The past few years have seen an increase of options for implant restorations. Not so much in the materials, but in the way we fabricate them. Years ago, almost everything was screw retained for many reasons:
However, there were some issues with doing every case screw retained:
In the late 90’s, I saw a movement of the implant becoming cement retained. Implant placement improved to a more centralized position in a ridge. Better and more appropriate healing abutments were selected which greatly improved the emergence profile of the restoration. Implant restorations that were cement retained had a better aesthetics.
As far as implant abutment selection, our choices were limited: Stock, Custom Stock or UCLA. Using these abutments may not have been the best for every situation, but they worked well.
In the past 10 years, Computer Aided Design (CAD) changed almost everything. Now, abutments could be designed to fit the needs of the patient, clinician and the technician. This technology has greatly improved the form and function of both the implant system and the restoration, but there was a learning curve.
In the past 5 years, there has been a move away from cement retained restorations, due to concern of not being able to properly clean cement that is below the gumline with a possibility of failure over time. Because of this there has been a move back to screw retained, meaning we would have to go back to Custom Cast UCLA abutments using Porcelain fused to Alloy. Considered a step backwards for many, this technique is prone to micro-movement causing failure of the implant.
The term “Screw-mentable” has been coined over the past few years. You can have a screw retained restoration that has been cemented to a Custom CAD (usually Gold Hue Titanium abutment.) The restoration could be Emax Epress, Porcelain fused to Zirconia, Brilliance Z (Full Contour Zirconia) and even PFM.
Here is how it works:
A Custom CAD abutment is designed and milled. We create a restoration with an access hole in the occlusal. (The access hole cannot emerge from the incisal edge or the facial.) Once completed either the technician or the clinician will cement the crown to the abutment. Since we are cementing outside of the mouth, we can clean the cement quite easily. The crown is then screwed into the implant intraorally. A majority of the restorations are Emax Epress so it is quite easy to bond composite to the access hole. The aesthetics are outstanding. Furthermore, the crown is easily retrievable.
Since an all ceramic is used with a Gold Hue Titanium abutment, there is no alloy cost. Some of my clinicians like the crown cemented at the lab, some like to try everything first, remove and cement outside the mouth chairside.
I am sure many of you are using this excellent technique. We have fabricated thousands of them. As I mentioned earlier, when you solve one problem, other problems may arise. There has been some challenges along the way. I will discuss these challenges and newer restorative options next time.