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| Titel: |
Fracture toughness and durability of chemically or thermally tempered metal-ceramic porcelain |
| Auteur: |
Hae-Hyoung Lee Masayuki Kon Kenzo Asaoka |
| Verschenen in: |
Bio-medical materials and engineering |
| Paginering: | Jaargang 9 (2001) nr. 3 pagina's 135-143 |
| Jaar: |
2001-04-01 |
| Inhoud: |
Thermocycling and water storage effects on fracture toughness (K_\mathrm{IC}) of chemically or thermally tempered metal-ceramic disks were investigated to evaluate the durability of tempering effects with regard to oral aqueous environment. Metal-ceramic disks (\varnothing10 mm \times 2.0 mm) consisting of opaque porcelain (0.2 mm thick), body porcelain (1.3 mm) and Ni-Cr-Be alloy (0.5 mm) were prepared and the porcelain surfaces were polished with 1-\mum diamond paste. The disks were subjected to ion exchange (potassium or rubidium) or thermal tempering treatments, then with the as-polished or further annealed disks, thermocycled for 8000, 15,000, and 22,000 cycles between 5^\circC and 60^\circC or stored in water at 37^\circC for 33 days. After aging, K_\mathrm{IC} values of disks were determined by a Vickers indentation technique. Statistical analyses indicated that the K_\mathrm{IC} values of ion-exchanged and annealed disks were not significantly affected by the limited number of cycles and water storage, while the thermally tempered and untreated disks revealed a significant decrease in mean K_\mathrm{IC} from even 8000 cycles and after storage. However, there was no significant difference between thermocycling and water-storage effects on mean K_\mathrm{IC} of all surface treatment groups. Results indicate that chemical tempering (ion exchange) produced more durable residual stresses than does thermal tempering for metal-ceramic restorations. A low-thermal load only was unlikely to affect the apparent fracture toughness of porcelain. |
| Uitgever: |
IOS Press |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 2 van 7 gevonden artikelen
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