Send to

Choose Destination
J Oral Rehabil. 2006 Jul;33(7):520-8.

Thin-wall ceramic CAD/CAM crown copings: strength and fracture pattern.

Author information

Department of Preventive Dentistry, Periodontology and Cariology, Center for Dental and Oral Medicine, Division of Aesthetic and Computer Restorations, University of Zurich, Zurich, Switzerland.


The strength and fracture pattern of posterior CAD/CAM-generated crown copings with 0.4 mm wall thickness were evaluated in vitro hypothesizing that fracture resistance of YTZP-zirconia copings might be independent of mode of cementation whether resin-bonded or cemented because of the high strength of YTZP-zirconia. Two sets of copings (n = 15) each were fabricated using CEREC inLab CAD/CAM from (i) lithiumdisilicate glass-ceramic, (ii) infiltration ceramic as controls and (iii) YTZP-zirconia. Copings (n = 15) of ceramics (i), (ii) and (iii) each were (a) zinc-phosphate cemented, (b) adhesively seated on resin-based composite dies and loaded until fracture. Load (N) data was analysed using anova and Scheffé tests. Crack pattern was evaluated on additional three sample cross-sections for each group at fracture-start. Radial cracks originated early at the cementation interfaces and cone cracks were observed finally at the loading sites. Mean load (N) values (+/-s.d.) of A-copings at fracture-start/-end (i) 804 +/- 195/862 +/- 162, (ii) 923 +/- 180/975 +/- 147, (iii) 697 +/- 110/1607 +/- 145, were all significantly (P < 0.01) lower when compared with their B-crown coping analogs (i) 1183 +/- 318/1919 +/- 326, (ii) 1621 +/- 165/1820 +/- 211, (iii) 731 +/- 115/1973 +/- 287 except for A3 and B3 at fracture-start. This confirmed our hypothesis at fracture-start (P > 0.05) but rejected it at fracture-end (P < 0.01). The A3 fracture-end data, even if significantly (P < 0.01) lower, came close to the B3 values by 18%. A3 was significantly (P < 0.001) stronger by 86/74% than A1/A2 at fracture-end. The data indicates that YTZP-zirconia copings have the potential to provide support for all-ceramic core crowns, which may be adequate for non-adhesive cementation.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center