5 tips for your work with PEEK in the
CAD/CAM-process

We recently looked at biocompatible materials in dental technology. The high-performance plastic PEEK, which we are dealing with today, is one of our Big 3 biocompatible materials.

We have already mentioned in our wiki article PEEK plastics that processing PEEK plastics is not always easy. Now we would like to give you 5 tips to help you lose your fear of this exciting material and take advantage of the full range of benefits that PEEK brings.
 

Tip 1: Think of PEEK right from the start

Frameworks milled from PEEK - with the help of the latest CAD/CAM-technology - require more space than you might be used to from filigree frameworks made of cobalt-chrome (CoCr) or titanium . If you have reached an early agreement with the patient and dentist on dentures made of PEEK plastics, the dentist can take this decision into account during the preparation and create enough space for a PEEK restoration.

In order to give you a rough idea of how much more voluminous a framework made of PEEK has to be, we compare the clasp strengths of a partial framework (RPD) made of cobalt-chrome with those of a CAD/CAM manufactured PEEK partial framework (RPD) below.
 

 

Section area

Width

Thickness

  CoCr PEEK CoCr PEEK CoCr PEEK

Clasp connector

3,5 mm² 5,3 mm² 3,0 mm² 4,5 mm² 1,5 mm² 2,3 mm²

Clasp shoulder

1,6 mm² 2,4 mm² 1,8 mm² 2,7 mm² 1,2 mm² 1,8 mm²

Clasp trip

1,2 mm² 1,8 mm² 1,2 mm² 1,8 mm² 1,0 mm² 1,5 mm²

Double rests

2,5 mm² 3,8 mm² - - 1,4 mm² 2,1 mm²

Single rests

- - - - 0,6 mm² 0,9 mm²

Clasp profile thickness

- - - - 0,9 mm² 1,4 mm²

Clasp profile height

- - - - 1,8 mm² 2,7 mm²




It is also important to know that a PEEK partial framework (RPD) cannot be expanded. So if you and the patient have decided on a metal-free alternative, teeth that will have to be replaced in the near future should be taken into account at the planning stage. So push the production of the removable dentures (as far as possible) a little in the future.

Tip 2: Use frameworks that have been milled from PEEK blanks

CAD / CAM bridges made from industrially pre-pressed PEEK blanks are more stable than frameworks made from granulate. The reason for this is that the traditional press technique may result in porosities caused by production. In the CAD/CAM-process, the material does not suffer because it is not subjected to any physical changes. However, it is not only the higher stability that plays a role in the choice of the manufacturing process for frameworks made of PEEK, but also the consistent quality which you can rely on with restorations made of milled PEEK.

Tip 3: Mill PEEK yourself in your laboratory

The high-performance plastics can be milled dry or wet. Sharp, single-edged milling burs are recommended for this. Mill PEEK with low pressure and medium speed. As usual with thermoplastics, even short-term excesses of the melting point can lead to changes in the material properties, so you should definitely avoid this.

Tip 4: Post processing

Using cutting wheels can damage the material, so work with cross-cut burs first. Then use reinforced rubber polishers for pre-polishing. For the subsequent high-gloss polishing, you can use commercially available polishing pastes to achieve a particularly smooth surface and thus reduce the tendency to discolour and plaque build-up.

Tip 5: Only veneer the visible front

In order to be able to guarantee the highest possible stability of the denture, it is better to only veneer the visible front of frameworks made of PEEK plastics. The combination with other materials is not always easy due to the material properties. In order to achieve a higher bond strength, you should first roughen the surface that you want to veneer by blasting it and then use a bonding system approved for PEEK. As usual, use a covering system for veneering that is similar to the physical parameters of PEEK to prevent chipping. No special materials are required for this, veneer your work as usual.

CONCLUSION

PEEK is a special material which, due to its material properties, is not so easy to process. At this point, sufficient experience or instruction and training are necessary in order to achieve a high-quality result. If the high-performance plastics is rarely used, it is worth considering outsourcing design and/or production to a milling service provider. We at CADdent® have been working with PEEK plastics for many years and are happy to support you with advice, training or the milling service itself.