IPS e.max® has been one of my favorite materials for restoring posterior teeth. IPS e.max is a lithium disilicate material that is available in a block form to use chairside with CAD/CAM systems as well as in an ingot form to be pressed in the laboratory. As per Ivoclar Vivadent, Inc. the biaxial strength of IPS e.max is 500 MPa and is categorized under high strength ceramic restorative materials. IPS e.max is available in different translucencies HT (high translucency), LT (low translucency) and the newly available MT (medium translucency).
In this video, I will discuss how and when I will use HT and LT IPS e.max blocks for restoring posterior teeth in my clinical practice.
HT does a great job of blending in with the coronal tooth structure because of its high translucency that is similar to enamel. So, I use HT on partial coverage clinical situations like inlays, onlays and crownlays - where I am primarily replacing the enamel. It works great as most of my tooth reduction is within the enamel and my margins are supra-gingival. Most situations even above the height of contour and isolated.
LT has this unique ability to mask dark stumps because of its comparatively low translucency so I tend to use it for complete coverage crowns, teeth where I need to block a dark stump or when I am using it next to a PFM or a zirconia crown. When doing full coverage crowns my preparation is within the dentin. Using LT allows me to block the tooth structure appropriately without the final results ending up looking grey if HT is used.
I would like to disclose that these are just recommendations based on my experience and one should always use their best clinical judgement when choosing the correct restorative material. There are always exceptions to the rule. I would like to share this video with all my dentist friends and I hope that it will help you understand my usage of IPS e.max HT and LT blocks for restoring posterior teeth.