Marginal fit and surface roughness of crowns made with an accelerated casting technique.
BACKGROUND
Conventional investing and casting techniques following the manufactures' recommendations are time-consuming. Accelerated casting techniques have been reported, but their accuracy has not been adequately studied for complete crown castings.


OBJECTIVE
This study evaluated the marginal fit and surface roughness of complete crowns made with a conventional and an accelerated casting technique.


METHODS
Part I of the study determined the mean time interval required for each investment to reach its maximum exothermic setting reaction temperature. Part II determined the marginal discrepancy of standardized complete crowns cast in a high noble metal ceramic alloy, with the use of four phosphate-bonded investments. A conventional technique (as recommended by the manufacturer) was compared with an accelerated technique that used 13- to 17-minute bench set time (as determined in part 1 for each investment)_ and 15-minute wax elimination cycle in a 815 degrees C (1500 degrees F) preheated furnace. Part III evaluated the surface roughness of castings made with the same techniques as in part II.


RESULTS
For the marginal discrepancy and surface roughness, crowns fabricated with the accelerated casting technique were not significantly (P > 0.05) different from those fabricated with the conventional technique.


CONCLUSIONS
The accelerated casting technique described in this study could be a vital alternative to the time-consuming conventional techniques.
Konstantoulakis
E
E
Texas A&M University System--Baylor College of Dentistry, Dallas, USA.
Nakajima
H
H
Woody
R D
RD
Miller
A W
AW
D003442:Crowns; D003734:Dental Casting Investment; D003735:Dental Casting Technique; D018772:Dental Marginal Adaptation; D006801:Humans; D017755:Prosthesis Fitting; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
D003734:Dental Casting Investment