Hydrofluoric acid concentrations: Effect on the cyclic load-to-failure of machined lithium disilicate restorations.

Abstract

OBJECTIVES:

To evaluate the effects of the etching with different hydrofluoric acid (HF) concentrations on the cyclic load-to-failure (CLf) of machined lithium disilicate crowns cemented to dentin analogue material.

METHODS:

Pairs of dentin analogue prosthetic preparations and lithium disilicate ceramic crowns with simplified and standardized designs were machined (n=18). The preparations were etched with 10% HF (60s), followed by primer application. The intaglio surface of the ceramic crowns was treated as follows: non-etched (control, CTRL); or etched for 20s with different HF concentrations - 3% (HF3), or 5% (HF5), or 10% (HF10). A silane coating was then applied onto the treated ceramic surfaces, and they were adhesively cemented to the preparations. To perform the fatigue tests (staircase approach), a hemispheric stainless-steel piston (Ø=40mm) applied cyclic loads in the center of the crowns under water (initial load: 720N; step-size: 70N; cycles: 500,000; frequency: 20Hz). Additionally, topographic, fractographic, and fractal analyses were carried out. The fatigue data were analyzed using the Dixon and Mood method.

RESULTS:

Although the topographic and fractal analyses depicted the action of HF etching altering the superficial complexity and topography, the preponderant topography pattern was established by machining on CAD/CAM. All groups showed similar CLf (in N) (CTRL=805.00±91.23; HF3=781.25±29.87; HF5=755.00±154.49; HF10=833.75±100.74).

SIGNIFICANCE:

Etching with different HF acid concentrations did not promote a deleterious effect on the cyclic load-to-failure of machined lithium disilicate crowns.

• Authors: Catina Prochnow, Andressa Borin Venturini, Luís Felipe Guilardi, Gabriel Kalil Rocha Pereira, Thiago Augusto Lima Burgo, Marco Cícero Bottino, Cornelis Johannes Kleverlaan, Luiz Felipe Valandro
• Journal: Dental materials : official publication of the Academy of Dental Materials (Dent Mater) Vol. 34 Issue 9 Pg. e255-e263 (09 2018) ISSN: 1879-0097 [Electronic] England
• PMID: 30031547 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Chemical References

• IPS e.max CAD LT
• Silanes
• lithia disilicate
• Dental Porcelain
• Hydrofluoric Acid

Topics

• Acid Etching, Dental (methods)
• Computer-Aided Design
• Crowns
• Dental Porcelain (chemistry)
• Dental Restoration Failure
• Dental Stress Analysis
• Hydrofluoric Acid (chemistry)
• Materials Testing
• Silanes (chemistry)
• Stress, Mechanical
• Surface Properties