IADR Abstract Archives

Abrasion and Etching Effects on Lithium Disilicate Flexural Strength

Objectives: Lithium disilicate is a glass-containing ceramic for all-ceramic restorations. During fabrication or before bonding to the preparation, alumina oxide abrasion or HF acid-etching may be used to create micromechanical retention. Few studies have investigated how HF etching or abrasion affects the flexural strength of lithium disilicate ceramics. This study measured and compared the flexural strength of e.max CAD following alumina abrasion at differing pressures and acid-etching at differing concentrations and times.

Methods: Bars of e.max CAD (9 groups of 10 - 22mm x 2.5mm x 2.5mm) were prepared; polished sequentially (180, 320, and 600 paper); and fired following manufacturer’s instructions.  4 groups were particle abraded (30µm alumina from 10mm at 8psi, 15psi, 30psi, or 45psi for 10s). 2 groups were etched with 5% HF (20s or 2 minutes).  Two groups were etched with 9.5% HF (20s or 2 minutes). The control was polished and fired only (no treatment).  Specimens were loaded using a three point flexural test to failure in an Instron (1mm/min crosshead speed). ANOVA and Dunnett’s t-test determined intergroup differences (p= 0.05).

Results: Compared to the control, the 15psi, 30psi, and 45psi abraded groups produced significantly lower flexural strengths (p<0.05).  The 8psi treated group was not statistically different from the control (p>0.08).  The 5% and 9.5% HF etched groups were not significantly different from the control (p>0.05).

Group Mean Flexural Strength (MPa) Deviation (MPa)
Control 376.8 80
8 psi 305.3 29
15 psi 278.9 39
30 psi 240.6 31
45 psi 241.9 14
5% HF (20s) 313.7 62
5% HF (2min) 333.8 46
9.5% HF (20s) 303.5 39
9.5% HF (2min) 353.5 67

Conclusions: Alumina particle abrasion higher than 15psi significantly reduced e.max CAD flexural strength.  HF etching is recommended to increase micromechanical retention and clean the intaglio surface of the restoration prior to bonding.

AADR/CADR Annual Meeting
2014 AADR/CADR Annual Meeting (Charlotte, North Carolina)
Charlotte, North Carolina
2014
1441
Dental Materials 3: Ceramic-based Materials and Cements
  • Menees, Timothy  ( Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, USA )
  • Kalavacharla, Vamsi K.  ( School of Dentistry, University of Alabama at Birmingham, Birmingham, AL, USA )
  • Beck, Preston  ( School of Dentistry, University of Alabama at Birmingham, Birmingham, AL, USA )
  • Cakir, Deniz  ( School of Dentistry, University of Alabama at Birmingham, Birmingham, AL, USA )
  • Ramp, Lance C.  ( School of Dentistry, University of Alabama at Birmingham, Birmingham, AL, USA )
  • Burgess, John  ( School of Dentistry, University of Alabama at Birmingham, Birmingham, AL, USA )
    • Poster Session
    Dental Material Properties
    03/22/2014