Despite the strength of e.max lithium disilicate ceramic from Ivoclar and the fact that they do not fracture, they can still get recurrent caries, suffer from open margins or need to be replaced for other reasons. The exact thing that we love about e.max, its strength, is a challenge when one has to be removed. I have learned several great tips for when I do find myself in the position of having to remove something made of e.max.
First, although it sounds counter intuitive, use fine diamonds instead of coarse. When you try to cut e.max with a coarse diamond, the diamonds get stripped off of the shank of the bur and you find yourself very quickly cutting with a shiny stainless steel shank, making no progress at all. Fine diamonds will last through the process and cut more efficiently. With the fine diamond make a slit up the crown from buccal to lingual all the way through to the cement layer. Next place a slit from mesial to distal to the cement layer as well. If you placed the original crown and know what it is cemented with the next step will be easier.
If the restoration was cemented with traditional cement, place a crown remover or plastic instrument in the slits and twist gently. The pieces should begin to come off under gentle pressure, do not force. If they do not separate at the cement layer, begin to make more slices and smaller pieces. If the crown was placed with an adhesive process and truly bonded in place you can try to make multiple small pieces and twist, but this doesn’t work that often. When I have to remove a bonded restoration I use multiple fine diamonds and prep away the e.max and the cement until I am back to a fresh prep. This removal process is one reason to consider traditional cementation when using e.max on a prep that has retention and resistance form and does not require bonding.
I think we all have had a severe disdain for the removal of E-Max. The fine diamonds work but it can be a very arduous process. About two years ago I set out to find a better way, which Dr. Brady has now inspired me to share.
1 Diamond wheel. I use a Shofu Robot PN895C-1.
Copious water.
Go into the E-Max hard and aggressive. Bonded or cemented it will splinter off. I am a total etch guy, and it still works. Sometimes you have to go at a little funky angle to move towards the interproximal but the removal is fast and easy. You can go up the Buccal and Lingual walls if you need to with the edge of the wheel, copious water; this definitely is not a heat free process. I have not had one tooth turn on me from removal this way. If I need to do any additional removal interproximal, very rare, I use an Axis Zirconia bur. All burs are garbage after this. BTW – This is more for large coverage onlays and crowns. Pull out the fine diamonds for smaller onlays, but I usually use empress for those. Hope this helps.
Thanks Greg, I’ll give it a try the next time I need to get an e.max off.
Lee
what if I wanted to remove it one piece to re-cement it?!
Removing in one piece is much more complicated. If it has been cemented with glass ionomer or something similar and not bonded you can try tapping it off, using a crown remover, or even the Almore crown remover gummies. If it is bonded getting it off in one piece is not an option based on my understanding.
Lee
If you want it off in one piece, look into hard tissue laser. marj – thanks for the great post Lee Ann