Abstract
Statement of the Problem. Investigators suggest that metals should be finished in 1 direction before porcelain
application to minimize metal irregularities and trapped contaminants. These irregularities
are thought to be focal points for porosity and crack propagation. Purpose. This study investigated the influence of metal finishing and sandblasting on (1)
porosity production at the porcelain-metal interface, and (2) porcelain-metal beam
failure load. Material and Methods. Eighty cast metal samples were divided into 4 test groups: (A) bidirectional finish/sandblasting;
(B) unidirectional finish/sandblasting (C) bidirectional finish only; and (D) unidirectional
finish only. The porcelain applied was 1.5 mm thick. Samples were sectioned longitudinally.
Half of the samples were subjected to a 3-point flexural test. The remaining samples
were sectioned into 4 slices and were examined with a light microscope (×500). Number
and diameter of porosities at the metal-porcelain interface were recorded. Results. Mean loads at failure (lbs) were as follows: A, 11.1 ± 1.3 (5.03 ± 0.58 Kg); B, 11.2
± 1.7 (5.08 ± 0.77 Kg); C, 4.0 ± 1.8 (1.81 ± 0.81 Kg); and D, 5.0 ± 2.1 (2.26 ± 0.95
Kg). Groups A and B were significantly different from groups C and D (P<.0001). Nonsandblasted samples (C and D) exhibited a separation at the ceramometal
interface, which prevented quantification of porosity size and number. Average interface
porosity sizes (μm) (A, 8.99 ± 1.92; B, 10.03 ± 1.86) showed no significant difference.
The mean interface porosity number (A, 62.3 ± 16.02; B, 67.4 ± 10.01) showed no significant
difference. Conclusion. Direction of metal finishing did not affect the porosity number and size at the ceramometal
interface or the beam failure loads. Sandblasting increased the beam failure loads.
Nonsandblasted samples showed detachment of the porcelain from the metal. (J Prosthet
Dent 2000;84:309-17.)
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Article info
Footnotes
*Funded by the American Academy of Fixed Prosthodontics 1998 Tylman Research Grant. Awarded the 2nd Place Tylman Award in February 1999.
**Reprint requests to: Dr Carlo Ercoli, Division of Prosthodontics, University of Rochester Eastman Dental Center, 625 Elmwood Ave, Rochester, NY 14620, Fax: (716) 244-8772, E-mail: [email protected]
★J Prosthet Dent 2000;84:309-17
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Copyright
© 2000 Editorial Council of The Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.
