4 Reasons Why e.max is Hot Right Now

You’ve probably heard of e.max crowns.  In a prior post, I discussed the latest ceramic technology and how confusing it can be.  There are a lot of products being pushed on the market by different companies and every sales representative will show you a “study” that proves their product is the greatest invention since sliced bread.

 

"And in this study here you can see our bonding agent will also cure the common cold."

 

But the hype behind e.max (Ivoclar Vivadent) is very real and worth our attention.  Let’s take a look again at the three porcelain categories, based on material:


Now let’s look at a chart of porcelain that takes brands into consideration:

There are more brands out there, but these are the ones that I’m using in my practice right now.  A longer list of brands can be found in my dental ceramic post.

So you can see that “e.max” can mean a restoration made of lithium disilicate or zirconia.  “e.max” is a brand, not a specific restoration.

I haven’t used e.max ZirCAD yet, but I’m sure it’s just fine.  Personally, when I’m using zirconia, I use NobelProcera Zirconia (Nobel Biocare).  Why?  It’s been around for a while and I’ve had great success with it.  As an aside, you can actually use Procera scanning technology for the CAD part of e.max ZirCAD.  Totally compatible.

Anyway, the real excitement over e.max restorations has been due to their lithium disilicate product line.  Here’s why:

(1) It can be pressed or made with CAD/CAM

There are now two ways to fabricate your lithium disilicate restorations: pressed to the model or CAD/CAM.  Pressing the material is done in a similar way that metal frameworks are cast to a model.  A wax-up of the planned contours is created on the model, sprued, invested, and heated material is spun into the void in the stone.  The average compressive strength of e.max Press is 400 MPa.

Alternatively, a scan of the model allows the technician to design a digital wax pattern and mill it from a solid block of lithium disilicate.  This is faster and less expensive than the press technique.  The compromise is that the compressive strength of e.max CAD drops to 360 Mpa.


It is important to note that 360-400 MPa are in the middle range of compressive strengths for the new porcelains and that frequent fractures of lithium disilicate have not been reported.   That being said, e.max CAD is not recommended for posterior full coverage crowns by the manufacturer.

(2) It can be monolithic or veneered

One of the major complaints about  all-ceramic crowns is that the veneering ceramic chips or fractures from the underlying ceramic coping.  If you’re using zirconia as your coping, you’ll definitely need a veneering ceramic to mask the bright white color of zirconia.

 

Zirconia crown with veneering ceramic. Note the bright white appearance of zirconia internally.

 

But lithium disilicate is actually quite esthetic.  Thus it can be made monolithic, or full contour, in areas that are not esthetically demanding without a problem.  If your restoration is in an area that requires maximum esthetics, you may want to have the lab leave room in the lithium disilicate coping for some cosmetic veneering porcelain.  It’s nice that you have both options with the same material.

Monolithic lithium disilicate. The intaglio surface appears frosty because it has been treated with hydrsulfuric acid for bonding.

(3) It can be used for inlays, onlays, or crowns

Ever hear of a zirconia inlay?  Me neither.  Bonding concerns and an unesthetic, bright white appearance prevent zirconia from routinely being used as an inlay/onlay material.

The ideal inlay/onlay material is monolithic (doesn’t require veneering porcelain) and is able to be bonded to the tooth, rather than cemented.  Which leads me too…

(4) It can be predictably bonded to the tooth

As I discussed in my last post, not all porcelains can be predictably bonded.  Let’s look at the current cements on the market that permit bonding to porcelain:


Only total-etch and self-etch resin cements can truly, predictably, and esthetically bond to a porcelain with a glassy matrix, e.g. glass ceramics and glass ceramics with fillers.  Glass-free ceramics, like zirconia, are better suited to cementation with a self-adhesive or resin-modified glass ionomer cement.  There won’t really be much adhesion, so you will have to rely on traditional porcelain-fused-to-metal crown preparation techniques for mechanical retention.

Since lithium disilicate can be bonded to the tooth, we are allowed to use more conservative preparation techniques that don’t remove unnecessary tooth structure.  More on that coming soon!

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22 Comments

  1. Bill Johnson says:

    Please review the IPS e.max CAD instructions for use. Your comment about not being recommeneded by the manufacturer for posterior use is completely contrary to what the instructions say.

    • Chris says:

      The latest brochure from the company can be downloaded at this link here. According to their data, the HT (high transparency) and LT (low transparency) blocks can be used for single posterior crowns. However the MO (medium opacity) blocks are still only indicated up to the second premolar.

      • Sehnaz Kazokoglu says:

        The strength of IPS e.max CAD is enough for a posterior single tooth and IPS e. max CAD is routinely used. HT, LT, MO blocks are chosen regarding to esthetic requirements. Successful outcomes are evident by both investigators and CAD-CAM users.
        For example:http://www.ncbi.nlm.nih.gov/pubmed/23135425

        • Chris says:

          Thanks, Sehnaz. When I originally wrote the article, Ivoclar did not advocate using e.max CAD in the posterior. Either they changed the formula or they were perhaps being too cautious when they listed the specifications. It looks like CAD can be used successfully in the posterior. Thanks!

