PMMA temporaries
- manufacture and technical data

When is a provisional solution necessary?

A PMMA resin temporary is necessary for every larger restoration after the preparation. On the one hand to protect the dentin wound against thermal, chemical and bacterial stimuli, on the other hand to guarantee the chewing and speech functions. In the visible area, however, it is not only the function that counts for patients, but also the aesthetics of a temporary, especially when the restoration takes a long time and a long-term temporary is necessary.

There are three possible methods for the manufacturing of temporary restorations

1. Direct temporary

The patient receives a temporary in the dental practice (within approx. 30 minutes). This is why one speaks here of a direct temporary arrangement.

The old oral situation is taken and the temporary is made directly in the patient's mouth using self-curing cold-curing polymer (two-component plastic). The dentist or an assistant usually takes care of the creation of the temporary.

PMMA temporary in CAD/CAM process

A PMMA temporary made in such a short time can often have the wrong bite setting, lead to gingivitis, be unsightly or bothersome. Time and again, patients with direct temporary restorations react sensitively to cold and sweet things. For these reasons, PMMA direct temporaries are mainly used as quick solutions for short-term restorations

2. Eggshell temporary

Eggshell temporaries require considerably more time to manufacture. They are manufactured in the dental laboratory using conventional technology. Since a PMMA temporary created in the dental laboratory is much more precisely fitting, more homogeneous and more aesthetic, this type of production is used in particular for long-term temporary restorations - which remain in the mouth for more than 3 months - e.g. during the healing phase of surgical or implantological restorations. 

In addition to their functional tasks, they also meet the patient's aesthetic requirements and can also serve as a working basis for subsequent care.
 

3. CAD/CAM PMMA temporaries

With the help of the latest technology, temporary restorations can also be manufactured using the CAD/CAM-process. This can either take place in the dental laboratory, if a CAD/CAM-system is available, or it can be outsourced by the dental laboratory to a milling service provider such as CADdent®

As with eggshell temporaries, PMMA is used for long-term temporaries in CAD / CAM temporaries. In contrast to conventional technology, other plastics - such as composites - are also conceivable here. The difference in the manufacturing process lies on the one hand in the digitization of the work steps in the laboratory and on the other in the manufacture of the PMMA. While the latter is done manually in the laboratory for the temporary eggshell, the milling blanks for the CAD/CAM-process are manufactured industrially. Due to the industrial production of the blanks, errors in the polymerization are excluded. In contrast to the direct or eggshell temporary, PMMA is therefore allergy-free.
 

Allgemeine technische Details von PMMA

In a study  by the University of Zurich, the breaking load of various temporary plastics was tested.

With CAD / CAM materials, it could be demonstrated a higher breaking load for PMMA (such as  VITA CAD-Temp®) in contrast to composite. The direct temporary restoration showed the lowest breaking load in the test.
 

The minimum requirements and the necessary tests for PMMA are regulated in DIN EN ISO 1567. A value of 80 * 10-6 is specified for the coefficient of thermal expansion (CTE). 

The melting point of PMMA resins is approximately between 130 and 140°C.

PMMA plastics are only soluble in a few solvents such as acetone.

PMMA materials in CADdent® portfolio

At CADdent® we process various PMMA milling blanks.

For PMMA temporaries we offer the Idodentine Monocolor PMMA in the shades A1, A2, A3, A3,5, B2, C2, D2.

This PMMA temporary resin is suitable for the following indications:
•    Temporary restorations up to 12 months
•    Crown and bridges  up to 16 units with a maximum of two pontics
•    Splints
 

Technical details

Density

1,18 g / cm  

     
Flexural strength 

90 MPa

     

Water absorption   

23 μg / mm      

Modulus of elasticity    

2300 MPa      


For splints, we also offer CADdent® PMMA in the colors pink, blue, orange and green.