Influence of polyurethane resin dies on the fit and adaptation of full veneer crowns.
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Date
2015-01
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Abstract
Context: Polyurethane resin is a possible alternative to type IV dental stone for fabrication of
indirect restorations however its dimensional accuracy is questionable.
Aim: The aim was to investigate the dimensional accuracy of silica filled polyurethane resin
die material by evaluating the marginal fit and adaptation of indirect gold castings.
Settings and Design: Experimental, in vitro study.
Materials and Methods: Totally 40 copper plated replicas of a nickel chrome master die analogous
to a veneer gold crown preparation were made and impressions recorded using polyvinylsiloxane
material. Twenty impressions were poured in type IV dental stone (control group (Vel‑mix,
Kerr, UK) and the remaining (n = 20) in silica filled polyurethane die material (test group) (Alpha
Die MF, CA, USA). Gold castings were fabricated for each die using standardized techniques. The
castings were seated on their respective copper plated dies, embedded in resin and sectioned.
The specimens were analyzed by measuring marginal opening and the area beneath the casting
at a ×63 magnification and using image analysis software.
Statistical Analysis Used: Data were analyzed using a Student’s t‑test.
Results: No significant difference was observed between the experimental groups (P > 0.05).
The mean marginal opening for type IV, dental stone and polyurethane resin, was
57 ± 22.6 μm and 63.47 ± 27.1 μm, respectively. Stone displayed a smaller area beneath the
casting (31581 ± 16297 μm2) as compared to polyurethane resin (35003 ± 23039 μm2).
Conclusions: The fit and adaptation of indirect gold castings made on polyurethane and type IV
dental stone dies were comparable.
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Keywords
Crown, die material, indirect casting, marginal fit, polyurethane resin
Citation
Lillywhite Graeme RR, Vohra Fahim. Influence of polyurethane resin dies on the fit and adaptation of full veneer crowns. Indian Journal of Dental Research. 2015 Jan-Feb; 26(1): 72-76.