Fracture resistance of five different metal framework designs for metal-ceramic restorations.
OBJECTIVE
This study evaluated fracture resistance of five different metal framework designs for metal-ceramic restorations.


METHODS
Twenty-five artificial crowns were fabricated with different degrees of facial metal reduction: metal collar (group 1), and 0, 0.5, 1, and 1.5 mm (groups 2 to 5, respectively). All of the crowns were thermocycled in two different baths of 5 and 60 degrees C for 20 seconds and had a dwell time of 10 seconds in a resting bath at 37 degrees C for 510 cycles. The artificial crowns were then subjected to vertical loading until fracture with a Shimadzu testing machine at a cross-head speed of 1 mm/min. The load at fracture was recorded.


RESULTS
There were no statistically significant differences between mean fracture strength of groups 1 and 2 or between groups 4 and 5. There were significant differences between group 3 and groups 1, 2, 4, and 5.


CONCLUSIONS
As the amount of metal reduction increased, the vertical fracture resistance decreased. Failure loads for all test groups exceeded normal biting forces.
Ulusoy
Mübin
M
Department of Prosthodontics, School of Dentistry, Ege University, Izmir, Turkey. ulusoyms@yahoo.com
Toksavul
Suna
S
D000704:Analysis of Variance; D001732:Bite Force; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D013816:Thermodynamics; D016474:Weight-Bearing
D016876:Metal Ceramic Alloys; D003776:Dental Porcelain