          • Diego Prates says:

            Hi Chris, would you consider editing your post for better clarity on the manufacturer recommendation regarding IPS e.max CAD?

            As a patient I’ve been using your posts as a resource for information and this almost made me argue with my dentist on his recommendation. Of course I’ll comment it anyway. :-)

            Great material, thanks for sharing!

          • Chris says:

            I do update my posts, however what the manufacturer state and what the dentist is comfortable doing are not always the same thing. Ultimately it is the dentist’s responsibility to choose the material he/she wants to use in a given clinical situation.

  2. Pingback: “Surgical-Restorative Resource” Update #2 | The Curious Dentist

  3. Im interested how are your experiences regarding single anterior restaurations, LT or HT, cut back technicque or staining?
    Im also interested if someone made experiences with HO blocks for individual implantabutments? Does it work well?

    • Chris says:

      Great question. I consulted with Steven Pigliacelli, CDT and Vice President and Director of Education at Marotta Dental Studio, Inc. Here is what he said:
      “Definitely LT cut back technique (pressable, not milled or Cerak). We have not worked with the HO blocks yet, primarily due to the fact that I feel they will break, I don’t even like zirconia abutments for this reason.”

    • Chris says:

      I did some additional research that confirms Steven’s thoughts. LT blocks are best for the anterior region using a cut-back technique. The restoration will no longer be monolithic as you are cutting back to allow room for more esthetic feldspathic porcelain.

  4. Ashley Burnham says:

    There are specific translucent full contour zirconia materials available which are colour graduated within the material. They have very good aesthetics and are not bright like the ones made from unsuitable framework type zirconia. These restorations are very strong at around 1100 mpa but are actually a lot softer to adjust than emax. For bonding a thin layer of ceramic glaze is fired onto the fitting surface and acid etched making them suitable. Inlays and onlays look very good. For zirconia/ layered ceramics there is no need for a bright framework it depends which brand you are using. Some are available in a full colour range and different translucency options.

  5. Mary says:

    I have #12&13 zirconium implants. Can I place emax crown over? Will emax crowns provide sufficient strength for the posterior biting?

    • Chris says:

      You can have emax crowns placed over zirconia abutments. However a zirconia crown would certainly be stronger. I would recommend zirconia crowns in this case.

  6. I do a lot of emax cad/cam restorations and use multilink to bond. I have quite a bit of post-op sensitivity. I’m frustrated. I do exactly what the directions say to do. Do you have any advice?
    Thanks

    • Chris says:

      Very interesting. I haven’t had issues with post-op sensitivity with Multilink Automix. My guess is that it could be related to the depth of the preparation or the fit of the cad/cam restoration?

  7. Paulo says:

    Dr Chris,
    2013 December.
    e.max is STILL Hot Right Now?

    • Chris says:

      Oh I would definitely say so. Although I wrote this post almost three years ago, I think lithium disilicate (and e.max in particular) is still a big seller. And those numbers will continue to rise as dentists decrease their use of the old PFMs. The only other “competition” for lithium disilicate is zirconia, but they are both enjoying heavy usage.

      • Paulo says:

        Dear Dr. Chris
        Let me ask another question:

        I am not sure about the right investment (and maybe others owners of small dental lab).

        a) e-max press System.
        advantages: Fast to learn and fast to make money (and with this money buy CAD/CAM). Not too expensive.

        disvantages: CAD/CAM zirconia and lithium disilicate (e-max CAD). What impact will this have on the sales of pressable all-ceramic crowns and bridges? Even PFM market decreasing the press System will live for many years? (and considering 2 years to payback the press System)

        b) CAD/CAM
        advantages: preparing the Lab to the inevitable future. (take part or die)

        disvantages:
        Slow to learn and to make money.
        Expensive, prices still high.
        In my case would by only the CAD now ( I have no money to buy the whole system)

        I am myopic or blind to see other points?

        • Chris says:

          Ah, I think I understand your question better now. So you’re a dental lab owner. Well it’s hard for me to comment on the lab economics of buying a lab CAD/CAM machine but I can share some thoughts. I think CAD/CAM is already a large part of business for medium and large labs. They can handle more units of crown and bridge because they have one or more machines. Although the start up cost is high, the profit margins are apparently better for the lab. I think a smaller lab can still take advantage of this technology even though it may be more difficult to spend the money to set it up.
          Right now, there is still a need for e.max Press (non-CAD/CAM). E.max Press is a little stronger than e.max CAD and so some labs prefer to use Press for posterior bridges. However I think those same posterior bridges can be done in zirconia as well. E.max Press may not be the way of the future as we gain more confidence in CAD/CAM e.max and zirconia.

  8. Jodi says:

    I’m having an emax crown put on an implant soon. Had no idea there were different sorts, but I have just read that ceramic crowns contain 45% aluminium(?). I am trying hard to avoid metals apart from titanium as I have many allergies. Are we now to believe that ‘ceramic’ crowns are not actually ceramic – at least some of the time?

    • Chris says:

      Emax is made of lithium disilicate, which is clasified as a glass ceramic. I am unaware of any aluminium that is present. Do you have a source for this?

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