Mechanical properties of  Y-TZP ceramics – a comparison of quality

Objective: Y-TZP ceramics are widely used in dentistry. Mostly interesting parameters for comparison of quality are bending strength, Weibull modulus, fracture toughness and Weibull strength. Defect size and distribution, surface quality and stability are essential for a long lifetime of application. The aim of this work is to compare 8 different commercial available Y-TZP ceramic for CAD CAM production of any dental device. Method: From a CAD CAM block of each of the chosen ceramics a part would be cut and than 30 specimens as recommended by ISO 6872 would be prepared. The specimens were sintered at 1530°C for 2h using a Vita Zyrcomat. All specimens were polished and broken in a 3-point bending set up using a Zwick 010 with a cross head speed of 1mm/min. Result:

Ceramic	σb [MPa]	m	σW [MPa]
Bruxzir	947 ± 186	6,93	1026
Copran	915 ± 241	6,91	1010
Denseo	1251 ± 132	7,18	1322
Doceram	986 ± 130	6,93	1026
Metoxit	606 ± 53	6,44	632
Microceram	1129 ± 141	7,08	1193
Zzstar intense	994 ± 100	6,95	1046
ZirkonZahn	1114 ± 126	7,06	1175

 The values in the table show a big variation as well in strength as in the Weibull modulus.

Conclusion: These observed values demonstrate a big difference to the data published by the companies in their data sheets, where the bending strength is given by 1200MPa and m is higher as 11. It seems to be necessary to have access to independent tests of a broad row of Y-TZP ceramics for a reliable comparison of various ceramic blanks on the market.