Acoustic emission and finite element study on the influence of cusp angles on zirconia dental crowns

Ayman Ellakwa; Raju Raju; Cai Sheng; Ginu Rajan; B Gangadhara Prusty

doi:10.1016/j.dental.2020.09.007

Acoustic emission and finite element study on the influence of cusp angles on zirconia dental crowns

Dent Mater. 2020 Dec;36(12):1524-1535. doi: 10.1016/j.dental.2020.09.007. Epub 2020 Sep 25.

Authors

Ayman Ellakwa¹, Raju Raju², Cai Sheng³, Ginu Rajan⁴, B Gangadhara Prusty⁵

Affiliations

¹ Biomaterials Unit & Department of Prosthodontics and Oral Rehabilitation, Sydney Dental School, University of Sydney, Sydney, NSW 2010, Australia. Electronic address: ayman.ellakwa@sydney.edu.au.
² School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: raju@unsw.edu.au.
³ School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
⁴ School of Electrical, Computer & Telecommunications Engineering, University of Wollongong, Wollongong, NSW 2522, Australia.
⁵ ARC Centre for Automated Manufacture of Advanced Composites, School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia.

PMID: 32981750
DOI: 10.1016/j.dental.2020.09.007

Abstract

Objective: The effect of cusp angle on the load-carrying capacity and failure behaviour of BionZ Diamond zirconia crowns is carried out using experimental and numerical investigations.

Methods: The experimental program using monolithic crowns were divided into three groups (n = 14) for three cusp angles, 60, 80 and 120 degrees and were tested to failure under the static load. A 2-channel acoustic emission (AE) system was used to monitor the failure process while the piezo sensors were attached to the rigid stainless-steel jig for recoding the AE events. Load-displacement and AE response were simultaneously monitored until failure of specimens. Parametric AE analysis was conducted for the factors such as amplitude, energy released, signal duration and cumulative counts, for each AE signal. Fast Fourier transform (FFT) was conducted to assess the frequency at failure. Linear finite element analysis (FEA) was carried out using commercial software Ansys Workbench 19.1 to present the stress distribution and failure modes. Post-failure surface morphology study was carried out using scanning electron microscopy (SEM) and statistical analysis was performed using Weibull analysis.

Results: All the samples in three different groups have failed at the mid-line, splitting the zirconia crowns into two equal pieces. The load to failure was directly proportional to the cusp angle in crowns; 120° group had the highest load-carrying capacity of 2.93 ± 0.26 kN while 60 and 80° groups had a failure load of 2.46 ± 0.53 and 2.52 ± 0.16 kN, respectively. Parametric AE analysis revealed that the failure was instantaneous and 60-degree samples had higher AE signature. FE analysis showed the crack initiation at the occlusal surface of the crown which is in agreement with the SEM images. A close agreement of results for the load and stress distribution from FEA complemented with the experimental study.

Significance: Optimisation of cusp-angle could help clinicians to accurately design the monolithic zirconia crown focussing on maximum load-carrying capacity, increasing the restoration life.

Keywords: Acoustic emission; Crown failure; Cusp angle; Dental crown; Stress concentration; Zirconia.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Acoustics
Ceramics
Crowns*
Dental Porcelain
Dental Prosthesis Design*
Dental Restoration Failure
Dental Stress Analysis
Finite Element Analysis
Materials Testing
Zirconium

Substances

Dental Porcelain
Zirconium
zirconium oxide