” DOUBLE STEP REVERSE”( DSR): A NEW PROTOCOL IN POLYVINYLSILOXANES( PVS) IMPRESSION- TAKING PROCESS- TWO CASE REPORTS
Figure 15. Dental dam application
Figure 16. Etching gel on the dentin
Figure 17. Adhesive application
material has showed a“ Shore hardness” of 63 and, once it is set, it does not tear off when it is time to remove the tray from the mouth.
2.2 Case Report n ° 2 To better highlight the advantages of this technique, we will describe another clinical case where a PVS impression with an Aquasil Ultimate system is carried out within the prosthetic rehabilitation of teeth # 16 and # 17( with juxta-gingival finish line). Case Description A patient with a severe wear of superior posterior teeth comes to our observation, showing tooth # 17 with a massive restoration made of composite resin and # 16 with a complete fracture of the disto-buccal cusp, so they are both in need of prosthetic treatments( Fig. 8). We decided, by mutual agreement with our patient, to treat the two elements by milling a corestructure from a block of IPS e. max ZirCAD( Ivoclar). The CAD-CAM produced COR was veneered with e-max veneering ceramic. Having stated the height of the residual preparation, which guaranteed enough stability and retention of the restoration itself, a juxta-gingival abutment finish line was chosen in order to better control: the marginal
Figure 18. Sandblasting of the inner surface of the ceramic crown
trimming, the impression, the visual check of the finishing edge, the cementation and the full removal of the excess cement. We prepared the two dental elements with a juxtagingival finish line then we placed a retraction cord into the sulcus to highlight the end of the preparations( Fig. 9). As for the temporary crowns, we adapted two provisional resin crowns performed in the laboratory through a direct rebasing.( Fig. 10). We placed a retraction cord( Ultrapack # 00, Ultradent) into the sulcus and, without removing the cord itself, Aquasil Ultimate Wash is delivered into the sulcus and on the preparations, letting it set for 3 minutes, as suggested by the manufacturer( Fig. 11). This short time having elapsed, the tray, filled with Aquasil Ultimate Tray, was slowly seated on the upper arch so that the rest of the impression could be taken. In this stage, we opted for a stiff and smooth steel tray with retentive ridges where the PVS adhesive was already applied. After 3 minutes of setting, as indicated by the manufacturer, the tray was removed from mouth( Fig. 12), then controlled under microscope( Leica M400 optical) at 40x of magnifica-
190 STOMA. EDUJ( 2016) 3( 2)