e.Max Preparation Guide - Posterior Single Unit Crowns
Posted on 09/12/2011
Probably the two most common reasons for a doctor to avoid all ceramic
restorations - especially e.Max - is due to (1) the preparation technique
and (2) cementation guidelines. Many doctors are comfortable with
preparation styles for PFM - especially the chamfer, chamfer bevel or knife
edge - and would rather not try to create the shoulder necessary for an
e.Max. Additionally, many doctors are experts at cementing the PFM, but are frustrated with the techniques and materials required to cement the all
ceramic restoration.
Over the next several blog posts, we will discuss both of these issues.
Indeed, it is true that the E.max requires a shoulder prep for a crown. But
the truth is that the same shoulder is required for a porcelain butt joint
margin on a PFM. So for doctors who dislike the graying margin that shows
up over time on the PFM and always request a Butt Joint for anterior cases,
it is a good idea to consider e.Max since you avoid the graying margin and
may save some money- since there is no additional butt margin fee on an all
ceramic.
As far as the technical specification for preparation of the e.Max crown, we
will highlight the guidelines issued by Ivoclar in this blog and the next
few blogs:
POSTERIOR - Single Unit Crown
- 1.5mm occlusal reduction
- 1.5mm axial reduction
- 1.0mm reduction at gingival margin
- Use a flat ended, tapered diamond to create a shoulder margin
For conventional cementation please be aware of the following
- Coronal length (i.e. abutment height) of at least 4.0mm
- Shoulder prep must have at least 1.0mm of proximal reduction
- Occlusal reduction of at least 1.5mm in contact area
- Taper between 4 and 8 degrees
Here is a picture guide. Source: Ivoclar Chairside Preparation Guide for
IPS E.Max available here: http://www.ivoclarvivadent.us/empress/documents/all_ceramic_prep_guide.pdf
restorations - especially e.Max - is due to (1) the preparation technique
and (2) cementation guidelines. Many doctors are comfortable with
preparation styles for PFM - especially the chamfer, chamfer bevel or knife
edge - and would rather not try to create the shoulder necessary for an
e.Max. Additionally, many doctors are experts at cementing the PFM, but are frustrated with the techniques and materials required to cement the all
ceramic restoration.
Over the next several blog posts, we will discuss both of these issues.
Indeed, it is true that the E.max requires a shoulder prep for a crown. But
the truth is that the same shoulder is required for a porcelain butt joint
margin on a PFM. So for doctors who dislike the graying margin that shows
up over time on the PFM and always request a Butt Joint for anterior cases,
it is a good idea to consider e.Max since you avoid the graying margin and
may save some money- since there is no additional butt margin fee on an all
ceramic.
As far as the technical specification for preparation of the e.Max crown, we
will highlight the guidelines issued by Ivoclar in this blog and the next
few blogs:
POSTERIOR - Single Unit Crown
- 1.5mm occlusal reduction
- 1.5mm axial reduction
- 1.0mm reduction at gingival margin
- Use a flat ended, tapered diamond to create a shoulder margin
For conventional cementation please be aware of the following
- Coronal length (i.e. abutment height) of at least 4.0mm
- Shoulder prep must have at least 1.0mm of proximal reduction
- Occlusal reduction of at least 1.5mm in contact area
- Taper between 4 and 8 degrees
Here is a picture guide. Source: Ivoclar Chairside Preparation Guide for
IPS E.Max available here: http://www.ivoclarvivadent.us/empress/documents/all_ceramic_prep_guide.pdf
