Why A Precision-Fit Implant-Abutment Interface Matters


What factors should you consider when choosing components for your restoration? One important aspect is whether the components have been designed and manufactured to work together as a precise system. We discussed this topic with Prof. Dr. Matthias Karl of Saarland University in Germany, to learn more about why precision matters and the risks of overlooking it.


Perfect fit between abutment and implant collar. Forces are evenly distributed and uncontrolled peak stresses avoided. 
Image © Schüpbach Ltd

What are the consequences of using components that do not fit precisely?

Prof. Matthias Karl (pictured left): “You run the risk of damaging the interface of the implant and the abutment. I consider this as the most critical factor and we see many of these cases coming into our clinic. In many cases the implant has been in place for a very long time but the restoration has since been replaced.

For example, perhaps a patient needed a single implant when they were 30 years old, but now they’re over 55 years old and need a removable restoration. You have to exchange the abutment and as the treating clinician you want to be sure that the implant itself is still OK and that there are no micro fractures or other wear phenomena.”

Can clinicians check precision of fit for themselves?

Prof. Karl: “When we look at precision from a clinical perspective then we have two choices intraorally to check for precision of a crown or of a restoration. We either take a probe –which shows a thickness of a couple of microns– and we try to find a gap somewhere. The second option is to use silicone as a medium to measure gaps, or to get an impression of a gap. To assess for gaps between the implant and the abutment, the explorer is basically useless, and you would not really insert silicone into the body of an implant. So you really have to rely on the manufacturer of your components.”

“The manufacturer is able to determine what might be the gap and what might be the tolerance, and what is the tolerance in the worst-case scenario. As a clinician you have to rely on the manufacturer of your implant components.”

Mismatching components can lead to uncontrolled peak forces, which can cause implants to fracture. Image © Schüpbach Ltd

How can a clinician be confident that an abutment is going to fit precisely on an implant?

Prof. Karl: “Go for properly documented abutments. I haven't had a single patient for whom the cost of the abutment or the prosthetic components would have led to the rejection of a treatment plan. This has never been the case throughout my career.”

What would you tell clinicians who are unsure about the best choice of a restorative component?

Prof. Karl: “Don't play with the oral wellbeing of your patients. It's not worth it. It's not worth the pain. The patient will come back to your office and you’ll have to fix it.”

“In my opinion, it's very important that clinicians understand that an implant is not just a screw that goes into bone. It's the whole system. It's the whole approach. You have to consider the quality of the implant, abutment, impression compound, lab components and restoration. You have to understand the whole workflow. It has to be perfect in order to have the best chance of a long-lasting restoration.”