We all use ceramic restorations in our practices and will always complete a try-in step before bonding the restoration to the tooth. Some dentists mill these restorations in house and then acid etch and apply silane, and some restorations come from the lab pre-etched.

Etch vs Ivoclean

We know that if the bonding surface is contaminated with blood or saliva or try-in paste, then the bonding strength will be affected. I always paid attention to the fact that if there was blood on the intaglio surface I would have to re-etch it, but if it didn’t have copious amounts of saliva on it, I would probably have just washed and dried it and applied my silane. In a material confused state, I was doing the wrong thing.

I have asked many dentists what their protocol is and many have responded that they don’t necessarily clean the crown after trying. They didn’t have a clear understanding of the advantage of cleaning and silanating the restoration. A recent inquiry on SpearTALK addressed the efficacy of etching/silane vs Ivoclean/silane.

A scientific study back in 2009 looked at this and concluded that these restorations are best cleaned with either 37 percent phosphoric acid (e.g. Total Etch gel) or a 5 percent hydrofluoric acid.1 Additionally, if you use any fit-checker, silicone-type material, you have to use hydrofluoric acid. The study examined other techniques like using isopropanol and just water air spray, which did nothing to improve bond strength.

The part of this that I and many of my colleagues were missing was that in getting any saliva contamination was harmful, and here’s why. Saliva contains alkaline phosphatase and other phosolipids that more or less react with the surfaces of the crown rendering it inert to your primer silane. Therefore, you have to clean it. Using acid etch will render it clean and increase the bonding strength, as long as it wasn’t pre-etched.

If your restoration was pre-etched from the lab, it still requires cleaning, but you don’t want to re-etch it. Doing so removes more filler particles and renders the restoration less strong. In this case, you will want to use Ivoclean. Ivoclean consists of an alkaline suspension of zirconium oxide particles in water (which is why you have to shake the bottle well). It is strongly alkaline and thus corrosive, so you have to be really careful to wear gloves and eye protection.

The concentration and size of the particles render them more attractive to the phosphate contaminants. They absorb them like a sponge and leave behind a clean oxide surface. It in essence becomes an acid-base reaction.

Here’s the take home lesson. You can have your lab etch your restorations, but if you are trying it in first, which you undoubtedly will, you have to re-clean it. Since you don’t want to re-etch it, which will remove too many of the filler particles, you need to use Ivoclean. If you have chosen not to have your lab etch the restoration, you can etch it yourself but will need to know your ceramic as well as the concentration and time of the acid that the manufacturer recommends.

If you follow these recommendations, your incidence for crowns coming off will be greatly reduced and your satisfaction for doing all ceramic restorations will escalate.

(Click this link for an article on adjusting and polishing ceramic restorations. For more articles by Dr. Mary Anne Salcetti, click here.)

Mary Anne Salcetti, DDS, PC, Spear Visiting Faculty www.maryannesalcettidds.com

References

1. K.Klosa, S.Wolfart, F. Lehmann, H.-J. Wenz, M. Kern. The effect of storage conditions, contamination modes and cleaning procedures on the resin bond strength to lithium dislocate ceramic: J.Adhes. Dent. 11,127 (2009)


Comments

Commenter's Profile Image Muna S.
October 2nd, 2015
Great guidelines, Dr. Salcetti! Thanks for being clear on this subject!
Commenter's Profile Image Pamela M.
October 6th, 2015
Excellent article! This information is so practical and so important! Thank you!!!
Commenter's Profile Image Briana C.
October 6th, 2015
Thank you for the great info. So, if your lab etches it do you silane, try/in, then clean with the cleanser before cementing? Or, try/in, clean, then silane? And please remind me the point of silaning? It's something I've never quite grasped. Thank you so much!
Commenter's Profile Image Bridget M.
October 6th, 2015
Thanks for the thorough and scientific answer to my query, Mary Anne! :)
Commenter's Profile Image Waseema A.
November 3rd, 2015
Thanks for the thorough discussion. I spoke to my 3M rep a couple of weeks ago who said that if you are using Rely X Ultimate cement, you shouldn't use the Ivoclean. Instead, you should use use the Scotchbond since it silanates it. Your thoughts?
Commenter's Profile Image Murtuza S.
October 2nd, 2018
Great article Mary Anne, and thanks for the reminder about shaking the bottle of Ivoclean