In the presented case, the teeth, which have suffered significant occlusal abrasion or erosion, are to be restored. Before fabricating the definitive restoration, the lost vertical dimension of occlusion must be reconstructed and the occlusal situation stabilized for at least 8 to 12 months. First, the patient's occlusion is functionally repositioned, usually in centric relation. To stabilize the vertical dimension in the mouth, CAD/CAM-fabricated temporary restorations made of PMMA are used. Several material-related details must be considered regarding the cementation of PMMA restorations in the mouth ( see article ). In this case, adhesive cementation is used. Surface preparation and conditioning are 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 "Cementation of PMMA restorations" can be found here: Link