Impact of multiple firings on fracture load of veneered zirconia restorations.

Hensel, Justine; Reise, Michael; Liebermann, Anja; Buser, Ramona; Stawarczyk, Bogna (2022). Impact of multiple firings on fracture load of veneered zirconia restorations. Journal of the mechanical behavior of biomedical materials, 130, p. 105213. Elsevier 10.1016/j.jmbbm.2022.105213

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This investigation evaluated the impact of multiple firings during the veneering process of anterior all-ceramic restorations on the fracture load (FL) of zirconia crowns veneered with different ceramics (ZRT, ZRO, HFZ, STR).


All-ceramic crowns with anatomically reduced zirconia frameworks were prepared using four different veneering ceramics (N = 192/n = 48 per veneering ceramic). The crowns were fired 2 and 10 times. Half of them were thermocycled (5000 cycles, 5 °C/55 °C, 20s). FL using Voss shear test was measured. Data was analyzed using ANOVA with partial eta squared and post-hoc Scheffé-test as well as t-test and Weibull analysis.


Regarding FL, greatest differences were among the number of firings (p<0.001, ηp2 = 0.369). FL was not influenced by the interaction of both number of firings and aging level (p = 0.231) and the interaction of number of firings and veneering ceramic (p = 0.222). Differences were found comparing FL values of ZRT and STR (p<0.001) and of HFZ and STR (p<0.001). No differences occurred among the veneering ceramics after 2 (p = 0.430) and after 10 firings (p = 0.057) in respect to initial FL. For all initially tested veneering ceramics, FL showed higher values after 10 firings (p≤0.001-0.014). When aged, ZRO, HFZ, and STR also provided higher FL values after 10 firings (p≤0.001). For ZRT, FL values differed between initial and aged testing after 2 firings (p = 0.001) with aged specimens providing higher FL values. After 10 firings, none of the veneering ceramics showed differences regarding FL values between initial and aged testing. Weibull modulus was higher for ZRT specimens after 10 firings when tested initially (m = 10.1) and for aged ZRT specimens after 2 firings (m = 11.1). Failures occurred either with chipping of the veneer or total fracture.


Veneered zirconia restorations tested presented higher FL after 10 firings compared to 2 firings. Aging via thermocycling showed a positive effect on the FL.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > School of Dental Medicine > Department of Reconstructive Dentistry and Gerodontology

UniBE Contributor:

Buser, Ramona








Pubmed Import

Date Deposited:

07 Apr 2022 09:51

Last Modified:

05 Dec 2022 16:18

Publisher DOI:


PubMed ID:


Uncontrolled Keywords:

All-ceramic restoration Chipping Fracture load Leucite ceramic Multiple firings Thermal properties Veneering ceramics Zirconia




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