PAEK and zirconium oxide in everyday laboratory life and interesting aspects from materials science
by Annett Kieschnick, Jacqueline Riebschläger, Bogna Stawarczyk
Double crowns made of gold-containing or precious metal-free alloys have been tried and tested anchoring elements for decades. New material variations are increasingly becoming established, e.g. B. zirconium oxide and thermoplastic high-performance materials. What do the studies say and are there any studies on this from dental materials science? The authors address practical questions.
What significance does the material of the primary crowns have in connection with electroplated secondary parts?
In general, in-vitro studies show that electroplated abutments have no negative influence on the retention forces, regardless of the material of the primary crown. Due to the price of gold, electroplated abutments are often replaced with PAEK abutments. The experiences from everyday life are good. However, there is currently a lack of scientific evidence.
Are there significant differences between the retention power of primary crowns made of zirconia and cobalt-chrome alloys?
Both materials lead to comparably good results. However, due to biocompatibility, a large number of alloys should be avoided when treating a patient. If the patient is only treated with an alloy, e.g. B. Cobalt-chromium alloy, this restoration is certainly very good from the biological, mechanical and economic aspects.
Primary parts made of zirconium oxide – what strength or material characteristics should you pay attention to?
This question is difficult to answer. It is not just the strength values of the materials of the primary parts that are crucial for good long-term stability. The fit, edge stability and the quality of the bond between the primary crown and the tooth or implant structure also play an important role here. We currently have four different generations of zirconium oxide. From a gut feeling, one could say that all four material groups can be recommended for primary crowns if they are carefully manufactured and secured well.
What influence does the processing technology have on the retention forces for secondary crowns made of PAEK and what role does the cone angle play?
In crown and bridge technology, it was observed that CAD/CAM-manufactured PAEK restorations led to higher breaking load values than the pressed thermal loads. The processing technology plays a minor role in secondary crowns. Studies show that PAEK materials can only be used for telescopic crowns (primary parts). Conical primary parts made of PAEK are contraindicated due to the lower retention forces.
Is it possible to make primary crowns from PAEK?
Yes, primary crowns made of PAEK show good retention forces in combination with PAEK secondary crowns in in-vitro studies. It should be noted that PAEK materials require a lot of care. The materials are therefore contraindicated in patients with poor oral hygiene. More frequent tooth cleaning is also recommended with these materials. Experience has shown that no abrasive toothpastes should be used for cleaning. A tip from everyday laboratory life is washing up liquid and cotton swabs (Q-tips) or a soft brush. However, we do not yet have any clinical studies on this material combination.
How high is the risk that secondary parts made of PAEK will discolor from the inside?
Here again, PAEK materials require intensive care. In-vitro studies show that these materials e.g. B. have a strong tendency to discolor due to carrot juice and consumption with Fishermans. By detecting and eliminating discoloration early, penetration into the interior of the material can be prevented.
How can a secondary structure made of thermoplastic materials (PAEK) create a stable bond to the veneer (e.g. plastic)?
There are several points to consider here:
- The layer thickness of the abutment should not be less than 1,5 mm if the abutment is in direct contact with the antagonist. Reason: PAEK materials are plastically deformable.
- The layer thickness of the veneering plastic should not be higher than 1 mm.
- The framework pre-treatment for the composite is crucial: with Al2O3 corundum blasting (50 µm, 2 bar) and directly apply the adhesive system. Here shows e.g. B. visio.link (bredent) has very good bonding values in the in-vitro studies.
- Using opaquer increases adhesion.
First publication article: Quintessenz Zahntechnik 2018;44(4):555-557
