Predictable casting for dimensional shrinkage of fast-cast post-and-cores.
BACKGROUND
Prior investigations into dimensional shrinkage of fast-cast post-and-cores resulted in variable dimensions. There is a need for consistent shrinkage of cast post-and-cores to reduce or eliminate lateral stresses on the remaining tooth structure.


OBJECTIVE
The purpose of this research was to find a method of casting post-and-cores that would result in consistent shrinkage.


METHODS
A total of 45 methyl methacrylate post-and-core patterns, 10 mm long, were fabricated from a standardized steel block. Three methods were used to cast the post-and-core. Investment materials used were Fast Fire 15 (Whip Mix Corp, Louisville, KY, USA) and Beauty Cast gypsum (Whip Mix Corp). Three groups of sample post and core patterns were cast, varying the investment material used and the burnout time.


RESULTS
Results show a statistical significance between the investment materials (p<0.05). The accelerated technique produced the most consistent results, and all samples had shrinkage of the casting.


CONCLUSIONS
The use of a phosphate investment with an accelerated technique can produce consistent and predictable shrinkage of cast post-and-cores.
Pa
P
Hansen
D003735:Dental Casting Technique; D006801:Humans; D011176:Post and Core Technique; D012117:Resins, Synthetic
D012117:Resins, Synthetic