Apex Information Exchange Forum Index Apex Information Exchange
Hosted by Dr. John Kanca III DMD
 
 FAQFAQ   SearchSearch   UsergroupsUsergroups   REGISTER 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Visit Apex Dental Materials     Upload Photos To Your Post


HF etching weakens lithium disilicate ceramics

 
Post new topic   Reply to topic    Apex Information Exchange Forum Index -> Literature
View previous topic :: View next topic  
Author Message
john kanca



Joined: 14 May 2005
Posts: 6346

PostPosted: Thu Nov 26, 2009 8:06 am    Post subject: HF etching weakens lithium disilicate ceramics Reply with quote

J Prosthodont. 2008 Jul;17(5):415-9. Epub 2008 May 9. Links
Effect of surface acid etching on the biaxial flexural strength of two hot-pressed glass ceramics.
Hooshmand T, Parvizi S, Keshvad A.
Research Center for Science and Technology in Medicine, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran. hoshmand@sina.tums.ac.ir
PURPOSE: The purpose of this study was to assess the effect of surface acid etching on the biaxial flexural strength of two hot-pressed glass ceramics reinforced by leucite or lithium disilicate crystals. MATERIALS AND METHODS: Forty glass ceramic disks (14-mm diameter, 2-mm thick) consisting of 20 leucite-based ceramic disks (IPS Empress) and 20 lithia disilicate-based ceramic (IPS Empress 2) were produced by hot-pressing technique. All specimens were polished and then cleaned ultrasonically in distilled water. Ten specimens of each ceramic group were then etched with 9% hydrofluoric (HF) acid gel for 2 minutes and cleaned ultrasonically again. The biaxial flexural strength was measured by the piston-on-three-ball test in a universal testing machine. Data based on ten specimens in each group were analyzed by two-way ANOVA (alpha= 0.05). Microstructure of ceramic surfaces before and after acid etching was also examined by a scanning electron microscope. RESULTS: The mean biaxial flexural strength values for each group tested were (in MPa): nonetched IPS Empress = 118.6 +/- 25.5; etched IPS Empress = 102.9 +/- 15.4; nonetched IPS Empress 2 = 283.0 +/- 48.5; and etched IPS Empress 2 = 250.6 +/- 34.6. The results showed that the etching process reduced the biaxial flexural strengths significantly for both ceramic types (p= 0.025). No significant interaction between the ceramic type and etching process was found (p= 0.407). CONCLUSION: From the results, it was concluded that surface HF acid etching could have a weakening effect on hot-pressed leucite or lithia disilicate-based glass ceramic systems.
_________________
"You need me on that wall."


"You don't have a town named after you"
Back to top
View user's profile Send private message
Pav



Joined: 10 Mar 2008
Posts: 424

PostPosted: Thu Nov 26, 2009 8:43 am    Post subject: Reply with quote

Why on Earth would you ever need HF in dentistry? Cool
_________________
Don't concentrate on the finger or you'll miss all the heavenly glory
Back to top
View user's profile Send private message Visit poster's website
john kanca



Joined: 14 May 2005
Posts: 6346

PostPosted: Thu Nov 26, 2009 10:13 am    Post subject: Reply with quote

Pav wrote:
Why on Earth would you ever need HF in dentistry? Cool


Golly- good question!

Wink
_________________
"You need me on that wall."


"You don't have a town named after you"
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Apex Information Exchange Forum Index -> Literature All times are GMT - 5 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group