Abstract
Statement of problem
Whether procedures performed before the cementation of computer-aided design and computer-aided
manufacturing (CAD-CAM) glass-ceramic restorations, including milling, fitting adjustment,
and hydrofluoric acid etching introduce defects on the ceramic surface that affect
the mechanical and surface properties is unclear.
Purpose
A systematic review and meta-analysis were conducted to assess the effect of milling,
fitting adjustments, and hydrofluoric acid etching (HF) on the flexural strength and
roughness (Ra) of CAD-CAM glass-ceramics.
Material and methods
Literature searches were performed up to June 2020 in the PubMed/MEDLINE, Web of Science,
and Scopus databases, with no publication year or language limits. The focused question
was “Do milling, fitting adjustments, and hydrofluoric acid etching affect the flexural
strength and roughness of CAD-CAM glass-ceramics?” For the meta-analysis, flexural
strength and Ra data on milling, fitting adjustment, and HF etching versus control
(polishing) were analyzed globally. A subgroup analysis assessed the effect of etching
parameters (HF concentration and time) on the flexural strength and roughness of CAD-CAM
glass-ceramics with different microstructures. Comparisons were performed with random-effect
models at 5% significance.
Results
Fourteen studies from 2764 potentially relevant records were included in the qualitative
syntheses, and 12 in the meta-analysis. Milling and fitting adjustments increased
roughness and reduced the flexural strength of CAD-CAM glass-ceramics. The effect
of HF etching was dependent on the glass-ceramic microstructure, HF concentration,
and etching time. For feldspathic- and leucite-reinforced ceramics, HF 5% applied
for between 30 and 120 seconds increased roughness without affecting flexural strength.
For lithium disilicate glass-ceramics, HF concentrations greater than 4.9% used for
20 seconds or more reduced the strength without affecting the surface roughness.
Conclusions
The flexural strength of CAD-CAM glass-ceramic is reduced by grinding procedures such
as milling and fitting adjustment. Ceramic microstructure, HF concentration, and etching
time determined the effect of hydrofluoric acid etching on the flexural strength and
surface roughness of glass-ceramic materials.
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Article info
Publication history
Published online: April 14, 2021
Footnotes
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Identification
Copyright
© 2021 by the Editorial Council for the Journal of Prosthetic Dentistry.
