Sameer Puri D.D.S. As you may know, we have two different types of e.max blocks. We have a high translucency version and a low translucency version - essentially this is where the moniker HT and LT comes from. Different clinicians have different preferences on which block is their favorite.
Rather than go into the reasons and argue why I like to use the blocks I like to use, I would rather take this space and discuss why I use the blocks that I do and in which situations.
When it comes to esthetics, the more translucent the material, the better the esthetics. We know this because lab techs spend countless hours cutting back the porcelain to try to get more incisal translucency, aka better esthetics. The only downside to this is when our substructure is discolored. We wouldn’t want to use a translucent material with a dark substructure - all that will do is make the end result a darker than desired final restoration. This is where we want to use a more opaque material.
Zirconia, for example, has been known in the past to be opaque - yes they are coming out with more translucent zirconia now but essentially zirconia blocks have been traditionally opaque. Opaque usually equals ugly. The more opaque materials tend to not allow any transmission of the underlying tooth structure - which is great when you want to block out a dark stump, not so great when you want to maximize esthetics.
This leads us back to the original question - should we use e.max LT or emax HT? The more translucent version of the material or the more opaque? My rule of thumb is this - I usually prefer the more translucent version, the HT block. The HT block gives me better esthetics as it tends to blend in with the surrounding tooth structure.
Usually I will recommend the HT block when the surrounding tooth structure is all natural, aka virgin teeth. The HT melts into the adjacent teeth and in my opinion gives great esthetics.
When do I recommend the LT block? When the surrounding teeth are not natural teeth but are instead restored with PFM restorations. I then recommend that LT blocks be used. The increased opacity of the LT blocks works better to blend into the adjacent tooth structures and look more like a PFM. See the case below - One of the restorations is an e.max LT block on an implant and custom abutment. All the rest are natural teeth restored with PFM restorations fabricated by a lab. Which is which?
So when it comes to HT vs LT- my choice is usually HT. Especially when the restored tooth is surrounded by adjacent virgin teeth. But if you have a bunch of PFM restorations- that is the time to use the LT block.
