,Casting Technique, Dental,Casting Techniques, Dental,Dental Casting Technic,Dental Casting Technics,Dental Casting Techniques,Technic, Dental Casting,Technics, Dental Casting,Technique, Dental Casting,Techniques, Dental Casting
D003765 Models, Dental Presentation devices used for patient education and technique training in dentistry. Dental Models,Dental Model,Model, Dental
D003801 Dental Veneers The use of a layer of tooth-colored material, usually porcelain or acrylic resin, applied to the surface of natural teeth, crowns, or pontics by fusion, cementation, or mechanical retention. Dental Laminates,Dental Laminate,Dental Veneer,Laminate, Dental,Laminates, Dental,Veneer, Dental,Veneers, Dental
D003819 Denture Bases The part of a denture that overlies the soft tissue and supports the supplied teeth and is supported in turn by abutment teeth or the residual alveolar ridge. It is usually made of resins or metal or their combination. Base, Denture,Bases, Denture,Denture Base
D003824 Denture, Complete A denture replacing all natural teeth and associated structures in both the maxilla and mandible. Complete Denture,Complete Dentures,Dentures, Complete
D006047 Gold Alloys Alloys that contain a high percentage of gold. They are used in restorative or prosthetic dentistry. Gold Alloy,Alloy, Gold,Alloys, Gold
D013499 Surface Properties Characteristics or attributes of the outer boundaries of objects, including molecules. Properties, Surface,Property, Surface,Surface Property

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