Fatigue resistance of monolithic strength-gradient zirconia materials.

Schönhoff, Lisa Marie; Lümkemann, Nina; Buser, Ramona; Hampe, Rüdiger; Stawarczyk, Bogna (2021). Fatigue resistance of monolithic strength-gradient zirconia materials. Journal of the mechanical behavior of biomedical materials, 119, p. 104504. Elsevier 10.1016/j.jmbbm.2021.104504

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PURPOSE

Evaluation of the effect of three different dynamic fatigue protocols on the fracture resistance of two monolithic strength-gradient zirconia materials.

MATERIALS AND METHODS

A total of 240 specimens (3 × 4 × 45 mm) was milled from two different layers (incisal and middle) of two types of strength-gradient zirconia blanks (IPS e. max ZirCAD MT Multi A2 vs. IPS e. max ZirCAD Prime A2), resulting in 60 specimens per material and layer group (IPS e. max ZirCAD MT Multi A2: incisal (MI), middle (MM); IPS e. max ZirCAD Prime A2: incisal (PI), middle (PM)). Each group was divided into one static (n = 15) and three dynamic fatigue protocols (N = 45, n = 15): i. 50 N increase every 5000 cycles ii. Increase by 5% of static fracture load every 5000 cycles iii. 10 N increase every 1000 cycles until facture. All specimens were loaded until facture in CeraTest 2 k. Kaplan-Meier, Log-Rank and Chi-squared-test as well as Weibull statistics were performed. A fractographic analysis was performed. The specimens were classified according to the number of crack origins and evaluated using the Ciba-Geigy table.

RESULTS

With regard to the fracture load, in the static loading MI and PI showed a higher fracture load and in dynamic fatigue protocol 2 PI showed a lower fracture load. The number of cycles until fracture only differed within three groups: MM and MI survived a higher number of cycles in dynamic fatigue protocol 2; PI survived a higher number of cycles in dynamic fatigue protocol 2 than in protocol 1. Within dynamic fatigue protocols, PM resisted the highest number of cycles in protocol 1 and 3 and MI in protocol 2. Comparing groups, Weibull modulus differed only within the static loading, with PI showing lower values than MM and MI. Within the material groups, MI showed higher values in static loading than in dynamic fatigue protocol 1 and 2, and PI showed higher values in the dynamic fatigue protocol 3 than in static loading. With regard to fracture patterns, no differences were found between the groups.

CONCLUSIONS

Dynamic fatigue protocols provide clinically relevant information on the long-term stability and reliability of monolithic strength-gradient zirconia materials. However, no definitive instructions for dynamic testing can be provided from this investigation.

Item Type:

Journal Article (Original Article)

Division/Institute:

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

UniBE Contributor:

Buser, Ramona

Subjects:

600 Technology > 610 Medicine & health

ISSN:

1751-6161

Publisher:

Elsevier

Language:

English

Submitter:

Tina Lauper

Date Deposited:

30 Jun 2021 14:49

Last Modified:

04 Jul 2021 03:08

Publisher DOI:

10.1016/j.jmbbm.2021.104504

PubMed ID:

33845296

Uncontrolled Keywords:

CAD/CAM materials Dynamic testing Fatigue Multi-generation zirconia Strength-gradient zirconia Zirconia

BORIS DOI:

10.48350/157027

URI:

https://boris.unibe.ch/id/eprint/157027

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