| Impact of Experimental Protocols on the Flexural Strength
Testing of Lithium Disilicate-Based Dental Glass-Ceramics |
Xinyi Xu,a Joseph Youngb and Ashutosh Goela, *
Pages : 258-264
DOI : 10.1080/0371750X.2021.2004443 |
| Abstract |
| The transition of dental ceramics and glass-ceramics (for fixed all-ceramics and
metal-ceramics restorations and prostheses) from laboratory to clinic requires the
materials to pass through a series of tests following the protocols and requirements
discussed in the standard ISO 6872:2015. However, the literature reveals that the
researchers in the dental ceramics community usually do not adhere to the ISO
standard’s specifications when measuring their materials’ flexural strength, assuming
that these deviations from the protocols exhibit minimal or no impact on the materials’
strength. Therefore, the present study aims to fill that gap by elucidating the impact
of the following experimental protocols – (i) polishing, (ii) edge chamfering and
(iii) adhesive tape on the non-tensile side – on three-point flexural strength of lithium
disilicate based glass-ceramics. The result reveals that polishing increases flexural
strength and tends to introduce edge or corner flaws in the specimen. Though edge
chamfering of specimens did not help remove the edge defects in our study, it leads
to a tighter flaw distribution, increasing the reliability of the flexural strength results.
The application of adhesive tape (on the compressive side) exhibits an insignificant
impact on the glass-ceramic specimens’ flexural strength. Accordingly, revisions have
been suggested in the ISO 6872 standard.
[Keywords: Oxide materials, Amorphous materials, Mechanical properties, Scanning
electron microscopy, X-ray diffraction] |
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