step by step: Fixation of PMMA restorations

In the case presented, the teeth that have been severely abraded or eroded in the occlusal area are to be restored. Before the final restoration can be made, the lost bite height must be reconstructed and the occlusal situation must be stabilized for at least 8 to 12 months. First, the patient is functionally readjusted, usually in a centric condylar position. CAD/CAM-supported temporary restorations made of PMMA are used to stabilize the vertical dimension in the mouth. When it comes to fixing PMMA restorations in the mouth, there are a few material science details that need to be taken into account (see article). In this case, adhesive integration takes place. Surface pretreatment and conditioning is crucial here. A step-by-step example is shown below.

Left: The CAD/CAM-supported PMMA restorations are fitted onto the model. The middle picture shows a close-up view of the model to what extent the hard tooth substance has been abraded/eroded in the occlusal area. The picture on the right shows two of the PMMA restorations used to reconstruct the occlusal dimension.

The inner surfaces of the crowns were marked with a pencil (reason: optimal control for complete blasting with aluminum oxide particles) and then corundum blasted with aluminum oxide particles (50µm) and a pressure of 0,5 bar.

The markings have been completely removed. The adhesive surface is only blown off with oil-free air. SAVE: Do not clean with water after corundum blasting! A silane was applied (here Monobond Plus, Ivoclar Vivadent). Note: Leave on for 1 minute, then blow off. This was followed by the application of a bonder (here Heliobond, Ivoclar Vivadent), without subsequent polymerization. The restorations should then be sufficiently blown off again with oil-free air so that a thin bonding film remains.

The luting composite (here Variolink Esthetic, Ivoclar Vivadent) is applied and evenly distributed on the inner surface of the crown. Note: Cure on all three sides for 20 seconds using an LED curing lamp.

In the picture on the left, two of the PMMA restorations are already bonded. The right image shows all integrated posterior restorations in the quadrant. (Images: Prof. Dr. Daniel Edelhoff)

Authors: Annett Kieschnick, Bogna Stawarczyk, Anja Liebermann

Further information on the topic of “fixing PMMA restorations” here: Link

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Monday, 20 of November 2024
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