US EPA

1669103 

Journal Article 

Effect of airborne-particle abrasion and mechanico-thermal cycling on the flexural strength of glass ceramic fused to gold or cobalt-chromium alloy 

Oliveira de Vasconcellos, LG; Silva, LH; Reis de Vasconcellos, LM; Balducci, I; Takahashi, FE; Bottino, MA 

2011 

Yes 

Journal of Prosthodontics
ISSN: 1059-941X 

20 

7 

553-560 

English 

22003831 

10.1111/j.1532-849X.2011.00761.x 

WOS:000296841000009 

PURPOSE: To evaluate the effect of airborne-particle abrasion and mechanico-thermal cycling on the flexural strength of a ceramic fused to cobalt-chromium alloy or gold alloy.

MATERIALS AND METHODS: Metallic bars (n = 120) were made (25 mm × 3 mm × 0.5 mm): 60 with gold alloy and 60 with Co-Cr. At the central area of the bars (8 mm × 3 mm), a layer of opaque ceramic and then two layers of glass ceramic (Vita VM13, Vita Zahnfabrick) were fired onto it (thickness: 1 mm). Ten specimens from each alloy group were randomly allocated to a surface treatment [(tungsten bur or air-particle abrasion (APA) with Al(2) O(3) at 10 mm or 20 mm away)] and mechanico-thermal cycling (no cycling or mechanically loaded 20,000 cycles; 10 N distilled water at 37°C and then thermocycled 3000 cycles; 5°C to 55°C, dwell time 30 seconds) combination. Those specimens that did not undergo mechanico-thermal cycling were stored in water (37°C) for 24 hours. Bond strength was measured using a three-point bend test, according to ISO 9693. After the flexural strength test, failure types were noted. The data were analyzed using three factor-ANOVA and Tukey's test (α= 0.05).

RESULTS: There were no significant differences between the flexural bond strength of gold and Co-Cr groups (42.64 ± 8.25 and 43.39 ± 10.89 MPa, respectively). APA 10 and 20 mm away surface treatment (45.86 ± 9.31 and 46.38 ± 8.89 MPa, respectively) had similar mean flexural strength values, and both had significantly higher bond strength than tungsten bur treatment (36.81 ± 7.60 MPa). Mechanico-thermal cycling decreased the mean flexural strength values significantly for all six alloy-surface treatment combinations tested when compared to the control groups. The failure type was adhesive in the metal/ceramic interface for specimens surface treated only with the tungsten bur, and mixed for specimens surface treated with APA 10 and 20 mm.

CONCLUSIONS: Considering the levels adopted in this study, the alloy did not affect the bond strength; APA with Al(2) O(3) at 10 and 20 mm improved the flexural bond strength between ceramics and alloys used, and the mechanico-thermal cycling of metal-ceramic specimens resulted in a decrease of bond strength. 

Dental materials; airborne-particle abrasion; mechanical and thermal-cycling; chromium alloy; gold alloy; surface treatment; metal/ceramic joint