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J Mech Behav Biomed Mater. 2016 Aug;61:328-333. doi: 10.1016/j.jmbbm.2016.04.014. Epub 2016 Apr 14.

In vitro analysis of the fracture resistance of CAD-CAM monolithic zirconia molar crowns with different occlusal thickness.

Author information

1
Department of Medical Biotechnologies, School of Dental Medicine, University of Siena, Viale Bracci, 53100 Siena, Italy. Electronic address: errestino@libero.it.
2
Department of Medical Biotechnologies, School of Dental Medicine, University of Siena, Viale Bracci, 53100 Siena, Italy. Electronic address: triulzio.clementina@gmail.com.
3
Department of Medical Biotechnologies, School of Dental Medicine, University of Siena, Viale Bracci, 53100 Siena, Italy. Electronic address: marella86@hotmail.it.
4
Department of Medical Biotechnologies, School of Dental Medicine, University of Siena, Viale Bracci, 53100 Siena, Italy. Electronic address: bonadeogianni@gmail.com.
5
Department of Dentistry, University "Vita Salute San Raffaele" of Milan, Via Olgettina 60, 20132 Milan, Italy. Electronic address: gherlone.enrico@hsr.it.
6
Department of Medical Biotechnologies, School of Dental Medicine, University of Siena, Viale Bracci, 53100 Siena, Italy. Electronic address: ferrarm@gmail.com.

Abstract

OBJECTIVES:

To compare the fracture resistance and mode of failure of CAD-CAM monolithic zirconia crowns with different occlusal thickness.

MATERIAL AND METHODS:

Forty CAD-CAM monolithic zirconia crowns with different occlusal thickness were randomly distributed into 4 experimental groups: 2.0mm (group 1), 1.5mm (group 2), 1.0mm (group 3) and 0.5mm (group 4). The restorations were cemented onto human molars with a self-adhesive resin cement. The specimens were loaded until fracture; the fracture resistance and mode of failure were recorded. The data were statistically analyzed with the one-way ANOVA followed by the Fisher׳s Exact test with Bonferroni׳s correction (p=0.05).

RESULTS:

The fracture resistance values of all the specimens exceeded the maximum physiological occlusal loads in molar regions. All the crowns showed cohesive microcracks of the zirconia core; only 1 crown with a thickness of 0.5mm was interested by a complete fracture.

CONCLUSIONS:

The occlusal thickness of CAD-CAM monolithic zirconia crowns did not influence either the fracture resistance and the mode of failure of the restorations; the occlusal thickness of CAD-CAM monolithic zirconia crowns can be reduced up to a lower bound of 0.5mm keeping a sufficient strength to withstand occlusal loads; CAD-CAM monolithic zirconia crowns showed sufficient fracture resistance to be used in molar regions, even in a thin configuration (0.5mm).

KEYWORDS:

CAD–CAM; Crown; Fracture resistance; Monolithic; Occlusal thickness; Zirconia

PMID:
27104931
DOI:
10.1016/j.jmbbm.2016.04.014
[Indexed for MEDLINE]
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